One document matched: draft-ietf-nsis-qspec-12.txt
Differences from draft-ietf-nsis-qspec-11.txt
IETF Internet Draft NSIS Working Group Jerry Ash
Internet Draft AT&T
<draft-ietf-nsis-qspec-12.txt> Attila Bader
Expiration Date: April 2007 Ericsson
Cornelia Kappler
Siemens AG
October 2006
QoS NSLP QSPEC Template
Status of this Memo
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This Internet-Draft will expire on April 4, 2007.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
The QoS NSLP protocol is used to signal QoS reservations and is
independent of a specific QoS model (QOSM) such as IntServ or
DiffServ. Rather, all information specific to a QOSM is encapsulated
in a separate object, the QSPEC. This document defines a template
for the QSPEC, which contains both the QoS description and QSPEC
control information. The QSPEC format is defined, as are a number of
QSPEC parameters. The QSPEC-1 parameters provide a common language
to be re-used in several QOSMs. QSPEC-2 parameters aim to ensure
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the extensibility of QoS NSLP to other QOSMs in the future. To a
certain extent QSPEC parameters ensure interoperability of QOSMs.
The node initiating the NSIS signaling adds an Initiator QSPEC that
must not be removed, thereby ensuring the intention of the NSIS
initiator is preserved along the signaling path.
Table of Contents
1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. QOSM/NSLP Framework . . . . . . . . . . . . . . . . . . . . . . 7
5. QSPEC Framework . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1 QSPEC Objects . . . . . . . . . . . . . . . . . . . . . . . 10
5.2 QSPEC Parameters . . . . . . . . . . . . . . . . . . . . . 11
5.2.1 QSPEC-1 and QSPEC-2 Parameters . . . . . . . . . . . 11
5.2.2 Read-only and Read-write QSPEC Parameters . . . . . . 11
5.3 QSPEC Formats . . . . . . . . . . . . . . . . . . . . . . . 12
5.3.1 QSPEC Control Information . . . . . . . . . . . . . . 13
5.3.2 QoS Description . . . . . . . . . . . . . . . . . . . 13
5.3.2.1 <QoS Desired> . . . . . . . . . . . . . . . . 13
5.3.2.2 <QoS Available> . . . . . . . . . . . . . . . 15
5.3.2.3 <QoS Reserved> . . . . . . . . . . . . . . . 17
5.3.2.4 <Minimum QoS> . . . . . . . . . . . . . . . . 17
6. QSPEC Processing & Procedures . . . . . . . . . . . . . . . . . 18
6.1 Interpreting QSPEC Parameters . . . . . . . . . . . . . . . 18
6.2 QSPEC Stacking & Tunneling . . . . . . . . . . . . . . . . 19
6.3 Reservation Success/Failure, QSPEC Error Codes, & INFO_SPEC
Notification . . . . . . . . . . . . . . . . . . . . . . . 21
6.3.1 Reservation Failure & Error E-Flag . . . . . . . . . 22
6.3.2 Non-QOSM-Hop Q-Flag & Remapped QSPEC Parameter
R-flag . . . . . . . . . . . . . . . . . . . . . . . 22
6.3.3 QSPEC Parameter Not Supported N-Flag . . . . . . . . 23
6.3.4 INFO_SPEC Coding of Reservation Outcome . . . . . . . 23
6.3.5 QNE Generation of a RESPONSE message . . . . . . . . 24
6.3.6 Domains Supporting a Different Local QOSM than the
QNI . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.3.7 Special Cases of QSPEC Stacking . . . . . . . . . . . 26
6.4 QSPEC Procedures . . . . . . . . . . . . . . . . . . . . . 26
6.4.1 Sender-Initiated Reservations . . . . . . . . . . . . 26
6.4.2 Receiver-Initiated Reservations . . . . . . . . . . . 28
6.4.3 Resource Queries . . . . . . . . . . . . . . . . . . 30
6.4.4 Bidirectional Reservations . . . . . . . . . . . . . 30
6.4.5 Preemption . . . . . . . . . . . . . . . . . . . . . 30
6.5 QSPEC Extensibility . . . . . . . . . . . . . . . . . . . . 30
7. QSPEC Functional Specification . . . . . . . . . . . . . . . . 31
7.1 General QSPEC Formats . . . . . . . . . . . . . . . . . . . 32
7.2 QSPEC-1 Parameter Coding . . . . . . . . . . . . . . . . . 35
7.2.1 <Excess Treatment> Parameter . . . . . . . . . . . . 35
7.2.2 <Traffic> Parameter . . . . . . . . . . . . . . . . . 36
7.2.2.1 <Bandwidth> Sub-Parameter . . . . . . . . . . 37
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7.2.2.2 <Token Bucket-1> Sub-Parameters . . . . . . . 37
7.2.3 <QoS Class> Parameter . . . . . . . . . . . . . . . . 38
7.2.3.1 <PHB Class> Sub-Parameter . . . . . . . . . . 38
7.2.3.2 <DSTE Class Type> Sub-Parameter . . . . . . . 39
7.2.3.3 <Y.1541 QoS Class> Sub-Parameter . . . . . . 39
7.2.4 <Priority> Parameter . . . . . . . . . . . . . . . . 40
7.2.4.1 <Preemption Priority> & <Defending Priority>
Sub-Parameters . . . . . . . . . . . . . . . 42
7.2.4.2 <Admission Priority> Sub-Parameter . . . . . 42
7.2.4.3 <RPH Priority> Sub-Parameter . . . . . . . . 42
7.3 QSPEC-2 Parameter Coding . . . . . . . . . . . . . . . . . 43
7.3.1 <Token Bucket-2> Parameter . . . . . . . . . . . . . 43
7.3.2 <Path Latency> Parameter . . . . . . . . . . . . . . 44
7.3.3 <Path Jitter> Parameter . . . . . . . . . . . . . . . 44
7.3.4 <Path PLR> Parameter . . . . . . . . . . . . . . . . 45
7.3.5 <Path PER> Parameter . . . . . . . . . . . . . . . . . . . 46
7.3.6 <Ctot> <Dtot> <Csum> <Dsum> Parameters . . . . . . . 46
7.3.7 <Slack Term> Parameter . . . . . . . . . . . . . . . 47
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 48
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 48
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 52
11. Normative References . . . . . . . . . . . . . . . . . . . . . 52
12. Informative References . . . . . . . . . . . . . . . . . . . . 53
13. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 54
Appendix A. Example of QSPEC Processing . . . . . . . . . . . . . 55
Appendix B. Mapping of QoS Desired, QoS Available and QoS
Reserved of NSIS onto AdSpec, TSpec and RSpec of RSVP
IntServ . . . . . . . . . . . . . . . . . . . . . . . 59
Appendix C. Change History & Open Issues . . . . . . . . . . . . . 59
C.1 Change History (since Version -04) . . . . . . . . 59
C.2 Open Issues . . . . . . . . . . . . . . . . . . . 61
Intellectual Property Statement . . . . . . . . . . . . . . . . . 61
Disclaimer of Validity . . . . . . . . . . . . . . . . . . . . . . 62
Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1. Contributors
This document is the result of the NSIS Working Group effort. In
addition to the authors/editors listed in Section 13, the following
people contributed to the document:
Chuck Dvorak
AT&T
Room 2A37
180 Park Avenue, Building 2
Florham Park, NJ 07932
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Phone: + 1 973-236-6700
Fax:+1 973-236-7453
Email: cdvorak@att.com
Yacine El Mghazli
Alcatel
Route de Nozay
91460 Marcoussis cedex
FRANCE
Phone: +33 1 69 63 41 87
Email: yacine.el_mghazli@alcatel.fr
Georgios Karagiannis
University of Twente
P.O. BOX 217
7500 AE Enschede
The Netherlands
Email: g.karagiannis@ewi.utwente.nl
Andrew McDonald
Siemens/Roke Manor Research
Roke Manor Research Ltd.
Romsey, Hants SO51 0ZN
UK
Email: andrew.mcdonald@roke.co.uk
Al Morton
AT&T
Room D3-3C06
200 S. Laurel Avenue
Middletown, NJ 07748
Phone: + 1 732 420-1571
Fax: +.1 732 368-1192
Email: acmorton@att.com
Percy Tarapore
AT&T
Room D1-33
200 S. Laurel Avenue
Middletown, NJ 07748
Phone: + 1 732 420-4172
Email: tarapore@.att.com
Lars Westberg
Ericsson Research
Torshamnsgatan 23
SE-164 80 Stockholm, Sweden
Email: Lars.Westberg@ericsson.com
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2. Introduction
The QoS NSIS signaling layer protocol (NSLP) [QoS-SIG] establishes
and maintains state at nodes along the path of a data flow for the
purpose of providing forwarding resources (QoS) for that flow. The
design of QoS NSLP is conceptually similar to RSVP [RFC2205], and
meets the requirements of [RFC3726].
A QoS-enabled domain supports a particular QoS model (QOSM), which is
a method to achieve QoS for a traffic flow. A QOSM incorporates QoS
provisioning methods and a QoS architecture. It defines the behavior
of the resource management function (RMF) defined in [QoS-SIG],
including inputs and outputs. Examples of QOSMs are IntServ, DiffServ
admission control, and those specified in [Y.1541-QOSM, CL-QOSM,
RMD-QOSM].
The QoS NSLP protocol is used to signal QoS reservations and supports
signaling for different QOSMs. All information specific to a QOSM is
encapsulated in the QoS specification (QSPEC) object, which is QOSM
specific, and this document defines a template for the QSPEC.
Since QoS NSLP signaling operation can be different for different
QOSMs, the QSPEC contains two kinds of information, QSPEC control
information and QoS description. QSPEC control information contains
parameters that governs the behavior of the RMF. An example of QSPEC
control information is how the excess traffic is treated in the RMF
queuing functions. The QoS description parameters include, for
example, <Traffic> parameters, such as <Token Bucket> and
<Bandwidth>, and constraints parameters, such as <PHB Class> and
<Path Latency>.
The QoS description is composed of QSPEC objects loosely
corresponding to the TSpec, RSpec and AdSpec objects specified in
RSVP. This is, the QSPEC may contain a description of QoS desired
and QoS reserved. It can also collect information about available
resources. Going beyond RSVP functionality, the QoS description
also allows indicating a range of acceptable QoS by defining a QSPEC
object denoting minimum QoS. Usage of these QSPEC objects is not
bound to particular message types thus allowing for flexibility.
A QSPEC object collecting information about available resources may
travel in any QoS NSLP message, for example a QUERY message or a
RESERVE message. The QSPEC travels in QoS NSLP messages but is
opaque to the QoS NSLP, and is only interpreted by the RMF.
Interoperability between QoS NSIS entities (QNEs) in different
domains that implement different QOSMs is enhanced (but not
guaranteed) by the definition of a common set of QSPEC-1 and
QSPEC-2 parameters. QSPEC-1 parameters in the QSPEC must be
interpreted by all QNEs in the path, independent of which QOSM they
support. This way, NSIS provides a mechanism for interdomain QoS
signaling and interworking. QSPEC-2 parameters, in contrast, may be
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skipped if not understood. Additional QSPEC-2 parameters can be
defined by QOSM specification documents, and thereby ensure the
extensibility and flexibility of QoS NSLP.
A QoS NSIS initiator (QNI) initiating the QoS NSLP signaling adds an
initiator QSPEC object containing parameters describing the desired
QoS based on the QOSM it supports. A local QSPEC can be stacked on
the initiator QSPEC to accommodate different QOSMs being used in
different domains. A domain supporting a different local QOSM than
the QNI can interpret the initiator QSPEC and stack a local QSPEC
to meet the local QOSM requirements. If the local domain cannot
fully interpret the initiator QSPEC, it can flag the condition and
either continue to forward the reservation or possibly reject the
reservation.
Thus, one of the major differences between RSVP and QoS NSLP is that
QoS NSLP supports signaling for different QOSMs along the data path,
all with one signaling message. For example, the data path may start
in a domain supporting DiffServ and end in a domain supporting
Y.1541. The ability to achieve end-to-end QoS through multiple
Internet domains is also an important requirement, and illustrated
in this document.
3. Terminology
Minimum QoS: Minimum QoS is a QSPEC object that MAY be supported by
any QNE. Together with a description of QoS Desired or QoS
Available, it allows the QNI to specify a QoS range, i.e. an upper
and lower bound. If the QoS Desired cannot be reserved, QNEs are
going to decrease the reservation until the minimum QoS is hit.
QNE: QoS NSIS Entity, a node supporting QoS NSLP.
QNI: QoS NSIS Initiator, a node initiating QoS NSLP signaling.
QNR: QoS NSIS Receiver, a node terminating QoS NSLP signaling.
QoS Description: Describes the actual QoS in QSPEC objects QoS
Desired, QoS Available, QoS Reserved, and Minimum QoS. These QSPEC
objects are input or output parameters of the RMF. In a valid QSPEC,
at least one QSPEC object of the type QoS Desired, QoS Available or
QoS Reserved MUST be included.
QoS Available: QSPEC object containing parameters describing the
available resources. They are used to collect information along a
reservation path.
QoS Desired: QSPEC object containing parameters describing the
desired QoS for which the sender requests reservation.
QoS Model (QOSM): A method to achieve QoS for a traffic flow, e.g.,
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IntServ Controlled Load. A QOSM specifies a set of QSPEC-1 and
QSPEC-2 parameters that describe the QoS and how resources
will be managed by the RMF. It furthermore specifies how to use QoS
NSLP to signal for this QOSM.
QoS Reserved: QSPEC object containing parameters describing the
reserved resources and related QoS parameters, for example,
bandwidth.
QSPEC Control Information: Control information that is specific to a
QSPEC, and contains parameters that govern the RMF.
QSPEC: QSPEC is the object of QoS NSLP containing all QOSM-specific
information.
QSPEC parameter: Any parameter appearing in a QSPEC; includes both
QoS description and QSPEC control information parameters, for
example, bandwidth, token bucket, and excess treatment parameters.
QSPEC Object: Main building blocks of QoS Description containing a
QSPEC parameter set that is input or output of an RMF operation.
QSPEC-1 parameter: QSPEC parameter that a QNI SHOULD populate if
applicable to the QOSM supported by the QNI and a QNE MUST interpret,
if populated.
QSPEC-2 parameter: QSPEC parameter that a QNI SHOULD populate if
applicable to the QOSM supported by the QNI, and a QNE SHOULD
interpret if populated and applicable to the QOSM(s) supported by the
QNE. (A QNE MAY ignore if it does not support a QOSM needing the
QSPEC-2 parameter).
Resource Management Function (RMF): Functions that are related to
resource management, specific to a QOSM. It processes the QoS
description parameters and QSPEC control parameters.
Read-only Parameter: QSPEC Parameter that is set by initiating or
responding QNE and is not changed during the processing of the QSPEC
along the path.
Read-write Parameter: QSPEC Parameter that can be changed during the
processing of the QSPEC by any QNE along the path.
4. QOSM/NSLP Framework
The overall framework for the QoS NSLP is that [QoS-SIG] defines QoS
signaling and semantics, the QSPEC template defines the container and
semantics for QoS parameters and objects, and QOSM specifications
define QoS methods and procedures for using QoS signaling and QSPEC
parameters/objects within specific QoS deployments. QoS NSLP is a
generic QoS signaling protocol that can signal for many QOSMs.
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A QOSM is a method to achieve QoS for a traffic flow, e.g., IntServ
controlled load [CL-QOSM], resource management with DiffServ
[RMD-QOSM], and QoS signaling for Y.1541 QoS classes [Y.1541-QOSM].
