One document matched: draft-polk-tsvwg-intserv-multiple-tspec-01.txt
Differences from draft-polk-tsvwg-intserv-multiple-tspec-00.txt
TSVWG WG James Polk
Internet-Draft Subha Dhesikan
Expires: January 13, 2010 Cisco Systems
Intended Status: Standards Track (PS) July 13, 2009
Updates: RFC 2205, 2210, 4495 (if published as an RFC)
Integrated Services (IntServ) Extension
to Allow Multiple TSPECs
draft-polk-tsvwg-intserv-multiple-tspec-01
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Abstract
This document defines how Integrated Services (IntServ) includes
multiple TSPECs and RSPECs in the same Resource Reservation Protocol
(RSVPv1) reservation message exchange. This ability to send multiple
TSPECs during reservation set-up helps optimize an agreeable
bandwidth through a network between endpoints in a single round
trip.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview of the Options for including multiple TSPECs and
FLOWSPECs . . . . . . . . . . . . 6
3. Overview of the Multi_TSPEC and MULTI_FLOWSPEC Solution . . . 8
3.1 New MULTI_TSPEC and MULTI-RSPEC Parameters . . . . . . . 10
3.2 Multiple TSPEC in a PATH Message . . . . . . . . . . . . 10
3.3 Multiple FLOWSPEC for Controlled Load Service . . . . . . 12
3.4 Multiple FLOWSPEC for Guaranteed Service . . . . . . . . 15
4. Rules of Usage . . . . . . . . . . . . . . . . . . . . . . . 17
4.1 Backward Compatibility . . . . . . . . . . . . . . . . . 18
4.2 Applies to Only a Single Session . . . . . . . . . . . . 18
4.3 No Special Error Handling for PATH Message . . . . . . . 18
4.4 Preference Order to be Maintained . . . . . . . . . . . 18
4.5 Bandwidth Reduction in Downstream Routers . . . . . . . 19
4.6 Merging Rules . . . . . . . . . . . . . . . . . . . . . 19
4.7 Other Considerations . . . . . . . . . . . . . . . . . . 19
5. Security considerations . . . . . . . . . . . . . . . . . . . 20
6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 20
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 21
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
9.1. Normative References . . . . . . . . . . . . . . . . . 21
9.2. Informative References . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 21
Appendix A. Option#2 Discussion . . . . . . . . . . . . . . . 22
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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document are to be interpreted as described in RFC 2119 [RFC 2119].
Calling node = PATH generator throughout this document.
Called node = RESV Generator throughout this document.
1. Introduction
This document defines how Integrated Services (IntServ) [RFC2210]
includes multiple TSPECs and multiple FLOWSPECs in the same Resource
Reservation Protocol (RSVPv1) [RFC2205] message. This ability to
send multiple TSPECs and multiple FLOWSPECs during reservation set
up helps optimize an agreeable bandwidth through a network between
endpoints in a single round trip. There is a separation of function
between the two specifications, in which RSVPv1 does not define the
internal objects to establish controlled load or guarantee services.
These are generally left to be opaque in RSVPv1. At the same time,
IntServ does not require that RSVPv1 be the only reservation
protocol for transporting both the controlled load or guaranteed