A QOSM specifies a set of QSPEC parameters that describe the QoS
desired and how resources will be managed by the RMF. It furthermore
specifies how to use QoS NSLP to signal for this QOSM. The QSPEC is
the object of QoS NSLP containing all QOSM-specific information,
which is described in the next section, such as QoS description
parameters (e.g., bandwidth) and QSPEC control information parameters
(e.g., excess treatment). The RMF implements functions that are
related to resource management, specific to a QOSM and processes the
QSPEC parameters.
The QOSM specification includes how the requested QoS resources will
be described and how they will be managed by the RMF. For this
purpose, the QOSM specification defines a set of QSPEC-1 and QSPEC-2
parameters it uses to describe the desired QoS and QoS resource
control in the RMF, and it may define additional QSPEC-2 parameters.
QSPEC-1 parameters are populated by a QNI if they are applicable to
the underlying QOSM the QNI supports and that a QNE must interpret,
if populated. QSPEC-2 parameters are populated by a QNI if they are
applicable to the underlying QOSM a QNI supports, and a QNE should
interpret if populated and applicable to the QOSM(s) supported by the
QNE.
A QNE MUST support at least one QOSM. A QoS-enabled domain supports
a particular QOSM, and the QNEs in the domain MUST also support the
QOSM.
A QOSM specification MUST include the following:
- role of QNEs, e.g., location, frequency, statefulness, etc.
- QSPEC definition including QOSM ID, QSPEC parameters
- QSPEC procedures applicable to this QOSM
- QNE processing rules describing how QSPEC information is treated
and interpreted in the RMF and QOSM specific processing. E.g.,
admission control, scheduling, policy control, QoS parameter
accumulation (e.g., delay).
- at least one bit-level QSPEC example
- QSPEC parameter behavior for new QSPEC-2 parameters the QOSM
specification defines
- QSPEC parameter behavior for remapping of existing QSPEC
parameters, as described in Section 6.3.2. Remapping may result
in slight modification to the intended specification when strict
interpretation is not possible. Unless otherwise specified in the
QOSM specification document, the default QOSM behaviors for all
QSPEC-1 parameters is to strictly interpret the QSPEC-1 parameters
as defined in this document through the references that precisely
define the QSPEC parameter behaviors.
- define what happens in case of preemption if the default QNI
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behavior (tear down preempted reservation) is not followed (see
Section 6.3.5)
A QOSM specification MAY include the following:
- QOSM-specific control information parameters and processing rules
for those parameters
- define additional QOSM-specific error codes, as discussed in
Section 6.3.4
- specify the conditions for rejecting a reservation when the
non-QOSM-hop Q-flag and remapped QSPEC parameter R-flags are sent
back in the RESPONSE message (in the absence of such procedures,
the default condition is 'success' if all QSPEC parameters are met
and 'reservation failure' if one or more QSPEC parameters are not
met)
5. QSPEC Framework
The QSPEC is the object of QoS NSLP containing all QOSM-specific
information, and contains QSPEC objects and parameters. QSPEC
objects are the main building blocks of the QoS description
containing a QSPEC parameter set that is input or output of an RMF
operation. QSPEC parameters are the parameters appearing in a QSPEC,
which include both QoS description parameters (e.g., bandwidth) and
QSPEC control information parameters (e.g., excess treatment). The
RMF implements functions that are related to resource management,
specific to a QOSM. It processes the QoS description parameters and
QSPEC control information parameters.
QSPEC-1 parameters provide a common language for QOSM developers to
build their QSPECs and are likely to be re-used in several QOSMs.
QSPEC-1 parameters are populated by a QNI if they are applicable to
the underlying QOSM the QNI supports and that a QNE must interpret,
if populated. QSPEC-2 parameters are populated by a QNI if they are
applicable to the underlying QOSM a QNI supports, and a QNE should
interpret if populated and applicable to the QOSM(s) supported by the
QNE. Note that a QNE may ignore a QSPEC-2 parameter if it does not
support a QOSM needing the QSPEC-2 parameter. QSPEC-1 and QSPEC-2
parameters are defined in this document, and additional QSPEC-2
parameters may be defined in separate QOSM specification documents.
For example, QSPEC-2 parameters are defined in [RMD-QOSM] and
[Y.1541-QOSM]. The set of QSPEC-1 parameters in NSIS is based on
DiffServ and IntServ/RSVP. Note that in effect all parameters are
QSPEC-1 in RSVP since it does not have the QSPEC-1/QSPEC-2 concept.
In this document the term 'interpret' means, in relation to RMF
processing of QSPEC parameters, either that the RMF a) strictly
interprets a QSPEC parameter, or b) remaps, approximates, or
otherwise does not strictly interpret the parameter. Furthermore,
the terminology 'strictly interpret' means that the QSPEC parameter
is processed by the RMF according to the commonly accepted normative
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procedures specified by references given for each QSPEC parameter.
Otherwise the QSPEC parameter may be remapped or approximately
interpreted. For example a token bucket parameter may be remapped to
bandwidth and simply interpreted by the RMF as bandwidth. Note also
that a QNE must interpret a QSPEC-1 parameter only if it is populated
in the QSPEC object by the QNI. If a QSPEC-1 parameter is not there
in the QSPEC, the QNE does not interpret it of course. To test
compliance, however, a QNE would need to be tested that it properly
implements/interprets all QSPEC-1 parameters.
5.1 QSPEC Objects
This document provides a template for the QSPEC, which is needed in
order to help define individual QOSMs and in order to promote
interoperability between QOSMs. Figure 1 illustrates how the QSPEC
is composed of QSPEC control information and QoS description. QoS
description in turn is composed of up to four QSPEC objects (not all
of them need to be present), namely QoS Desired, QoS Available, QoS
Reserved and Minimum QoS. Each of these QSPEC Objects, as well as
QSPEC Control Information, consists of a number of QSPEC-1 and
QSPEC-2 parameters.
+-------------+---------------------------------------+
|QSPEC Control| QoS |
| Information | Description |
+-------------+---------------------------------------+
\________________ ______________________/
V
+----------+----------+---------+-------+ \
|QoS Desir.|QoS Avail.|QoS Rsrv.|Min QoS| > QSPEC
+----------+----------+---------+-------+ / Objects
\_______ ____/\____ ____/\___ _____/\___ ____/\__ ___/
V V V V V
+-------------+... +-------------+...
|QSPEC Para. 1| |QSPEC Para. n|
+-------------+... +-------------+...
Figure 1: Structure of the QSPEC
The internal structure of each QSPEC object and the QSPEC control
information, with QSPEC-1 and QSPEC-2 parameters, is illustrated
in Figure 2.
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+------------------+-----------------+------------------+
| QSPEC/Ctrl Info | QSPEC-1 | QSPEC-2 |
| Object ID | Parameters | Parameters |
+------------------+-----------------+------------------+
Figure 2: Structure of QSPEC Objects & Control Information
5.2 QSPEC Parameters
5.2.1 QSPEC-1 and QSPEC-2 Parameters
QSPEC-1 and QSPEC-2 parameters are defined in this document and are
applicable to a number of QOSMs. QSPEC-1 parameters are treated as
follows:
o A QNI SHOULD populate QSPEC-1 parameters if applicable to the
QOSM supported by the QNI.
o QNEs/QNR MUST interpret QSPEC-1 parameters, if signaled.
QSPEC-2 parameters are treated as follows:
o A QNI SHOULD populate QSPEC-2 parameters if applicable to the QOSM
for which it is signaling.
o QNEs/QNR SHOULD interpret QSPEC-2 parameters, if signaled and
applicable to the QOSM(s) supported by the QNE/QNR. (A QNE/QNR MAY
ignore the QSPEC-2 parameter if it does not support a QOSM needing
the QSPEC-2 parameter).
Note that a QNE that stacks 2 QSPECs should follow the same rules as
a QNI. That is, when there are two stacked QSPECs in a local domain,
the QNEs in the interior local domain need only process the local
(topmost) QSPEC and can ignore the initiator (bottom) QSPEC.
However, edge QNEs in the local domain indeed must interpret the
QSPEC-1 parameters populated in the initiator QSPEC.
This specification defines 4 QSPEC-1 parameters: <Excess Treatment>,
<Traffic>, <QoS Class>, and <Priority>. The coding for these
parameters is specified in Section 7.2. Due to a lack of sufficient
deployment experience this is a best guess, which should be reviewed
once operational experience requires or allows such a review. This
specification also defines 10 QSPEC-2 parameters, and the coding for
these parameters is specified in Section 7.3.
5.2.2 Read-only and Read-write QSPEC Parameters
QoS description parameters can be either read-only or read-write,
depending on which QSPEC object, and which message, they appear in.
In particular, all parameters in the QoS Desired object, QoS Reserved
object, and Minimum QoS object are read-only for all messages.
Parameters in the QoS Available object are normally read-write
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parameters when the QoS Available object appears for the first time
e.g. in the RESERVE message or QUERY message from QNI to QNR.
However, on its way back, all parameters in the <QoS Available>
object are read-only, e.g., in the RESPONSE message or RESERVE
message from QNR to QNI. This is because on its way back the QoS
Available object just transports the information it collected before.
In the QSPEC control information object, the property of being
read-write or read-only is parameter specific. Note that the only
control information parameter specified in this document is the
<excess treatment> parameter, which is a read-only parameter.
5.3 QSPEC Formats
QSPEC = <QSPEC Version> <QOSM ID> <QSPEC Control Information>
<QoS Description>
As described above, the QSPEC contains an identifier for the QOSM,
the actual resource description (QoS description) as well as QSPEC
control information. QSPEC-1 parameters defined in the following
sections include <Excess Treatment>, <Traffic>, <QoS Class>, and
<Priority>. All other QSPEC parameters defined in the following
sections are QSPEC-2 parameters.
A QSPEC object ID identifies whether the object is <QSPEC Control
Information> or <QoS Description>. As described below, the <QoS
Description> is further broken down into <QoS Desired>, <QoS
Available>, <QoS Reserved>, and <Minimum QoS> objects. A QSPEC
parameter ID is assigned to identify each QSPEC parameter defined
below.
<QSPEC Version> identifies the QSPEC version number. Later QSPEC
versions MUST be backward compatible with earlier QSPEC versions.
That is, a version n+1 device must support a version n (or earlier)
QSPEC and QSPEC parameters. If the version n device receives
QSPEC-1 parameters (with the M-flag set, as defined in Section 7)
that are not supported in version n (only supported in version
n+1), then the version n device concludes that either a) the M-flag
is set incorrectly for an QSPEC-2 parameter it does not support, or
b) the M-flag is correctly set for a QSPEC-1 parameter it does not
support. In either case, the version n device responds with a
'Malformed QSPEC' error code (0x03), as discussed in Section 6.3.1.
A new QSPEC version MUST be defined whenever this document is
reissued, for example, whenever a new QSPEC-1 parameter is added.
QSPEC-1 parameters in a new QSPEC version MUST be a superset of
those in the previous QSPEC version.
The <QOSM ID> identifies the particular QOSM being used by the QNI
and tells a QNE which parameters to expect. This may simplify
processing and error analysis. Furthermore, it may be helpful for a
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QNE or a domain supporting more than one QOSM to learn which QOSM the
QNI would like to have in order to use the most suitable QOSM. Even
if a QNE does not support the QOSM it MUST interpret at least the
QSPEC-1 parameters. Note that more parameters than required by the
QOSM can be included by the QNI. QSPEC version and QOSM IDs are
assigned by IANA.
5.3.1 QSPEC Control Information
QSPEC control information is used for signaling QOSM RMF functions
not defined in QoS NSLP. It enables building new RMF functions
required by a QOSM within a QoS NSLP signaling framework, such as
specified, for example, in [RMD-QOSM] and [Y.1541-QOSM].
<QSPEC Control Information> = <Excess Treatment>
The <Excess Treatment> parameter describes how the QNE will process
excess traffic, that is, out-of-profile traffic. Excess traffic MAY
be dropped, shaped and/or remarked. The excess treatment parameter is
initially set by the QNI and is read-only.
5.3.2 QoS Description
The QoS Description is broken down into the following QSPEC objects:
<QoS Description> = <QoS Desired> <QoS Available> <QoS Reserved>
<Minimum QoS>
Any subset of the QSPEC objects on the right hand side of the equal
sign can be included in the QSPEC. Of these QSPEC objects, QoS
Desired, QoS Available and QoS Reserved MUST be supported by QNEs.
Minimum QoS MAY be supported.
5.3.2.1 <QoS Desired>
<QoS Desired> = <Traffic> <QoS Class> <Priority>
<Path Latency> <Path Jitter> <Path PLR> <Path PER>
Any subset of the QSPEC parameters on the right hand side of the
equal sign can be included in the <QoS desired> object. These
parameters describe the resources the QNI desires to reserve and
hence this is a read-only QSPEC object. The <QoS Desired> resources
that the QNI wishes to reserve are of course directly related to the
traffic the QNI is going to inject into the network. Therefore, when
used in the <QoS Desired> object, <Traffic> refers to traffic
injected by the QNI into the network.
<Traffic> = <Bandwidth> <Token Bucket>
Either sub-parameter on the right hand side of the equal sign can be
included in the <Traffic> parameter. Here
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<Bandwidth> = link bandwidth needed by flow [RFC2212, RFC2215]
<Token Bucket> = <r> <b> <p> <m> <MTU> [RFC2210]
All of the sub-parameters on the right hand side of the equal sign
MUST be included in the <Token Bucket> parameter. Note that the Path
MTU Discovery (PMTUD) working group is currently specifying a robust
method for determining the MTU supported over an end-to-end path.
This new method is expected to update RFC1191 and RFC1981, the
current standards track protocols for this purpose.
<QoS Class> = <PHB Class> <DSTE Class Type> <Y.1541 QoS Class>
Any one of the sub-parameter on the right hand side of the equal sign
can be included in the <QoS Class> parameter.
An application MAY like to reserve resources for packets with a
particular QoS class, e.g. a DiffServ per-hop behavior (PHB)
[RFC2475], DiffServ-aware MPLS traffic engineering (DSTE) class
type [RFC3564, RFC4124], or Y.1541 QoS class [Y.1541].
<Priority> = <Preemption Priority> <Defending Priority>
<Admission Priority> <RPH Priority>
Any subset of the sub-parameter on the right hand side of the equal
sign can be included in the <Priority> parameter.
<Preemption Priority> is the priority of the new flow compared with
the defending priority of previously admitted flows. Once a flow is
admitted, the preemption priority becomes irrelevant. <Defending
Priority> is used to compare with the preemption priority of new
flows. For any specific flow, its preemption priority MUST always be
less than or equal to the defending priority. <Admission Priority>
and <RPH Priority> provide an essential way to differentiate flows
for emergency services, ETS, E911, etc., and assign them a higher
admission priority than normal priority flows and best-effort
priority flows.
Appropriate security measures need to be taken to prevent abuse of
the <Priority> parameters, see Section 8 on Security Considerations.
[Y.1540] defines packet transfer outcomes, as follows:
Successful: packet arrives within the preset waiting time with no
errors
Lost: packet fails to arrive within the waiting time
Errored: packet arrives in time, but has one or more bit errors
in the header or payload
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Packet Loss Ratio (PLR) = total packets lost/total packets sent
Packet Error Ratio (PER) = total errored packets/total packets sent
<Path Latency>, <Path Jitter>, <Path PLR>, and <Path PER> are QSPEC-2
parameters describing the desired path latency, path jitter and path
bit error rate respectively. Since these parameters are cumulative,
an individual QNE cannot decide whether the desired path latency,
etc., is available, and hence they cannot decide whether a
reservation fails. Rather, when these parameters are included in
<Desired QoS>, the QNI SHOULD also include corresponding parameters
in a <QoS Available> QSPEC object in order to facilitate collecting
this information.
5.3.2.2 <QoS Available>
<QoS Available> = <Traffic> <QoS Class> <Priority>
<Path Latency> <Path Jitter> <Path PLR> <Path PER>
<Ctot> <Dtot> <Csum> <Dsum>
Any subset of the QSPEC parameters on the right hand side of the
equal sign can be included in the <QoS Available> object.
When used in the <QoS Available> object, <Traffic> refers to traffic
resources available at a QNE in the network.
The <QoS Available> Object collects information on the resources
currently available on the path when it travels in a RESERVE or QUERY
message and hence in this case this QSPEC object is read-write. Each
QNE MUST inspect all parameters of this QSPEC object, and if
resources available to this QNE are less than what a particular
parameter says currently, the QNE MUST adapt this parameter
accordingly. Hence when the message arrives at the recipient of the
message, <QoS Available> reflects the bottleneck of the resources
currently available on a path. It can be used in a QUERY message,
for example, to collect the available resources along a data path.
When <QoS Available> travels in a RESPONSE message, it in fact just
transports the result of a previous measurement performed by a
RESERVE or QUERY message back to the initiator. Therefore in this
case, <QoS Available> is read-only.
The parameters <Token Bucket> and <Bandwidth> provide information,
for example, about the bandwidth available along the path followed by
a data flow. The local parameter is an estimate of the bandwidth the
QNE has available for packets following the path. Computation of the
value of this parameter SHOULD take into account all information
available to the QNE about the path, taking into consideration
administrative and policy controls on bandwidth, as well as physical
resources. The composition rule for this parameter is the MIN
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function. The composed value is the minimum of the QNE's value and
the previously composed value. This quantity, when composed
end-to-end, informs the QNR (or QNI in a RESPONSE message) of the
minimal bandwidth link along the path from QNI to QNR.
The <Path Latency> parameter accumulates the latency of the packet
forwarding process associated with each QNE, where the latency is
defined to be the mean packet delay added by each QNE. This delay
results from speed-of-light propagation delay, from packet processing
limitations, or both. The mean delay reflects the variable queuing
delay that may be present. Each QNE MUST add the propagation delay
of its outgoing link, if this link exists. Furthermore, the QNI MUST
add the propagation delay of the ingress link, if this link exists.
The composition rule for the <Path Latency> parameter is summation
with a clamp of (2**32 - 1) on the maximum value. This quantity,
when composed end-to-end, informs the QNR (or QNI in a RESPONSE
message) of the minimal packet delay along the path from QNI to QNR.
The purpose of this parameter is to provide a minimum path latency
for use with services which provide estimates or bounds on additional
path delay [RFC2212].
The <Path Jitter> parameter accumulates the jitter of the packet
forwarding process associated with each QNE, where the jitter is
defined to be the nominal jitter added by each QNE. IP packet
jitter, or delay variation, is defined in [RFC3393], Section 3.4
(Type-P-One-way-ipdv), and where the selection function includes the
packet with minimum delay such that the distribution is equivalent to
2-point delay variation in [Y.1540]. The suggested evaluation
interval is 1 minute. This jitter results from packet processing
limitations, and includes any variable queuing delay which may be
present. Each QNE MUST add the jitter of its outgoing link, if this
link exists. Furthermore, the QNI MUST add the jitter of the ingress
link, if this link exists. The composition method for the <Path
Jitter> parameter is the combination of several statistics describing
the delay variation distribution with a clamp on the maximum value
(note that the methods of accumulation and estimation of nominal QNE
jitter are specified in clause 8 of [Y.1541]). This quantity, when
composed end-to-end, informs the QNR (or QNI in a RESPONSE message)
of the nominal packet jitter along the path from QNI to QNR. The
purpose of this parameter is to provide a nominal path jitter for use
with services that provide estimates or bounds on additional path
delay [RFC2212].
The <Path PLR> parameter accumulates the packet loss rate (PLR) of
the packet forwarding process associated with each QNE, where the PLR
is defined to be the PLR added by each QNE. Each QNE MUST add the
PLR of its outgoing link, if this link exists. Furthermore, the QNI
MUST add the PLR of the ingress link, if this link exists. The
composition rule for the <Path PLR> parameter is summation with a
clamp on the maximum value (this assumes sufficiently low PLR values
such that summation error is not significant, however a more accurate
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composition function is specified in clause 8 of [Y.1541]). This
quantity, when composed end-to-end, informs the QNR (or QNI in a
RESPONSE message) of the minimal packet PLR along the path from QNI
to QNR.
The <Path PER> parameter accumulates the packet error rate (PER) of
the packet forwarding process associated with each QNE, where the PER
is defined to be the PER added by each QNE. Each QNE MUST add the
PER of its outgoing link, if this link exists. Furthermore, the QNI
MUST add the PER of the ingress link, if this link exists. The
composition rule for the <Path PER> parameter is summation with a
clamp on the maximum value (this assumes sufficiently low PER values
such that summation error is not significant, however a more accurate
composition function is specified in clause 8 of [Y.1541]). This
quantity, when composed end-to-end, informs the QNR (or QNI in a
RESPONSE message) of the minimal packet PER along the path from QNI
to QNR.
<Ctot>, <Dtot>, <Csum>, <Dsum>: Error terms C and D represent how the
element's implementation of the guaranteed service deviates from the
fluid model. These two parameters have an additive composition rule.
The error term C is the rate-dependent error term. It represents the
delay a datagram in the flow might experience due to the rate
parameters of the flow. The error term D is the rate-independent,
per-element error term and represents the worst case non-rate-based
transit time variation through the service element. If the
composition function is applied along the entire path to compute the
end-to-end sums of C and D (<Ctot> and <Dtot>) and the resulting
values are then provided to the QNR (or QNI in a RESPONSE message).
<Csum> and <Dsum> are the sums of the parameters C and D between the
last reshaping point and the current reshaping point.
5.3.2.3 <QoS Reserved>
<QoS Reserved> = <Traffic> <QoS Class> <Priority> <S>
Any subset of the QSPEC parameters on the right hand side of the
equal sign can be included in the <QoS Reserved> object. These
parameters describe the QoS reserved by the QNEs along the data path.
<Traffic>, <QoS Class> and <Priority> are defined above.
<S> = slack term, which is the difference between desired delay and
delay obtained by using bandwidth reservation, and which is used to
reduce the resource reservation for a flow [RFC2212]. This is an
QSPEC-2 parameter.
5.3.2.4 <Minimum QoS>
<Minimum QoS> = <Traffic> <QoS Class> <Priority>
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Any subset of the QSPEC parameters on the right hand side of the
equal sign can be included in the <Minimum QoS> object.
<Minimum QoS> does not have an equivalent in RSVP. It allows the QNI
to define a range of acceptable QoS levels by including both the
desired QoS value and the minimum acceptable QoS in the same message.
It is a read-only QSPEC object. The desired QoS is included with a
<QoS Desired> and/or a <QoS Available> QSPEC object seeded to the
desired QoS value. The minimum acceptable QoS value MAY be coded in
the <Minimum QoS> QSPEC object. As the message travels towards the
QNR, <QoS Available> is updated by QNEs on the path. If its value
drops below the value of <Minimum QoS> the reservation fails and is
aborted. When this method is employed, the QNR SHOULD signal back to
the QNI the value of <QoS Available> attained in the end, because the
reservation MAY need to be adapted accordingly.
6. QSPEC Processing & Procedures
The QSPEC is opaque to the QoS NSLP processing, as described in
[QoS-SIG]. The QSPEC control information and the QoS description are
interpreted by the QNE's RMF and may be modified by the RMF. This
section discusses QSPEC processing and how the QNE/RMF interprets
QSPEC parameters, stacks QSPECs, determines reservation
success/failure, and signals QSPEC errors and INFO_SPEC
notifications. An example of QSPEC processing is given in the final
sub-section.
6.1 Interpreting QSPEC Parameters
The QSPEC contains a QOSM ID that identifies which QOSM is being
signaled by the QNI. If a QSPEC arrives at a QNE that does not
support the QOSM being signaled, it must still interpret the QSPEC
content, at least to a basic degree, since QSPEC-1 parameters have
been defined as a common language for interoperability of different
QOSMs being support in different domains. That is, a QNE must at
least interpret all the QSPEC-1 parameters in a QSPEC even if it does
not support the corresponding QOSM.
Hence a QNE must either a) strictly interpret a QSPEC parameter, or
b) remap, approximate, or otherwise not strictly interpret the QSPEC
parameter. Here 'strictly interpret' means that the parameter is
implemented by the QNE/RMF according to the commonly accepted
procedures as specified by references given for each QSPEC parameter
in this document. In the latter case of a remapped QSPEC parameter,
the QNE/RMF must raise the remapped parameter R-flag and non-QOSM-hop
Q-flag defined in Section 6.3.2, and the remapping must be
specified in the QOSM specification. For example, in case a), a
<Token Bucket> parameter must be strictly interpreted as a token
bucket, and in case b), a <token Bucket> parameter may be remapped to
a <Bandwidth> parameter.
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In the latter case b), the remapping of the <Token Bucket> to
<Bandwidth> must be specified in the QOSM specification document.
For example, QOSM X exclusively uses the parameter <Bandwidth>. It
must define a mapping of the QSPEC-1 parameter <Token Bucket>.
The mapping consists of interpreting the Token Bucket Rate as
the <Bandwidth> parameter and disregarding the other Token Bucket
parameters. Clearly, some information contained in the <Token
Bucket> parameter is lost by this mapping, and the resulting QoS may
not be quite what was intended by the QNI. Therefore, QOSM X also
specifies that the non-QOSM-hop Q-flag be raised. Thus, a QNE using
QOSM X is able to make an informed decision whether to admit a
reservation described in terms of <Token Bucket>, and at the same
time (by means of the non-QOSM-hop Q-flag) signals to the QNI/QNR
that the exact intention of the QNI may not be met.
Other examples of remapping QSPEC-1 parameters are as follows:
- <traffic>: bandwidth remapped to token bucket rate and the other
token bucket parameters set to zero or some large value
- <QoS class>: DSTE QoS class to PHB QoS class
- <QoS class>: Y.1541 QoS class remapped to PHB QoS class
- <priority>: admission/RPH = high priority remapping to
admission/RPH = normal priority
Remapping between different QSPEC-1 parameter types, e.g., from <QoS
Class> to <traffic>, is more complex but is allowed if defined in the
QOSM specification document. If a remapping for a QSPEC-1 parameter
is not defined in the QOSM specification document, the default is
that the QOSM must strictly interpret the QSPEC-1 parameter.
In some cases a QNE may need to reject a reservation because of
possible incompatibilities among QSPEC parameters. One example is
that some parameters may be illegal (e.g., preemption in the U.S.
PSTN). In such a case a QNE must reject a reservation where
preemption cannot be accommodated.
6.2 QSPEC Stacking & Tunneling
A QNE at the edge of a local domain may either a) translate the
initiator QSPEC into a local QSPEC and stack the local QSPEC on top
of the initiator QSPEC in the RESERVE message, or b) tunnel the
initiator QSPEC through the local domain and reserve resources by
generating a new RESERVE message through the local domain containing
the local QSPEC. In either case the initiator QSPEC parameters are
interpreted at the local domain edges.
Therefore when reserving resources with a RESERVE message, a local
QSPEC MAY be pushed on the stack at the ingress edge of a local QoS
domain, in order to describe the requested resources in a
domain-specific manner. Here the terms 'ingress' and 'egress' refer
to the direction of the RESERVE message rather than the direction of
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the flow. Also, the local QSPEC is popped from the stack at the
egress edge of the local QoS domain. When a RESPONSE message
corresponding to the RESERVE message arrives on its way back at the
egress edge, a local QSPEC MUST again be generated, describing the
reserved resources in a domain-specific manner. This local QSPEC is
popped from the stack at the ingress edge.
A QoS NSLP message can contain a stack of at most two QSPECs. The
first on the stack is the initiator QSPEC. This is a QSPEC provided
by the QNI, which travels end-to-end, and therefore the stack always
has at least depth 1. QSPEC parameters MUST NOT be deleted from or
added to the initiator QSPEC. In addition, the stack MAY contain a
local QSPEC stacked on top of the initiator QSPEC. A QNE only
considers the topmost QSPEC.
QNEs generating a local QSPEC for the purpose of stacking or
tunneling have two possible approaches to processing the QSPEC-1
parameters in the initiator QSPEC:
a) The local QSPEC includes all QSPEC-1 parameters in the initiator
QSPEC (possibly remapped according to the local QOSM). For
example, the initiator QSPEC specifies a token bucket parameter,
and it is remapped into the bandwidth parameter in the local
QSPEC. The ingress QNE in the local domain does not populate
the token bucket parameter in the local QSPEC, rather it populates
the bandwidth parameter is the local QSPEC and stacks the local
QSPEC on top of the initiator QSPEC. The local QSPEC is
interpreted by the QNEs in the local domain, and the egress QNE in
the local domain populates token bucket in the initiator QSPEC
with just the bandwidth parameter for the token bucket (and not
the other token bucket parameters). Note that without QSPEC
stacking or tunneling, all QNEs must do this same thing in the
local domain, that is, interpret all QSPEC-1 parameters in the
initiator QSPEC, which would include remapping the token bucket
parameter to the bandwidth parameter.
b) The local QSPEC does not include all QSPEC-1 parameters in the
initiator QSPEC, but the egress QNE in the local domain has
information configured that allows it to update/process the
QSPEC-1 parameters in the initiator QSPEC accordingly. In this
case the local QSPEC may carry neither the bandwidth nor token
bucket in the above example, if the egress QNE in the local domain
has some other means to interpret the token bucket parameter of
the initiator QSPEC (e.g., local data base or controller).
For example, in a DiffServ domain with a bandwidth broker, the
bandwidth broker could inform the egress QNE, or if RSVP is used
in the local domain, the information could be obtained from RSVP,
or if it is an MPLS domain where LSPs have a particular bandwidth,
then the egress QNE knows what is available by counting the
reservations that come out of the tunnel. Normally the egress QNE
in the local domain interprets the initiator QSPEC parameters,
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since doing this in the ingress QNE may require the ingress QNE to
inform the egress QNE that it has done this (this is not precluded
however).
Note that in the above cases the Q-Flag is set whenever a QOSM is
encountered on the path that is different from the Initiator QSPEC,
e.g., the Q-Flag is set in both cases a) and b). Also, the R-flag is
set for any Initiator QSPEC parameter that is remapped.
QSPEC stacking with a local QSPEC saves interior QNEs from
individually interpreting the initiator QSPEC within their local
QOSM. Instead, the ingress/egress QNEs do this for them, and in
this way consistent processing within a domain is simplified. That
is, the equivalent normal behavior is achieved in the local domain as
if all QNEs in the domain interpret the initiator QSPEC individually.
6.3 Reservation Success/Failure, QSPEC Error Codes, & INFO_SPEC
Notification
A reservation may not be successful for several reasons:
- a reservation may fail because the desired resources are not
available. This is a reservation failure condition.
- a reservation may fail because the QSPEC is erroneous, or because
of a QNE fault. This is an error condition.
A reservation may be successful even though some parameters could not
be interpreted or updated properly:
- a QSPEC parameter cannot be interpreted because it is an unknown
QSPEC-2 parameter type. This is a QSPEC parameter not supported
condition. The reservation however does not fail. The QNI can
still decide whether to keep or tear down the reservation depending
on the procedures specified by the QNI's QOSM.
- a QSPEC parameter value is remapped, approximated, or otherwise not
strictly interpreted. This is a QSPEC parameter remapped
condition. The reservation however does not fail. The QNI can
still decide whether to keep or tear down the reservation.
The following sections describe the handling of unsuccessful
reservations and reservations where some parameters could not be met
in more detail, as follows:
- details on flags used inside the QSPEC to convey information on
success or failure of individual parameters. The formats and
semantics of all flags are given in Section 7.
- the content of the INFO_SPEC [QoS-SIG], which carries a code
indicating the outcome of reservations.
- the generation of a RESPONSE message to the QNI containing both
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QSPEC and INFO_SPEC objects.
6.3.1 Reservation Failure & Error E-Flag
The QSPEC parameters each have a 'reservation failure error E-flag'
to indicate which (if any) parameters could not be satisfied. When a
resource cannot be satisfied for a particular parameter, the QNE
detecting the problem raises the E-flag in this parameter. Note that
all QSPEC parameters MUST be examined by the RMF and appropriately
flagged. Additionally, the E-flag in the corresponding QSPEC object
MUST be raised. If the reservation failure problem cannot be located
at the parameter level, only the E-flag in the QSPEC object is
raised.
When an RMF cannot interpret the QSPEC because the coding is
erroneous, it raises corresponding reservation failure E-flags in the
QSPEC. Normally all QSPEC parameters MUST be examined by the RMF
and the erroneous parameters appropriately flagged. In some cases,
however, an error condition may occur and the E-flag of the
error-causing QSPEC parameter is raised (if possible), but the
processing of further parameters may be aborted.
Note that if the QSPEC and/or any QSPEC parameter is found to be
erroneous, then any QSPEC parameters not satisfied are ignored and
the E-Flags in the QSPEC object MUST NOT be set for those parameters
(unless they are erroneous).
Whether E-flags denote reservation failure or error can be determined
by the corresponding error code in the INFO_SPEC in QoS NSLP, as
discussed below.
6.3.2 Non-QOSM-Hop Q-Flag & Remapped QSPEC Parameter R-flag
The non-QOSM-hop Q-flag is a flag bit telling the QNR (or QNI in a
RESPONSE message) whether or not the initiator QOSM is supported by
each QNE in the path between the QNI and QNR. A QNE MUST set the
non-QOSM-hop Q-flag parameter if it does not support the relevant
initiator QOSM specification. If the QNR finds this bit set, at
least one QNE along the data transmission path between the QNI and
QNR can not support the specified initiator QOSM. In a local QSPEC,
the non-QOSM-hop Q-flag refers to the QoS NSLP peers of the local
QOSM domain. When the local QSPEC is popped, the R-Flags of the
corresponding remapped parameters in the initiator QSPEC must be
raised. The RESERVE message should continue to be forwarded with the
non-QOSM-hop Q-flag set, and the QNI has the option of tearing the
reservation.
A QNE detecting that one or more QSPEC parameters have to be
remapped, approximated, or otherwise not strictly interpreted MUST
set the remapped QSPEC parameter R-flag for each QSPEC parameter that
is remapped. The RESERVE message should continue to be forwarded
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with the R-flags set, and the QNI has the option of tearing the
reservation. This condition might occur, for example, when a QNE's
local QOSM is different from the QNI's initiator QOSM, and the local
QOSM specifies that some QSPEC parameters are to be remapped. See
the example in Appendix A for an illustration of this condition. The
R-flag may be interpreted by the QNI, ingress QNE (start of tunnel)
in a domain), egress QNE (end of tunnel) in a local domain, or QNR.
When a RESERVE message is tunneled through a local domain, QNEs
inside the domain cannot update read-write QSPEC parameters in the
initiator QSPEC. The egress QNE in the local domain either a) is
configured to have the knowledge to interpret the parameters
correctly, or b) cannot accurately interpret the parameters. In the
latter case the egress QNE in the local domain MUST set the R-flag
for each QSPEC parameter it cannot interpret to tell the QNI (or QNR)
that the information contained in the read-write parameter is most
likely incorrect (or a lower bound). Note that if possible the edge
QNEs in the local domain must interpret the QSPEC-1 parameters
populated in the initiator QSPEC and MUST NOT use the R-flag to
'ignore' a QSPEC-1 parameter populated in the initiator QSPEC.
6.3.3 QSPEC Parameter Not Supported N-Flag
When the QOSM ID is not known to a QNE, it MUST interpret at least
the QSPEC-1 parameters.
Each QSPEC-2 parameter has an associated 'not supported N-flag'. If
the not supported N-flag is set, then at least one QNE along the data
transmission path between the QNI and QNR cannot interpret the
specified QSPEC-2 parameter. A QNE MUST set the not supported N-flag
if it cannot interpret the QSPEC-2 parameter. In that case the
message should continue to be forwarded but with the N-flag set, and
the QNI has the option of tearing the reservation.
If a QNE in the path does not support a QSPEC-2 parameter, e.g.,
<Path Latency>, and sets the N-flag, then downstream QNEs that
support the parameter SHOULD still update the parameter, even if the
N-flag is set. However, the presence of the N-flag will make the
cumulative value unreliable, and the QNI/QNR decides whether or not
to accept the reservation with the N-flag set.
6.3.4 INFO_SPEC Coding of Reservation Outcome
As prescribed by [QoS-SIG], the RESPONSE message always contains the
INFO_SPEC with an appropriate 'error' code. It usually also contains
a QSPEC with QSPEC objects, as described in Section 6.3 on QSPEC
Procedures. The RESPONSE message MAY omit the QSPEC in case of a
successful reservation.
The following guidelines are provided in setting the error codes in
the INFO_SPEC, based on the codes provided in Section 5.1.3.6 of
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[QoS-SIG]:
- INFO_SPEC error class 0x02 (Success) / 0x01 (Reservation Success):
This code is set when all QSPEC parameters have been satisfied
(possibly with remapping). In this case no E-Flag is set, however
the Q-flag, N-flags or R-flags may be set.
- INFO_SPEC error class 0x04 (Transient Failure) / 0x08 (Reservation
Failure):
This code is set when at least one parameter could not be
satisfied. E-flags are set for the parameters that could not be
satisfied up to the QNE issuing the RESPONSE message. In this case
QNEs receiving the RESPONSE message MUST remove the corresponding
reservation.
- INFO_SPEC error class 0x03 (Protocol Error) / 0x0c (Malformed
QSPEC):
Some QSPEC parameters had associated errors, E-Flags are set for
parameters that had errors, and the RMF rejects the reservation.
- INFO_SPEC error class 0x06 (QoS Model Error):
QOSM error codes can be defined by QOSM specification documents. A
registry is defined in Section 9 IANA Considerations.
6.3.5 QNE Generation of a RESPONSE message
- Successful Reservation Condition
When a RESERVE message arrives at a QNR and no E-Flag is set, the
reservation is successful. A RESPONSE message may be generated with
INFO_SPEC code 'Reservation Success' as described above and in the
QSPEC Procedures described in Section 6.4.
A raised non-QOSM-hop Q-flag in the QSPEC of the RESERVE message
indicates that a local QOSM is encountered that differs from the
initiator QOSM and that some QSPEC parameters may have been remapped,
approximated, or otherwise not strictly interpreted, as indicated by
raised R-flags on these QSPEC parameters. The non-QOSM-hop Q-flag
and R-flags are sent back in the RESPONSE message and the QNI then
makes the final determination as to whether to continue or tear down
the reservation that has been established. A QOSM specification may
specify the conditions for rejecting a reservation under such
conditions. However, in the absence of such procedures, the default
condition SHOULD be 'success' if all QSPEC parameters are met and
'reservation failure' if one or more QSPEC parameters are not met.
- Reservation Failure Condition
When a QNE detects that a reservation failure occurs for at least one
parameter, the QNE sets the E-Flags for the QSPEC parameters and
QSPEC object that failed to be satisfied. According to [QoS-SIG],
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the QNE behavior depends on whether it is stateful or not. When a
stateful QNE determines the reservation failed, it formulates a
RESPONSE message that includes an INFO_SPEC with the 'reservation
failure' error code and QSPEC object. The QSPEC in the RESPONSE
message includes the failed QSPEC parameters marked with the E-Flag
to clearly identify them.
The default action for a stateless QoS NSLP QNE that detects a
reservation failure condition is that it MUST continue to forward the
RESERVE message to the next stateful QNE, with the E-Flags
appropriately set for each QSPEC parameter. The next stateful QNE
then formulates the RESPONSE message as described above.
- Malformed QSPEC Error Condition
When a stateful QNE detects that one or more QSPEC parameters are
erroneous, the QNE sets the error code 'malformed QSPEC' in the
INFO_SPEC. In this case the QSPEC object with the E-Flags
appropriately set for the erroneous parameters is returned within
the INFO_SPEC object. The QSPEC object can be truncated or fully
included within the INFO_SPEC.
According to [QoS-SIG], the QNE behavior depends on whether it is
stateful or not. When a stateful QNE determines a malformed QSPEC
error condition, it formulates a RESPONSE message that includes an
INFO_SPEC with the 'malformed QSPEC' error code and QSPEC object.
The QSPEC in the RESPONSE message includes, if possible, only the
erroneous QSPEC parameters and no others. The erroneous QSPEC
parameter(s) are marked with the E-Flag to clearly identify them. If
QSPEC parameters are returned in the INFO-SPEC that are not marked
with the E-flag, then any values of these parameters are irrelevant
and MUST be ignored by the QNI.
The default action for a stateless QoS NSLP QNE that detects a
Malformed QSPEC error condition is that it MUST continue to forward
the RESERVE message to the next stateful QNE, with the E-Flags
appropriately set for each QSPEC parameter. The next stateful QNE
will then act as described in [QoS-SIG].
A 'malformed QSPEC' error code takes precedence over the 'reservation
failure' error code, and therefore the case of reservation failure
and QSPEC/RMF error conditions are disjoint and the same E-Flag can
be used in both cases without ambiguity.
6.3.6 Domains Supporting a Different Local QOSM than the QNI
A domain supporting a different local QOSM than the QNI domain
inspects all QSPEC-1 parameters and consults its local QOSM as to how
to interpret these parameters and decides whether it can accommodate
the flow. This analysis can have these various outcomes:
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a) RMF determines that it can accommodate the flow with the QoS
specified by the QNI,
b) RMF determines that some initiator QSPEC parameters cannot be
satisfied with the available resources, and marks the appropriate
error flags (see Section 6.3.1), but does not reject the
reservation, or
c) RMF determines that some initiator QSPEC parameters cannot be
satisfied with the available resources, marks the appropriate
error flags (see Section 6.3.1), and also rejects the reservation.
The QNE also in any event sets the non-QOSM-hop Q-flag, as
described in Section 6.3.2.
6.3.7 Special Cases of QSPEC Stacking
When an unsuccessful reservation problem occurs inside a local domain
where QSPEC stacking is used, only the topmost (local) QSPEC is
affected (e.g. E-flags are raised, etc.). The initiator QSPEC at the
bottom is untouched. When the message (RESPONSE in case of stateful
QNEs, RESERVE in case of stateless QNEs) however reaches the edge of
the stacking domain, the local QSPEC is popped, and its content,
including flags, is translated into the initiator QSPEC.
6.4 QSPEC Procedures
While the QSPEC template aims to put minimal restrictions on usage of
QSPEC objects in <QoS Description>, interoperability between QNEs and
between QOSMs must be ensured. We therefore give below an exhaustive
list of QSPEC object combinations for the message sequences described
in QoS NSLP [QoS-SIG]. A specific QOSM may prescribe that only a
subset of the procedures listed below may be used.
Note that QoS NSLP does not mandate the usage of a RESPONSE message.
In fact, a RESPONSE message will only be generated if the QNI
includes an RII (Request Identification Information) in the RESERVE
message. Some of the QSPEC procedures below, however, are only
meaningful when a RESPONSE message is possible. The QNI SHOULD in
these cases include an RII.
6.4.1 Sender-Initiated Reservations
Here the QNI issues a RESERVE message, which may be replied to by a
RESPONSE message. The following 3 cases for QSPEC object usage
exist:
ID | RESERVE | RESPONSE
---------------------------------------------------------------
1 | QoS Desired | QoS Reserved
2 | QoS Desired, QoS Avail. | QoS Reserved, QoS Avail.
3 | QoS Desired, QoS Avail., Min. QoS | QoS Reserved, QoS Avail.
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Case 1:
If only QoS Desired is included in the RESERVE message, the implicit
assumption is that exactly these resources must be reserved. If this
is not possible the reservation fails. The parameters in QoS
Reserved are copied from the parameters in QoS Desired. If the
reservation is successful, the RESPONSE message can be omitted in
this case. If a RESPONSE message was requested by a QNE on the
path, the QSPEC in the RESPONSE message can be omitted.
Case 2:
When QoS Available is included in the RESERVE message also, some
parameters will appear only in QoS Available and not in QoS Desired.
It is assumed that the value of these parameters is collected for
informational purposes only (e.g. path latency).
However, some parameters in QoS Available can be the same as in QoS
Desired. For these parameters the implicit message is that the QNI
would be satisfied by a reservation with lower parameter values than
specified in QoS Desired. For these parameters, the QNI seeds the
parameter values in QoS Available to those in QoS Desired (except for
cumulative parameters such as <path latency>).
Each QNE remaps or approximately interprets the parameters in QoS
Available according to its current capabilities. Reservations in
each QNE are hence based on current parameter values in QoS Available
(and additionally those parameters that only appear in QoS Desired).
The drawback of this approach is that, if the resulting resource
reservation becomes gradually smaller towards the QNR, QNEs close to
the QNI have an oversized reservation, possibly resulting in
unnecessary costs for the user. Of course, in the RESPONSE the QNI
learns what the actual reservation is (from the QoS RESERVED object)
and can immediately issue a properly sized refreshing RESERVE. The
advantage of the approach is that the reservation is performed in
half-a-roundtrip time.
The QSPEC parameter IDs and values included in the QoS Reserved
object in the RESPONSE message MUST be the same as those in the QoS
Desired object in the RESERVE message. For those QSPEC parameters
that were also included in the QoS Available object in the RESERVE
message, their value is copied into the QoS Desired object. For the
other QSPEC parameters, the value is copied from the QoS Desired
object (the reservation would fail if the corresponding QoS could
not be reserved).
All parameters in the QoS Available object in the RESPONSE message
are copied with their values from the QoS Available object in the
RESERVE message (irrespective of whether they have also been copied
into the QoS Desired object). Note that the parameters in the QoS
Available object are read-write in the RESERVE message, whereas they
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are read-only in the RESPONSE message.
In this case, the QNI SHOULD request a RESPONSE message since it will
otherwise not learn what QoS is available.
Case 3:
This case is handled as case 2, except that the reservation fails
when QoS Available becomes less than Minimum QoS for one parameter.
If a parameter appears in the QoS Available object but not in the
Minimum QoS object it is assumed that there is no minimum value for
this parameter.
Regarding QSPEC Control Information, the default rule is that all
QSPEC parameters that have been included in the RESERVE message by
the QNI are also included in the RESPONSE message by the QNR with the
value they had when arriving at the QNR. When traveling in the
RESPONSE message, all QSPEC Control Information parameters are
read-only. Note that a QOSM specification may define its own
QOSM-specific Control Information parameters and processing rules.
Also in this case, the QNI SHOULD request a RESPONSE message since it
will otherwise not learn what QoS is available.
6.4.2 Receiver-Initiated Reservations
Here the QNR issues a QUERY message which is replied to by the QNI
with a RESERVE message if the reservation was successful. The QNR in
turn sends a RESPONSE message to the QNI. The following 3 cases for
QSPEC object usage exist:
ID| QUERY | RESERVE | RESPONSE
---------------------------------------------------------------------
1 |QoS Des. | QoS Des. | QoS Res.
2 |QoS Des.,Min. QoS | QoS Des.,QoS Avl.,(Min QoS)| QoS Res.,QoS Avl.
3 |Qos Des.,QoS Avl. | QoS Des.,QoS Avl. | QoS Res.
Cases 1 and 2:
The idea is that the sender (QNR in this scenario) needs to inform
the receiver (QNI in this scenario) about the QoS it desires. To
this end the sender sends a QUERY message to the receiver including a
QoS Desired QSPEC object. If the QoS is negotiable it additionally
includes a (possibly zero) Minimum QoS object, as in Case 2.
The RESERVE message includes the QoS Available object if the sender
signaled that QoS is negotiable (i.e. it included the Minimum QoS
object). If the Minimum QoS object received from the sender is
included in the QUERY message, the QNR also includes the Minimum QoS
object in the RESERVE message.
For a successful reservation, the RESPONSE message in case 1 is
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optional (as is the QSPEC inside). In case 2 however, the RESPONSE
message is necessary in order for the QNI to learn about the QoS
available.
Case 4:
This is the 'RSVP-style' scenario. The sender (QNR in this scenario)
issues a QUERY message with a QoS Desired object informing the
receiver (QNI in this scenario) about the QoS it desires as above.
It also includes a QoS Available object to collect path properties.
Note that here path properties are collected with the QUERY message,
whereas in the previous case 2 path properties were collected in the
RESERVE message.
Some parameters in the QoS Available object may the same as in the
QoS Desired object. For these parameters the implicit message is
that the sender would be satisfied by a reservation with lower
parameter values than specified in QoS Desired.
It is possible for the QoS Available object to contain parameters
that do not appear in the QoS Desired object. It is assumed that the
value of these parameters is collected for informational purposes
only (e.g. path latency). Parameter values in the QoS Available
object are seeded according to the sender's capabilities. Each QNE
remaps or approximately interprets the parameter values according to
its current capabilities.
The receiver (QNI in this scenario) signals the QoS Desired object as
follows: For those parameters that appear in both the QoS Available
object and QoS Desired object in the QUERY message, it takes the
(possibly remapped) QSPEC parameter values from the QoS Available
object. For those parameters that only appear in the QoS Desired
object, it adopts the parameter values from the QoS Desired object.
The parameters in the QoS Available QSPEC object in the RESERVE
message are copied with their values from the QoS Available QSPEC
object in the QUERY message. Note that the parameters in the QoS
Available object are read-write in the QUERY message, whereas they
are read-only in the RESERVE message.
The advantage of this model compared to the sender-initiated
reservation is that the situation of over-reservation in QNEs close
to the QNI as described above does not occur. On the other hand, the
QUERY message may find, for example, a particular bandwidth is not
available. When the actual reservation is performed, however, the
desired bandwidth may meanwhile have become free. That is, the 'RSVP
style' may result in a smaller reservation than necessary.
Regarding QSPEC Control Information in receiver-initiated
reservations, the sender includes all QSPEC Control Information it
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cares about in the QUERY message. Read-write parameters are updated
by QNEs as the QUERY message travels towards the receiver. The
receiver includes all QSPEC Control Information parameters arriving
in the QUERY message also in the RESERVE message, as read-only
parameters with the value they had when arriving at the receiver.
Again, QOSM-specific Control Information parameters and procedures
may be defined in QOSM specification documents.
Also in this scenario, the QNI SHOULD request a RESPONSE message
since it will otherwise not learn what QoS is available.
6.4.3 Resource Queries
Here the QNI issues a QUERY message in order to investigate what
resources are currently available. The QNR replies with a RESPONSE
message.
ID | QUERY | RESPONSE
--------------------------------------------
1 | QoS Available | QoS Available
Note that the QoS Available object when traveling in the QUERY
message is read-write, whereas in the RESPONSE message it is
read-only.
6.4.4 Bidirectional Reservations
On a QSPEC level, bidirectional reservations are no different from
uni-directional reservations, since QSPECs for different directions
never travel in the same message.
6.4.5 Preemption
A flow can be preempted by a QNE based on the values of the QSPEC
Priority parameter (see Section 7.2.4). In this case the reservation
state for this flow is torn down in this QNE, and the QNE sends a
NOTIFY message to the QNI, as described in [QoS-SIG]. No QSPEC is
carried in the NOTIFY message. The NOTIFY message carries only the
Session ID and a INFO_SPEC with the error code as described in
[QoS-SIG]. The QNI would normally tear down the preempted
reservation by sending a RESERVE message with the TEAR flag set using
the SII of the preempted reservation. However, the QNI can follow
other procedures as specified in its QOSM specification document.
6.5 QSPEC Extensibility
This document defines both QSPEC-1 and QSPEC-2 parameters. The
set of QSPEC-1 parameters defined herein is at this point in time
considered complete. The QSPEC-2 parameters in this document
correspond to some of the QSPEC-2 parameters considered in QOSMs
currently being defined.
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Additional QSPEC-1 parameters may be defined in the future. However,
since this requires an update of all QNEs, this should be considered
carefully. The definition of new QSPEC-1 parameter requires
standards action and an update of this document. Such an update also
needs a new QSPEC version number. Furthermore, all QOSM definitions
must be updated to include how the new QSPEC-1 parameter is to be
interpreted in the respective QOSM.
Additional QSPEC-2 parameters MAY need to be defined in the future
and are defined in separate informational documents specific to a
given QOSM. For example, QSPEC-2 parameters are defined in
[RMD-QOSM] and [Y.1541-QOSM].
Guidelines on the technical criteria to be followed in evaluating
requests for new codepoint assignments for QSPEC objects and QSPEC
parameters are given in Section 9 (IANA Considerations).
Guidelines on the technical criteria to be followed in evaluating
requests for new codepoint assignments beyond QSPEC objects and
QSPEC parameters for the NSIS protocol suite are given in a separate
NSIS extensibility document [NSIS-EXTENSIBILITY].
7. QSPEC Functional Specification
This section defines the encodings of the QSPEC parameters and QSPEC
control information defined in Section 5. We first give the general
QSPEC formats and then the formats of the QSPEC objects and
parameters.
Note that all QoS description parameters can be either read-write or
read-only, depending on which object and which message they appear
in. All parameters in the QoS Desired object, QoS Reserved object,
and Minimum QoS object are read-only for all messages. All
parameters in the QoS Available object are normally read-write
parameters. However, as discussed in Section 5.2.2, the parameters
in the QoS Available object are read-write when the QoS Available
object appears for the first time e.g. in the RESERVE message or
QUERY message from QNI to QNR. However, on its way back, all
parameters in the <QoS Available> object are read-only, e.g., in the
RESPONSE message or RESERVE message from QNR to QNI. For QSPEC
control information parameters, the property of being read-write or
read-only is parameter specific. Note that the only control
information parameter specified in this document is the <excess
treatment> parameter, which is a read-only parameter.
Network byte order ('big-endian') for all 16- and 32-bit integers, as
well as 32-bit floating point numbers, are as specified in [RFC1832,
IEEE754, NETWORK-BYTE-ORDER].
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7.1 General QSPEC Formats
The format of the QSPEC closely follows that used in GIST [GIST] and
QoS NSLP [QoS-SIG]. Every object (and parameter) has the following
general format:
o The overall format is Type-Length-Value (in that order).
o Some parts of the type field are set aside for control flags.
o Length has the units of 32-bit words, and measures the length of
Value. If there is no Value, Length=0. The Object length
excludes the header.
o Value is a whole number of 32-bit words. If there is any padding
required, the length and location MUST be defined by the
object-specific format information; objects that contain variable
length types may need to include additional length subfields to do
so.
o Any part of the object used for padding or defined as reserved("r")
MUST be set to 0 on transmission and MUST be ignored on reception.
o Empty QSPECs and empty QSPEC Objects MUST NOT be used.
o Duplicate objects, duplicate parameters, and/or multiple
occurrences of a parameter MUST NOT be used.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Common QSPEC Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// QSPEC Control Information //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// QSPEC QoS Description Objects //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Common QSPEC Header is a fixed 4-byte long object containing the
QOSM ID and an identifier for the QSPEC Procedure (see Section 6.4):
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vers. | QOSM ID | QSPEC Proc. | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note that a length field is not necessary since the overall length of
the QSPEC is contained in the higher level QoS NSLP data object.
Vers.: Identifies the QSPEC version number. It is assigned by IANA.
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QOSM ID: Identifies the particular QOSM being used by the QNI. It is
assigned by IANA.
QSPEC Proc.: Is composed of two times 4 bits. The first set of bits
identifies the Message Sequence, the second set
identifies the QSPEC Object Combination used for this
particular message sequence:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|Mes.Sq |Obj.Cmb|
+-+-+-+-+-+-+-+-+
The Message Sequence field can attain the following
values:
0: Sender-Initiated Reservations
1: Receiver-Initiated Reservations
2: Resource Queries
The Object Combination field can take the values between
1 and 3 indicated in the tables in Section 6.4:
Message Sequence: 0
Object Combination: 1, 2, 3
Semantic: see table in Section 6.4.1
Message Sequence: 1
Object Combination: 1, 2, 3
Semantic: see table in Section 6.4.2
Message Sequence: 2
Object Combination: 1, 2, 3
Semantic: see table in Section 6.4.3
The QSPEC Control Information is a variable length object containing
one or more parameters. The QSPEC Objects field is a collection of
QSPEC objects (QoS Desired, QoS Available, etc.), which share a
common format and each contain several parameters.
Both the QSPEC Control Information object and the QSPEC QoS objects
share a common header format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E|Q|r|r| Object Type |r|r|r|r| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E Flag: Set if an error occurs on object level
Q Flag: NON QOSM Hop flag: This field is set to 1 if a QOSM different
from the initiator QOSM is encountered by the QNE.
Object Type = 0: control information (read-only/read-write status is
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parameter specific)
= 1: QoS Desired (parameters are all read-only)
= 2: QoS Available (parameters are either all read-write
rr all read-only; see Section 5.2.2)
= 3: QoS Reserved (parameters are all read-only)
= 4: Minimum QoS (parameters are all read-only)
Note that parameters contained in QoS Description objects are all
read-write or all read-only, as specified above. In the Control
Information object, read-only or read-write is parameter specific.
The r bits are reserved.
Each QSPEC-1 or QSPEC-2 parameter within an object is similarly
encoded in TLV format using a similar parameter header:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M|E|N|R| Parameter ID |r|r|r|r| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
M Flag: When set indicates the subsequent parameter is a QSPEC-1
parameter and MUST be interpreted. Otherwise the parameter is
QSPEC-2 and can be ignored if not understood.
E Flag: When set indicates either a) a reservation failure where the
QSPEC parameter is not met, or b) an error occurred when this
parameter was being interpreted (see Section 6.3.1).
N Flag: Not-supported QSPEC parameter flag (see Section 6.3.3).
For QSPEC-1 parameters the value of this flag is always zero.
R Flag: Remapped, approximated, or otherwise not strictly interpreted
QSPEC parameter flag (see Section 6.3.2)
Parameter ID: Assigned to each parameter (see below)
Parameters are usually coded individually, for example, the <Excess
Treatment> parameter (Section 7.2.1). However, it is also possible
to combine several sub-parameters into one parameter field, which is
called 'container coding'. This coding is useful if either a) the
sub-parameters always occur together, as for example the several
sub-parameters that jointly make up the token bucket, or b) in order
to make coding more efficient when the length of each sub-parameter
value is much less than a 32-bit word (as for example described in
[RMD-QOSM]) and to avoid header overload. When a container is
defined, the Parameter ID and the M, E, N, and R flags refer to the
container. Examples of container parameters are <Traffic>, <QoS
Class>, <Priority>, and <Token Bucket>, as specified below, and the
PHR container parameter specified in [RMD-QOSM].
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7.2 QSPEC-1 Parameter Coding
7.2.1 <Excess Treatment> Parameter
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|0|R| 1 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Excess Trtmnt | Remark Value | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Excess Treatment: Indicates how the QNE SHOULD process out-of-profile
traffic, that is, traffic not covered by the <Traffic> parameter.
The excess treatment parameter is set by the QNI. It is a read-only
parameter. Allowed values are as follows:
0: drop
1: shape
2: remark
3: no metering or policing is permitted
The default excess treatment in case that none is specified is that
there are no guarantees to excess traffic, i.e. a QNE can do whatever
it finds suitable.
When excess treatment is set to 'drop', all marked traffic MUST be
dropped by the QNE/RMF.
When excess treatment is set to 'shape', it is expected that the
QoS Desired object carries a token bucket parameter. Excess traffic
is to be shaped to this token bucket. When the shaping causes
unbounded queue growth at the shaper traffic can be dropped.
When excess treatment is set to 'remark', the excess treatment
parameter MUST carry the remark value, and the remark values and
procedures MUST be specified in the QOSM specification document.
For example, packets may be remarked to drop remarked to pertain to a
particular QoS class". In the latter case, remarking relates to a
DiffServ-type model, where packets arrive marked as belonging to a
certain QoS class, and when they are identified as excess, they
should then be remarked to a different QoS Class.
If 'no metering or policing is permitted' is signaled, the QNE should
accept the excess treatment parameter set by the sender with special
care so that excess traffic should not cause a problem. To request
the Null Meter [RFC3290] is especially strong, and should be used
with caution.
A NULL metering application [RFC2997] would not include the traffic
profile, and conceptually it should be possible to support this with
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the QSPEC. A QSPEC without a traffic profile is not excluded by the
current specification. However, note that the traffic profile is
important even in those cases when the excess treatment is not
specified, e.g., in negotiating bandwidth for the best effort
aggregate. However, a "NULL Service QOSM" would need to be specified
where the desired QNE Behavior and the corresponding QSPEC format are
described.
As an example behavior for a NULL metering, in the properly
configured DiffServ router, the resources are shared between the
aggregates by the scheduling disciplines. Thus, if the incoming rate
increases, it will influence the state of a queue within that
aggregate, while all the other aggregates will be provided sufficient
bandwidth resources. NULL metering is useful for best effort and
signaling data, where there is no need to meter and police this data
as it will be policed implicitly by the allocated bandwidth and,
possibly, active queue management mechanism.
7.2.2 <Traffic> Parameter
<Traffic> = [<Bandwidth>] [<Token Bucket-1>]
<Bandwidth> = link bandwidth needed by flow [RFC2212, RFC2215]
<Token Bucket-1> = <r> <b> <p> <m> <MTU> [RFC2210]
The above notation means that either <Bandwidth> or <Token Bucket-1>
sub-parameters can be populated in the <Traffic> parameter and that
one and only one of them MUST be present. Note that an QSPEC-2
second token bucket QSPEC parameter <Token Bucket-2> is specified
below in Section 7.3.1. The references in the following sections
point to the normative procedures for processing the <Bandwidth> and
<Token Bucket> sub-parameters.
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The coding for the <Traffic> parameter is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|0|R| 2 |r|r|r|r| 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bandwidth (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token Bucket Rate-1 [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token Bucket Size-1 [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Data Rate-1 [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum Policed Unit-1 [m] (32-bit unsigned integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Packet Size-1 [MTU] (32-bit unsigned integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Normally only one of these sub-parameters is populated in the
<Traffic> parameter. If more than one sub-parameter is populated,
the QOSM specification document MUST give procedures for processing
multiple sub-parameters. The references in the following sections
point to the normative procedures for processing the <Bandwidth> and
<Token Bucket-1> sub-parameters.
7.2.2.1 <Bandwidth> Sub-Parameter [RFC2212, RFC2215]
The <Bandwidth> parameter MUST be nonnegative and is measured in
bytes per second and has the same range and suggested representation
as the bucket and peak rates of the <Token Bucket>. <Bandwidth> is
represented using single-precision IEEE floating point. The
representation MUST be able to express values ranging from 1 byte per
second to 40 terabytes per second. For values of this parameter only
valid non-negative floating point numbers are allowed. Negative
numbers (including "negative zero"), infinities, and NAN's are not
allowed.
A QNE MAY export a local value of zero for this parameter. A network
element or application receiving a composed value of zero for this
parameter MUST assume that the actual bandwidth available is unknown.
7.2.2.2 <Token Bucket-1> Sub-Parameters [RFC2215]
The <Token Bucket> parameters are represented by three floating point
numbers in single-precision IEEE floating point format followed by
two 32-bit integers in network byte order. The first floating point
value is the rate (r), the second floating point value is the bucket
size (b), the third floating point is the peak rate (p), the first
unsigned integer is the minimum policed unit (m), and the second
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unsigned integer is the maximum datagram size (MTU).
Note that the two sets of <Token Bucket> parameters can be
distinguished, as could be needed for example to support DiffServ
applications.
When r, b, and p terms are represented as IEEE floating point values,
the sign bit MUST be zero (all values MUST be non-negative).
Exponents less than 127 (i.e., 0) are prohibited. Exponents greater
than 162 (i.e., positive 35) are discouraged, except for specifying a
peak rate of infinity. Infinity is represented with an exponent of
all ones (255) and a sign bit and mantissa of all zeroes.
7.2.3 <QoS Class> Parameter
<QoS Class> = [<PHB Class>] [<DSTE Class Type>] [<Y.1541 QoS Class>]
The above notation means that either <PHB Class>, <DSTE Class Type>,
or <Y.1541 QoS Class> sub-parameters MAY be populated in the <QoS
Class> parameter. Normally only one of these sub-parameters is
populated in <QoS Class>. If more than one sub-parameter is
populated, the QOSM specification document MUST give procedures for
processing multiple sub-parameters. The references in the following
sections point to the normative procedures for processing the <PHB
Class>, <DSTE Class Type>, and <Y.1541 QoS Class> sub-parameters.
The coding for the <QoS Class> parameter is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|0|R| 3 |r|r|r|r| 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DSCP |0 0 0 0 0 0 0 0 0 0|DSTE Cls. Type |Y.1541 QoS Cls.|
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| QoS Class Parameters (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Class Parameters (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.2.3.1 <PHB Class> Sub-Parameter [RFC3140]
As prescribed in RFC 3140, the encoding for a single PHB is the
recommended DSCP value for that PHB, left-justified in the 16 bit
field, with bits 6 through 15 set to zero.
The encoding for a set of PHBs is the numerically smallest of the set
of encodings for the various PHBs in the set, with bit 14 set to 1.
(Thus for the AF1x PHBs, the encoding is that of the AF11 PHB, with
bit 14 set to 1.)
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0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DSCP |0 0 0 0 0 0 0 0 X 0|
+---+---+---+---+---+---+---+---+
PHBs not defined by standards action, i.e., experimental or local use
PHBs as allowed by [RFC2474]. In this case an arbitrary 12 bit PHB
identification code, assigned by the IANA, is placed left-justified
in the 16 bit field. Bit 15 is set to 1, and bit 14 is zero for a
single PHB or 1 for a set of PHBs. Bits 12 and 13 are zero.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PHD ID CODE |0 0 X 0|
+---+---+---+---+---+---+---+---+
Bits 12 and 13 are reserved either for expansion of the PHB
identification code, or for other use, at some point in the future.
In both cases, when a single PHBID is used to identify a set of PHBs
(i.e., bit 14 is set to 1), that set of PHBs MUST constitute a PHB
Scheduling Class (i.e., use of PHBs from the set MUST NOT cause
intra-microflow traffic reordering when different PHBs from the set
are applied to traffic in the same microflow). The set of AF1x PHBs
[RFC2597] is an example of a PHB Scheduling Class. Sets of PHBs
that do not constitute a PHB Scheduling Class can be identified by
using more than one PHBID.
The registries needed to use RFC 3140 already exist, see
[DSCP-REGISTRY, PHBID-CODES-REGISTRY]. Hence, no new registry needs
to be created for this purpose.
7.2.3.2 <DSTE Class Type> Sub-Parameter [RFC4124]
DSTE Class Type: Indicates the DSTE class type. Values currently
allowed are 0, 1, 2, 3, 4, 5, 6, 7. A value of 255 (all 1's) means
that the <DSTE Class Type> parameter is not used.
7.2.3.3 <Y.1541 QoS Class> Sub-Parameter [Y.1541]
Y.1541 QoS Class: Indicates the Y.1541 QoS Class. Values currently
allowed are 0, 1, 2, 3, 4, 5, 6, 7. A value of 255 (all 1's) means
that the <Y.1541 QoS Class> parameter is not used.
Class 0:
Mean delay <= 100 ms, delay variation <= 50 ms, loss ratio <= 10^-3.
Real-time, highly interactive applications, sensitive to jitter.
Application examples include VoIP, Video Teleconference.
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Class 1:
Mean delay <= 400 ms, delay variation <= 50 ms, loss ratio <= 10^-3.
Real-time, interactive applications, sensitive to jitter.
Application examples include VoIP, Video Teleconference.
Class 2:
Mean delay <= 100 ms, delay variation unspecified, loss ratio <=
10^-3. Highly interactive transaction data. Application examples
include signaling.
Class 3:
Mean delay <= 400 ms, delay variation unspecified, loss ratio <=
10^-3. Interactive transaction data. Application examples include
signaling.
Class 4:
Mean delay <= 1 sec, delay variation unspecified, loss ratio <=
10^-3. Low Loss Only applications. Application examples include
short transactions, bulk data, video streaming.
Class 5:
Mean delay unspecified, delay variation unspecified, loss ratio
unspecified. Unspecified applications. Application examples include
traditional applications of default IP networks.
Class 6:
Mean delay <= 100 ms, delay variation <= 50 ms, loss ratio <= 10^-5.
Applications that are highly sensitive to loss, such as television
transport, high-capacity TCP transfers, and TDM circuit emulation.
Class 7:
Mean delay <= 400 ms, delay variation <= 50 ms, loss ratio <= 10^-5.
Applications that are highly sensitive to loss, such as television
transport, high-capacity TCP transfers, and TDM circuit emulation.
7.2.4 <Priority> Parameter
<Priority> = [<Preemption Priority>] [<Defending Priority>]
[<Admission Priority>] [<RPH Priority>]
The above notation means that either <Preemption Priority>,
<Defending Priority>, <Admission Priority>, and/or <RPH Priority>
sub-parameters MAY be populated in the <Priority> parameter. Any or
all of these sub-parameters may be populated in the <Priority>
parameter. The references in the following sections point to the
normative procedures for processing the <Preemption Priority>,
<Defending Priority>, <Admission Priority>, and <RPH Priority>
sub-parameters.
The following cases are permissible (procedures specified in
references):
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1 parameter: <Admission Priority> [Y.1571]
2 parameters: <Admission Priority>, <RPH Priority> [RFC4412]
2 parameters: <Preemption Priority>, <Defending Priority> [RFC3181]
3 parameters: <Preemption Priority>, <Defending Priority>,
<Admission Priority> [3GPP-1, 3GPP-2, 3GPP-3]
4 parameers: <Preemption Priority>, <Defending Priority>,
<Admission Priority>, <RPH Priority> [3GPP-1, 3GPP-2,
3GPP-3]
It is permissible to have <Admission Priority> without <RPH
Priority>, but not permissible to have <RPH Priority> without
<Admission Priority> (alternatively <RPH Priority> is ignored in
instances without <Admission Priority>).
eMLPP-like functionality (as defined in [3GPP-1, 3GPP-2]) specifies
use of <Admission Priority> corresponding to the 'queuing allowed'
part of eMLPP as well as <Preemption/Defending Priority>
corresponding to the 'preemption capable' and 'may be preempted'
parts of eMLPP.
The coding for the <Priority> parameter is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|0|R| 4 |r|r|r|r| 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preemption Priority | Defending Priority |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ Admis.Priority| RPH Namespace | RPH Priority |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Priority Parameters(Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Priority Parameters(Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.2.4.1 <Preemption Priority> & <Defending Priority> Sub-Parameters
[RFC3181]
Preemption Priority: The priority of the new flow compared with the
defending priority of previously admitted flows. Higher values
represent higher priority.
Defending Priority: Once a flow is admitted, the preemption priority
becomes irrelevant. Instead, its defending priority is used to
compare with the preemption priority of new flows.
As specified in [RFC3181], <Preemption Priority> and <Defending
Priority> are 16-bit integer values and both MUST be populated if the
parameter is used.
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7.2.4.2 <Admission Priority> Sub-Parameter [Y.1571]
High priority flows, normal priority flows, and best-effort priority
flows can have access to resources depending on their admission
priority value, as described in [Y.1571], as follows:
Admission Priority:
0 - best-effort priority flow
1 - normal priority flow
2 - high priority flow
255 - not used
A reservation without an <Admission Priority> sub-parameter (i.e.,
set to 255) MUST be treated as a reservation with an <Admission
Priority> = 1.
7.2.4.3 <RPH Priority> Sub-Parameter [RFC4412]
[RFC4412] defines a resource priority header (RPH) with parameters
"RPH Namespace" and "RPH Priority" combination, and if populated is
applicable only to flows with high admission priority, as follows:
RPH Namespace:
0 - dsn
1 - drsn
2 - q735
3 - ets
4 - wps
255 - not used
RPH Priority:
Each namespace has a finite list of relative priority-values. Each
is listed here in the order of lowest priority to highest priority
(note that dsn and drsn priority values are TBD):
4 - q735.4
3 - q735.3
2 - q735.2
1 - q735.1
0 - q735.0
4 - ets.4
3 - ets.3
2 - ets.2
1 - ets.1
0 - ets.0
4 - wps.4
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3 - wps.3
2 - wps.2
1 - wps.1
0 - wps.0
Note that the <Admission Priority> parameter MAY be used in
combination with the <RPH Priority> parameter, which depends on the
supported QOSM. Furthermore, if more then one RPH namespace is
supported by a QOSM, then the QOSM MUST specify how the mapping
between the priorities belonging to the different RPH namespaces are
mapped to each other.
Note also that additional work is needed to communicate these flow
priority values to bearer-level network elements
[VERTICAL-INTERFACE].
7.3 QSPEC-2 Parameter Coding
7.3.1 <Token Bucket-2> Parameter [RFC2215]
A second, QSPEC-2 <Token Bucket-2> parameter is specified, as could
be needed for example to support DiffServ applications [xxxx].
Parameter Values:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 5 |r|r|r|r| 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token Bucket Rate-2 [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token Bucket Size-2 [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Data Rate-2 [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum Policed Unit-2 [m] (32-bit unsigned integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Packet Size-2 [MTU] (32-bit unsigned integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When r, b, and p terms are represented as IEEE floating point values,
the sign bit MUST be zero (all values MUST be non-negative).
Exponents less than 127 (i.e., 0) are prohibited. Exponents greater
than 162 (i.e., positive 35) are discouraged, except for specifying a
peak rate of infinity. Infinity is represented with an exponent of
all ones (255) and a sign bit and mantissa of all zeroes.
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7.3.2 <Path Latency> Parameter [RFC2210, RFC2215]
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 6 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Latency (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Path Latency is a single 32-bit integer in network byte order.
The composition rule for the <Path Latency> parameter is summation
with a clamp of (2**32 - 1) on the maximum value. The latencies are
average values reported in units of one microsecond. A system with
resolution less than one microsecond MUST set unused digits to zero.
An individual QNE can advertise a latency value between 1 and 2**28
(somewhat over two minutes) and the total latency added across all
QNEs can range as high as (2**32)-2. If the sum of the different
elements delays exceeds (2**32)-2, the end-to-end advertised delay
SHOULD be reported as indeterminate. A QNE that cannot accurately
predict the latency of packets it is processing MUST raise the
not-supported flagand either leave the value of Path Latency as is,
or add its best estimate of its lower bound. A raised not-supported
flagflag indicates the value of Path Latency is a lower bound of the
real Path Latency. The distinguished value (2**32)-1 is taken to
mean indeterminate latency because the composition function limits
the composed sum to this value, it indicates the range of the
composition calculation was exceeded.
7.3.3 <Path Jitter> Parameter
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 7 |r|r|r|r| 4 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Jitter STAT1(variance) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Jitter STAT2(99.9%-ile) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Jitter STAT3(minimum Latency) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Jitter STAT4(Reserved) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Path Jitter is a set of four 32-bit integers in network byte
order. The Path Jitter parameter is the combination of four
statistics describing the Jitter distribution with a clamp of
(2**32 - 1) on the maximum of each value. The jitter STATs are
reported in units of one microsecond. A system with resolution less
than one microsecond MUST set unused digits to zero. An individual
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QNE can advertise jitter values between 1 and 2**28 (somewhat over
two minutes) and the total jitter computed across all QNEs can range
as high as (2**32)-2. If the combination of the different element
values exceeds (2**32)-2, the end-to-end advertised jitter SHOULD be
reported as indeterminate. A QNE that cannot accurately predict the
jitter of packets it is processing MUST raise the not-supported flag
and either leave the value of Path Jitter as is, or add its best
estimate of its STAT values. A raised not-supported flag indicates
the value of Path Jitter is a lower bound of the real Path Jitter.
The distinguished value (2**32)-1 is taken to mean indeterminate
jitter. A QNE that cannot accurately predict the jitter of packets
it is processing SHOULD set its local parameter to this value.
Because the composition function limits the total to this value,
receipt of this value at a network element or application indicates
that the true path jitter is not known. This MAY happen because one
or more network elements could not supply a value, or because the
range of the composition calculation was exceeded.
NOTE: The Jitter composition function makes use of the <Path Latency>
parameter. Composition functions for loss, latency and jitter may be
found in [Y.1541].
7.3.4 <Path PLR> Parameter
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 8 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Packet Loss Ratio (32-bit floating point) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Path PLR is a single 32-bit single precision IEEE floating point
number in network byte order. The composition rule for the <Path
PLR> parameter is summation with a clamp of 10^-1 on the maximum
value. The PLRs are reported in units of 10^-11. A system with
resolution less than one microsecond MUST set unused digits to zero.
An individual QNE can advertise a PLR value between zero and 10^-2
and the total PLR added across all QNEs can range as high as 10^-1.
If the sum of the different elements values exceeds 10^-1, the
end-to-end advertised PLR SHOULD be reported as indeterminate. A QNE
that cannot accurately predict the PLR of packets it is processing
MUST raise the not-supported flag and either leave the value of Path
PLR as is, or add its best estimate of its lower bound. A raised
not-supported flag indicates the value of Path PLR is a lower bound
of the real Path PLR. The distinguished value 10^-1 is taken to mean
indeterminate PLR. A QNE which cannot accurately predict the PLR of
packets it is processing SHOULD set its local parameter to this
value. Because the composition function limits the composed sum to
this value, receipt of this value at a network element or application
indicates that the true path PLR is not known. This MAY happen
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because one or more network elements could not supply a value, or
because the range of the composition calculation was exceeded.
7.3.5 <Path PER> Parameter
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 9 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Packet Error Ratio (32-bit floating point) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Path PER is a single 32-bit single precision IEEE floating point
number in network byte order. The composition rule for the <Path
PER> parameter is summation with a clamp of 10^-1 on the maximum
value. The PERs are reported in units of 10^-11. A system with
resolution less than one microsecond MUST set unused digits to zero.
An individual QNE can advertise a PER value between zero and 10^-2
and the total PER added across all QNEs can range as high as 10^-1.
If the sum of the different elements values exceeds 10^-1, the
end-to-end advertised PER SHOULD be reported as indeterminate. A QNE
that cannot accurately predict the PER of packets it is processing
MUST raise the not-supported flag and either leave the value of Path
PER as is, or add its best estimate of its lower bound. A raised
not-supported flag indicates the value of Path PER is a lower bound
of the real Path PER. The distinguished value 10^-1 is taken to mean
indeterminate PER. A QNE which cannot accurately predict the PER of
packets it is processing SHOULD set its local parameter to this
value. Because the composition function limits the composed sum to
this value, receipt of this value at a network element or application
indicates that the true path PER is not known. This MAY happen
because one or more network elements could not supply a value, or
because the range of the composition calculation was exceeded.
7.3.6 <Ctot> <Dtot> <Csum> <Dsum> Parameters [RFC2210, RFC2212,
RFC2215]
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 10 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| End-to-end composed value for C [Ctot] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 11 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| End-to-end composed value for D [Dtot] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 12 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Since-last-reshaping point composed C [Csum] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 13 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Since-last-reshaping point composed D [Dsum] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The error term C is measured in units of bytes. An individual QNE
can advertise a C value between 1 and 2**28 (a little over 250
megabytes) and the total added over all QNEs can range as high as
(2**32)-1. Should the sum of the different QNEs delay exceed
(2**32)-1, the end-to-end error term MUST be set to (2**32)-1. The
error term D is measured in units of one microsecond. An individual
QNE can advertise a delay value between 1 and 2**28 (somewhat over
two minutes) and the total delay added over all QNEs can range as
high as (2**32)-1. Should the sum of the different QNEs delay
exceed (2**32)-1, the end-to-end delay MUST be set to (2**32)-1.
7.3.7 <Slack Term> Parameter [RFC2212, RFC2215]
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|E|N|R| 14 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Slack Term [S] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Slack term S MUST be nonnegative and is measured in microseconds.
The Slack term, S, is represented as a 32-bit integer. Its value
can range from 0 to (2**32)-1 microseconds.
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8. Security Considerations
The priority parameter raises possibilities for theft of service
attacks because users could claim an emergency priority for their
flows without real need, thereby effectively preventing serious
emergency calls to get through. Several options exist for countering
such attacks, for example
- only some user groups (e.g. the police) are authorized to set the
emergency priority bit
- any user is authorized to employ the emergency priority bit for
particular destination addresses (e.g. police)
9. IANA Considerations
This section defines the registries and initial codepoint assignments
for the QSPEC template, in accordance with BCP 26 RFC 2434 [RFC2434].
It also defines the procedural requirements to be followed by IANA in
allocating new codepoints.
This specification creates the following registries with the
structures as defined below:
Object Types (12 bits):
The following values are allocated by this specification:
0-4: assigned as specified in Section 7:
Object Type = 0: control information
= 1: QoS Desired
= 2: QoS Available
= 3: QoS Reserved
= 4: Minimum QoS
The allocation policies for further values are as follows:
5-63: Standards Action
64-127: Private/Experimental Use
128-4095: Reserved
(Note: 'Reserved' just means 'do not give these out'.)
QSPEC Version (4 bits):
The following value is allocated by this specification:
0: assigned to Version 0 QSPEC
The allocation policies for further values are as follows:
1-15: Standards Action
A specification is required to depreciate, delete, or modify QSPEC
versions.
QOSM ID (12 bits):
The allocation policies are as follows:
0-63: Specification Required
64-127: Private/Experimental Use
128-4095: Reserved
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A specification is required to depreciate, delete, or modify QOSM
IDs.
QSPEC Procedure (8 bits):
Broken down into
Message Sequence (4 bits):
The following values are allocated by this specification:
0-2: assigned as specified in Section 7.1:
Message Sequence 0:
Semantic: QSPEC Procedure = Sender-Initiated Reservations
(see Section 6.4.1)
Message Sequence 1:
Semantic: QSPEC Procedure = Receiver-Initiated Reservations
(see Section 6.4.2)
Message Sequence 2:
Semantic: QSPEC Procedure = Resource Queries (see Section 6.4.3)
The allocation policies for further values are as follows:
3-15: Standards Action
Object Combination (4 bits):
The following values are allocated by this specification:
The Object Combination field can take the values between
1 and 3 indicated in the tables in Section 6:
Message Sequence: 0
Object Combination: 1, 2, 3
Semantic: see table in Section 6.4.1
Message Sequence: 1
Object Combination: 1, 2, 3
Semantic: see table in Section 6.4.2
Message Sequence: 2
Object Combination: 1, 2, 3
Semantic: see table in Section 6.4.3
The allocation policies for further values are as follows:
3-15: Standards Action
A specification is required to depreciate, delete, or modify QSPEC
Procedures.
Error Code (16 bits)
The allocation policies are as follows:
0-127: Specification Required
128-255: Private/Experimental Use
255-65535: Reserved
A specification is required to depreciate, delete, or modify Error
Codes.
Parameter ID (12 bits):
The following values are allocated by this specification:
1-14: assigned as specified in Sections 7.2 and 7.3:
Parameter ID 1: <Excess Treatment> Parameter
2: <Traffic> Parameter
3: <QoS Class> Parameter
4: <Priority> Parameter
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5: <Token Bucket-2> Parameter
6: <Path Latency> Parameter
7: <Path Jitter> Parameter
8: <Path PLR> Parameter
9: <Path PER> Parameter
10: <Ctot> Parameter
11: <Dtot> Parameter
12: <Csum> Parameter
13: <Dsum> Parameters
14: <Slack Term> Parameter
The allocation policies for further values are as follows:
15-63: Standards Action (for QSPEC-1 parameters)
64-127: Specification Required (for QSPEC-2 parameters)
128-255: Private/Experimental Use
255-4095: Reserved
A specification is required to depreciate, delete, or modify
Parameter IDs. Note that if additional QSPEC-1 parameters are
defined in the future, this requires a standards action equivalent to
reissuing this document as a QSPEC-bis.
Excess Treatment Parameter (8 bits):
The following values are allocated by this specification:
0-3: assigned as specified in Section 7.2.1:
Excess Treatment Parameter 0: drop
1: shape
2: remark
3: no metering or policing is
permitted
The allocation policies for further values are as follows:
4-63: Standards Action
64-255: Reserved
Remark Value (8 bits)
The allocation policies are as follows:
0-63: Specification Required
64-127: Private/Experimental Use
128-255: Reserved
DSTE Class Type Sub-Parameter (8 bits):
The following values are allocated by this specification:
0-7: assigned as specified in Section 7.2.3:
DSTE Class Type Sub-Parameter 0: DSTE Class Type 0
1: DSTE Class Type 1
2: DSTE Class Type 2
3: DSTE Class Type 3
4: DSTE Class Type 4
5: DSTE Class Type 5
6: DSTE Class Type 6
7: DSTE Class Type 7
The allocation policies for further values are as follows:
8-63: Standards Action
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64-255: Reserved
Y.1541 QoS Class Sub-Parameter (8 bits):
The following values are allocated by this specification:
0-7: assigned as specified in Section 7.2.3:
Y.1541 QoS Class Sub-Parameter 0: Y.1541 QoS Class 0
1: Y.1541 QoS Class 1
2: Y.1541 QoS Class 2
3: Y.1541 QoS Class 3
4: Y.1541 QoS Class 4
5: Y.1541 QoS Class 5
6: Y.1541 QoS Class 6
7: Y.1541 QoS Class 7
The allocation policies for further values are as follows:
8-63: Standards Action
64-255: Reserved
Admission Priority Parameter (8 bits):
The following values are allocated by this specification:
0-2: assigned as specified in Section 7.2.4:
Admission Priority 0: best-effort priority flow
1: normal priority flow
2: high priority flow
255: admission priority not used
The allocation policies for further values are as follows:
3-63: Standards Action
64-254: Reserved
RPH Namespace Parameter (16 bits):
Note that [RFC4412] creates a registry for RPH Namespace and Priority
values already (see Section 12.6 of [RFC4412]). A QSPEC registry is
also created because the assigned values are being mapped to QSPEC
parameter values. The following values are allocated by this
specification:
0-5: assigned as specified in Section 7.2.4:
The allocation policies for further values are as follows:
6-63: Standards Action
64-65535: Reserved
RPH Priority Parameter (8 bits):
dsn namespace:
The allocation policies are as follows:
0-63: Standards Action
64-255: Reserved
drsn namespace:
The allocation policies are as follows:
0-63: Standards Action
64-255: Reserved
Q735 namespace:
The following values are allocated by this specification:
0-4: assigned as specified in Section 7.2.4:
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Q735 priority 4: q735.4
3: q735.3
2: q735.2
1: q735.1
0: q735.0
The allocation policies for further values are as follows:
5-63: Standards Action
64-255: Reserved
ets namespace:
The following values are allocated by this specification:
0-4: assigned as specified in Section 7.2.4:
ETS priority 4: ets.4
3: ets.3
2: ets.2
1: ets.1
0: ets.0
The allocation policies for further values are as follows:
5-63: Standards Action
64-255: Reserved
wts namespace:
The following values are allocated by this specification:
0-4: assigned as specified in Section 7.2.4:
WPS priority 4: wps.4
3: wps.3
2: wps.2
1: wps.1
0: wps.0
The allocation policies for further values are as follows:
5-63: Standards Action
64-255: Reserved
10. Acknowledgements
The authors would like to thank (in alphabetical order) David Black,
Ken Carlberg, Anna Charny, Christian Dickman, Adrian Farrel, Ruediger
Geib, Matthias Friedrich, Xiaoming Fu, Janet Gunn, Robert Hancock,
Chris Lang, Jukka Manner, An Nguyen, Dave Oran, Tom Phelan, James
Polk, Alexander Sayenko, John Rosenberg, Bernd Schloer, Hannes
Tschofenig, and Sven van den Bosch for their very helpful
suggestions.
11. Normative References
[3GPP-1] 3GPP TS 22.067 V7.0.0 (2006-03) Technical Specification, 3rd
Generation Partnership Project; Technical Specification Group
Services and System Aspects; enhanced Multi Level Precedence and
Preemption service (eMLPP) - Stage 1 (Release 7).
[3GPP-2] 3GPP TS 23.067 V7.1.0 (2006-03) Technical Specification, 3rd
Generation Partnership Project; Technical Specification Group Core
Network; enhanced Multi-Level Precedence and Preemption service
(eMLPP) - Stage 2 (Release 7).
Ash, et. al. <draft-ietf-nsis-qspec-12.txt> [Page 52]
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[3GPP-3] 3GPP TS 24.067 V6.0.0 (2004-12) Technical Specification, 3rd
Generation Partnership Project; Technical Specification Group Core
Network; enhanced Multi-Level Precedence and Preemption service
(eMLPP) - Stage 3 (Release 6).
[DSCP-REGISTRY] http://www.iana.org/assignments/dscp-registry
[PHBID-CODES-REGISTRY] http://www.iana.org/assignments/phbid-codes
[GIST] Schulzrinne, H., Hancock, R., "GIST: General Internet
Signaling Transport," work in progress.
[QoS-SIG] Manner, J., et. al., "NSLP for Quality-of-Service
Signaling," work in progress.
[RFC1832] Srinivasan, R., "XDR: External Data Representation
Standard," RFC 1832, August 1995.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 1997.
[RFC2212] Shenker, S., et. al., "Specification of Guaranteed Quality
of Service," September 1997.
[RFC2215] Shenker, S., Wroclawski, J., "General Characterization
Parameters for Integrated Service Network Elements", RFC 2215, Sept.
1997.
[RFC2475] Blake, S., et. al., "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC3140] Black, D., et. al., "Per Hop Behavior Identification
Codes," June 2001.
[RFC3181] Herzog, S., "Signaled Preemption Priority Policy Element,"
RFC 3181, October 2001.
[RFC3290] Bernet, Y., et. al., "An Informal Management Model for
Diffserv Routers," RFC 3290, May 2002.
[RFC4124] Le Faucheur, F., et. al., "Protocol Extensions for Support
of Diffserv-aware MPLS Traffic Engineering," RFC 4124, June 2005.
[RFC4412] Schulzrinne, H., Polk, J., "Communications Resource
Priority for the Session Initiation Protocol(SIP)," RFC 4412,
February 2006.
[Y.1541] ITU-T Recommendation Y.1541, "Network Performance Objectives
for IP-Based Services," May 2002.
[Y.1571] ITU-T Recommendation Y.1571, "Admission Control Priority
Levels in Next Generation Networks," July 2006.
12. Informative References
[DQOS] Cablelabs, "PacketCable Dynamic Quality of Service
Specification," CableLabs Specification PKT-SP-DQOS-I12-050812,
August 2005.
[IEEE754] Institute of Electrical and Electronics Engineers, "IEEE
Standard for Binary Floating-Point Arithmetic," ANSI/IEEE Standard
754-1985, August 1985.
[CL-QOSM] Kappler, C., "A QoS Model for Signaling IntServ
Controlled-Load Service with NSIS," work in progress.
[NETWORK-BYTE-ORDER] Wikipedia, "Endianness,"
http://en.wikipedia.org/wiki/Endianness.
Ash, et. al. <draft-ietf-nsis-qspec-12.txt> [Page 53]
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[NSIS-EXTENSIBILITY] Loughney, J., "NSIS Extensibility Model", work
in progress.
[Q.2630] ITU-T Recommendation Q.2630.3: "AAL Type 2 Signaling
Protocol - Capability Set 3" Sep. 2003
[RFC2205] Braden, B., et. al., "Resource ReSerVation Protocol (RSVP)
-- Version 1 Functional Specification," RFC 2205, September 1997.
[RFC2434] Narten, T., Alvestrand, H., "Guidelines for Writing an
IANA Considerations Section in RFCs," RFC 3181, October 1998.
[RFC2474] Nichols, K., et. al., "Definition of the Differentiated
Services Field (DS Field) in the IPv4 and IPv6 Headers," RFC 2474,
December 1998.
[RFC2597] Heinanen, J., et. al., "Assured Forwarding PHB Group," RFC
2597, June 1999.
[RFC2997] Bernet, Y., et. al., "Specification of the Null Service
Type," RFC 2997, November 2000.
[RFC3140] Black, D., et. al., "Per Hop Behavior Identification
Codes," RFC 3140, June 2001.
[RFC3393] Demichelis, C., Chimento, P., "IP Packet Delay Variation
Metric for IP Performance Metrics (IPPM), RFC 3393, November 2002.
[RFC3564] Le Faucheur, F., et. al., Requirements for Support of
Differentiated Services-aware MPLS Traffic Engineering, RFC 3564,
July 2003
[RFC3726] Brunner, M., et. al., "Requirements for Signaling
Protocols", RFC 3726, April 2004.
[RMD-QOSM] Bader, A., et. al., "RMD-QOSM - The Resource Management
in Diffserv QOS Model," work in progress.
[VERTICAL-INTERFACE] Dolly, M., Tarapore, P., Sayers, S., "Discussion
on Associating of Control Signaling Messages with Media Priority
Levels," T1S1.7 & PRQC, October 2004.
[Y.1540] ITU-T Recommendation Y.1540, "Internet Protocol Data
Communication Service - IP Packet Transfer and Availability
Performance Parameters," December 2002.
[Y.1541-QOSM] Ash, J., et. al., "Y.1541-QOSM -- Y.1541 QoS Model for
Networks Using Y.1541 QoS Classes," work in progress.
13. Authors' Addresses
Jerry Ash (Editor)
AT&T
Room MT D5-2A01
200 Laurel Avenue
Middletown, NJ 07748, USA
Phone: +1-(732)-420-4578
Fax: +1-(732)-368-8659
Email: gash@att.com
Attila Bader (Editor)
Traffic Lab
Ericsson Research
Ericsson Hungary Ltd.
Laborc u. 1 H-1037
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Budapest Hungary
Email: Attila.Bader@ericsson.com
Cornelia Kappler (Editor)
Siemens AG
Siemensdamm 62
Berlin 13627
Germany
Email: cornelia.kappler@siemens.com
Appendix A. Example of QSPEC Processing
This appendix illustrates the operation and use of the QSPEC within
the NSLP. The example configuration in shown in Figure 3.
+----------+ /-------\ /--------\ /--------\
| Laptop | | Home | | Cable | | DiffServ |
| Computer |-----| Network |-----| Network |-----| Network |----+
+----------+ | No QOSM | |DQOS QOSM | | RMD QOSM | |
\-------/ \--------/ \--------/ |
|
+-----------------------------------------------+
|
| /--------\ +----------+
| | "X"G | | Handheld |
+---| Wireless |-----| Device |
| XG QOSM | +----------+
\--------/
Figure 3: Example Configuration to Illustrate QoS-NSLP/QSPEC
Operation
In this configuration, a laptop computer and a handheld wireless
device are the endpoints for some application that has QoS
requirements. Assume initially that the two endpoints are stationary
during the application session, later we consider mobile endpoints.
For this session, the laptop computer is connected to a home network
that has no QoS support. The home network is connected to a
CableLabs-type cable access network with dynamic QoS (DQOS) support,
such as specified in the 'CMS to CMS Signaling Specification' [DQOS]
for cable access networks. That network is connected to a DiffServ
core network that uses the RMD QOSM [RMD-QOSM]. On the other side of
the DiffServ core is a wireless access network built on generation
"X" technology with QoS support as defined by generation "X". And
finally the handheld endpoint is connected to the wireless access
network.
We assume that the Laptop is the QNI and handheld device is the QNR.
The QNI will signal an initiator QSPEC object to achieve the QoS
desired on the path. As stated in Section 4, the QNI MUST support
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at least one QOSM, but it may not know the QOSM supported by the
network. In any case, if the QNI supports only one QOSM, it would
normally signal a reservation according to the requirements of that
QOSM. Furthermore, the QNI would most likely support the QOSM that
matches its functionality. For example, the default QOSM for mobile
phones might be the XG-QOSM, while the CL-QOSM might be the
default for workstations.
Referring to Figure 3, the laptop computer may choose the
CL-QOSM because it is connected to a wired network. If the
handheld device acts as the QNI, it may choose the XG-QOSM because it
is connected to the XG wireless network. On the other hand, a
particular QOSM could be configured if a user/administrator knows
that some particular QOSM is used. For example, if the laptop
computer is connected to the XG network via the XG phone, which acts
as a modem, then it reasonable to specify the XG-QOSM since resources
are accessed through the XG network,
In this example we consider two different ways to perform
sender-initiated signaling for QoS:
Case 1) The QNI sets <QoS Desired>, <QoS Available> and possibly
<Minimum QoS> QSPEC objects in the initiator QSPEC, and initializes
<QoS Available> to <QoS Desired>. Since this is a reservation in a
heterogenic network with different QOSMs supported in different
domains, each QNE on the path reads and interprets those parameters
in the initiator QSPEC that it needs to implement the QOSM within its
domain (as described below). Each QNE along the path checks to see if
<QoS Available> resources can be reserved, and if not, the QNE
reduces the respective parameter values in <QoS Available> and
reserves these values. The minimum parameter values are given in
<Minimum QoS>, if populated, otherwise zero if <Minimum QoS> is not
included. If one or more parameters in <Available QoS> fails to
satisfy the corresponding minimum values in Minimum QoS, the QNE
generates a RESPONSE message to the QNI and the reservation is
aborted. Otherwise, the QNR generates a RESPONSE to the QNI with the
<QoS Available> for the reservation.
Case 2) The QNI signals the initiator QSPEC with <QoS Desired>.
Since this is a reservation in a heterogenic network with different
QOSMs supported in different domains, each QNE on the path reads and
interprets those parameters in the initiator QSPEC that it needs to
implement the QOSM within its domain (as described below). If a QNE
cannot reserve <QoS Desired> resources, the reservation fails.
In both cases, the QNI populates QSPEC-1 and QSPEC-2 to
ensure correct treatment of its traffic in domains down the path.
Since the QNI does not know the QOSM used in downstream domains, it
includes values for those QSPEC-1 and QSPEC-2 parameters
consistent with the QOSM it is signaling and any additional
parameters it cares about. Let us assume the QNI wants to achieve
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IntServ-like QoS guarantees, and also is interested in what path
latency it can achieve. The QNI therefore includes in the QSPEC the
QOSM ID for IntServ Controlled Load Service. The QSPEC objects are
signaled with all parameters necessary for IntServ Controlled Load
and additionally the parameter to measure path latency, as follows:
<QoS Desired> = <Token Bucket>
<QoS Available> = <Token Bucket> <Path Latency>
Additionally, to ensure correct treatment further down the path, the
QNI may include <QoS Class> in <QoS Desired>.
In both cases, each QNE on the path reads and interprets those
parameters in the initiator QSPEC that it needs to implement the QOSM
within its domain. It may need additional parameters for its QOSM,
which are not specified in the initiator QSPEC. If possible, these
parameters must be inferred from those that are present, according to
rules defined in the QOSM implemented by this QNE.
There are three possibilities when a RESERVE message is received at a
QNE at a domain border (we illustrate these possibilities in the
example):
- the QNE just leaves the QSPEC as-is.
- the QNE can stack a local QSPEC on top of the initiator QSPEC (this
is new in QoS NSLP, RSVP does not do this).
- the QNE can tunnel the initiator RESERVE message through its domain
and issue its own local RESERVE message. For this new local
RESERVE message, the QNE acts as the QNI, and the QSPEC in the
domain is an initiator QSPEC. This procedure is also used by RSVP
in making aggregate reservations, in which case there is not a new
intra-domain (aggregate) RESERVE for each newly arriving
interdomain (per-flow) RESERVE, but the aggregate reservation is
updated by the border QNE (QNI) as need be. This is also how RMD
works [RMD-QOSM].
For example, at the RMD domain, a local RESERVE with its own RMD
initiator QSPEC corresponding to the RMD-QOSM is generated based on
the original initiator QSPEC according to the procedures described in
Section 4.5 of [QoS-SIG] and in [RMD-QOSM]. That is, the ingress QNE
to the RMD domain must map the QSPEC parameters contained in the
original initiator QSPEC into the RMD QSPEC. The RMD QSPEC for
example needs <Bandwidth> and <QoS Class>. <Bandwidth> is generated
from the <Token Bucket> parameter. Information on <QoS Class>,
however, is not provided. According to the rules laid out in the RMD
QOSM, the ingress QNE infers from the fact that an IntServ Controlled
Load QOSM was signaled that the EF PHB is appropriate to set the <PHB
Class> parameter. These RMD QSPEC parameters are populated in the
RMD initiator QSPEC generated within the RMD domain.
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Furthermore, the node at the egress to the RMD domain updates <QoS
Available> on behalf of the entire RMD domain if it can. If it
cannot, it raises the parameter-specific, 'not-supported' flag,
warning the QNR that the final value of these parameters in QoS
Available is imprecise.
In the XG domain, the initiator QSPEC is translated into a local
QSPEC using a similar procedure as described above. The local QSPEC
becomes the current QSPEC used within the XG domain, that is, the
it becomes the first QSPEC on the stack, and the initiator QSPEC is
second. This saves the QNEs within the XG domain the trouble of
re-translating the initiator QSPEC. At the egress edge of the XG
domain, the translated local QSPEC is popped, and the initiator QSPEC
returns to the number one position.
If the reservation was successful, eventually the RESERVE request
arrives at the QNR (otherwise the QNE at which the reservation failed
would have aborted the RESERVE and sent an error RESPONSE back to the
QNI). If the RII was included in the QoS NSLP message, the QNR
generates a positive RESPONSE with QSPEC objects <QoS Reserved> - and
for case 1 - additionally <QoS Available>. The parameters appearing
in <QoS Reserved> are the same as in <QoS Desired>, with values
copied from <QoS Available> in case 1, and with the original values
from <QoS Desired> in case 2. That is, it is not necessary to
transport the <QoS Desired> object back to the QNI since the QNI
knows what it signaled originally, and the information is not useful
for QNEs in the reverse direction. The <QoS Reserved> object should
transport all necessary information, although the <QoS Available> and
<QoS Reserved> objects may end up transporting some of the same
information.
Hence, the QNR includes the following QSPEC objects in the RESPONSE:
<QoS Reserved> = <Token Bucket>
<QoS Available> = <Token Bucket> <Path Latency>
If the handheld device on the right of Figure 3 is mobile, and moves
through different "XG" wireless networks, then the QoS might change
on the path since different XG wireless networks might support
different QOSMs. As a result, QoS NSLP/QSPEC processing will have to
renegotiate the <QoS Available> on the path. From a QSPEC
perspective, this is like a new reservation on the new section of the
path and is basically the same as any other rerouting event - to the
QNEs on the new path it looks like a new reservation. That is, in
this mobile scenario, the new segment may support a different QOSM
than the old segment, and the QNI would now signal a new reservation
(explicitly, or implicitly with the next refreshing RESERVE message)
to account for the different QOSM in the XG wireless domain. Further
details on rerouting are specified in [QoS-SIG].
Ash, et. al. <draft-ietf-nsis-qspec-12.txt> [Page 58]
Internet Draft QoS-NSLP QSPEC Template October 2006
For bit-level examples of QSPECs see the documents specifying QOSMs
[CL-QOSM, Y.1541-QOSM, RMD-QOSM].
Appendix B. Mapping of QoS Desired, QoS Available and QoS Reserved of
NSIS onto AdSpec, TSpec and RSpec of RSVP IntServ
The union of QoS Desired, QoS Available and QoS Reserved can provide
all functionality of the objects specified in RSVP IntServ, however
it is difficult to provide an exact mapping.
In RSVP, the Sender TSpec specifies the traffic an application is
going to send (e.g. token bucket). The AdSpec can collect path
characteristics (e.g. delay). Both are issued by the sender. The
receiver sends the FlowSpec which includes a Receiver TSpec
describing the resources reserved using the same parameters as the
Sender TSpec, as well as a RSpec which provides additional IntServ
QoS Model specific parameters, e.g. Rate and Slack.
The RSVP TSpec/AdSpec/RSpec seem quite tailored to receiver-initiated
signaling employed by RSVP, and the IntServ QoS Model. E.g. to the
knowledge of the authors it is not possible for the sender to specify
a desired maximum delay except implicitly and mutably by seeding the
AdSpec accordingly. Likewise, the RSpec is only meaningfully sent in
the receiver-issued RSVP RESERVE message. For this reason our
discussion at this point leads us to a slightly different mapping of
necessary functionality to objects, which should result in more
flexible signaling models.
Appendix C. Change History & Open Issues
C.1 Change History (since Version -04)
Version -05:
- fixed <QOSM hops> in Sec. 5 and 6.2 as discussed at Interim Meeting
- discarded QSPEC parameter <M> (Maximum packet size) since MTU
discovery is expected to be handled by procedure currently defined
by PMTUD WG
- added "container QSPEC parameter" in Sec. 6.1 to augment encoding
efficiency
- added the 'tunneled QSPEC parameter flag' to Sections 5 and 6
- revised Section 6.2.2 on SIP priorities
- added QSPEC procedures for "RSVP-style reservation", resource
queries and bidirectional reservations in Sec. 7.1
- reworked Section 7.2
Version -06:
- defined "not-supported flag" and "tunneled parameter flag"
(subsumes "QSPEC-2 parameter flag")
- defined "error flag" for error handling
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Internet Draft QoS-NSLP QSPEC Template October 2006
- updated bit error rate (BER) parameter to packet loss ratio (PLR)
parameter
- added packet error ratio (PER) parameter
- coding checked by independent expert
- coding updated to include RE flags in QSPEC objects and MENT flags
in QSPEC parameters
Version -07:
- added text (from David Black) on DiffServ QSPEC example in Section
6
- re-numbered QSPEC parameter IDs to start with 0 (Section 7)
- expanded IANA Considerations Section 9
Version -08:
- update to 'RSVP-style' reservation in Section 6.1.2 to mirror what
is done in RSVP
- modified text (from David Black) on DiffServ QSPEC example in
Section 6.2
- update to general QSPEC parameter formats in Section 7.1 (length
restrictions, etc.)
- re-numbered QSPEC parameter IDs in Section 7.2
- modified <Excess Treatment> parameter values in Section 7.2.2
- update to reservation priority Section 7.2.7
- specify the 3 "STATS" in the <Path Jitter> parameter, Section
7.2.9.4
- minor updates to IANA Considerations Section 9
Version -09:
- remove the DiffServ example in Section 6.2 (intent is use text as a
basis for a separate DIFFSERV-QOSM I-D)
- update wording in example in Section 4.3, to reflect use of default
QOSM and QOSM selection by QNI
- make minor changes to Section 7.2.7.2, per the exchange on the list
- add comment on error codes, after the first paragraph in Section
4.5.1
Version -10:
- rewrote Section 2.0 for clarity
- added clarifications on QSPEC-1 parameters in Section 4.2; added
discussion of forwarding options when a domain supports a different
QOSM than the QNI
- expanded Section 4.5 on error code handling, including redefined
E-Flag and editorial changes to the N-Flag and T-Flag discussions
- made some editorial clarifications in Section 4.6 on defining new
mandatory (QSPEC-1) parameters, and also reference the
[NSIS-EXTENSIBILITY] document
- Section 4.7 added to identify what a QOSM specification document
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Internet Draft QoS-NSLP QSPEC Template October 2006
must include
- clarified the requirements in Section 5.0 for defining a new QSPEC
Version
- made editorial changes to Section 6, and added procedures for
handling preemption
- removed QOSM ID assignments in Section 9.0; clarified procedures
for defining new QSPEC-1 parameters; added registry of QOSM error
codes
Version -11:
- 'QSPEC-1 parameter' replaces 'mandatory QSPEC parameter'
- 'QSPEC-2 parameter' replaces 'optional QSPEC parameter'
- R-flag ('remapped parameter flag') introduced to denote remapping,
approximating, or otherwise not strictly interpreting a QSPEC
parameter
- T-flag ('tunneled parameter flag') eliminated and incorporated
within the R-flag
- Section 4 rewritten on QOSM concept, QSPEC processing, etc. to
provide a more logical flow of information
- read-write/read-only flag associated with QSPEC objects eliminated
and object itself defined as rw or ro without a flag
- <Non QOSM Hop> parameter redefined as non-QOSM-hop Q-flag
- Section 7 on QSPEC parameter definitions revised to clearly
separate QSPEC-1 parameter coding from QSPEC-2 parameter coding
- <Traffic>, <QoS Class>, and <Priority> QSPEC-1 parameters mapped
to container parameters
- references updated to include normative references defining
procedures to 'strictly interpret' each QSPEC parameter
- Section 7.2.1 on PHB class updated to specify additional RFC 3140
cases
- Section 7.2.1 on excess treatment updated to specify excess
treatment behaviors
Version -12:
- Sections 4, 5, 6: Many editorial changes and rearrangements
- Moved example of QSPEC processing to Appendix A
- Section 7.2.2: Changed <Traffic Parameter> to fixed length
Parameter
- 3 open issues in version -11 resolved without change
C.2 Open Issues
None.
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Internet Draft QoS-NSLP QSPEC Template October 2006
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Ash, et. al. <draft-ietf-nsis-qspec-12.txt> [Page 62]
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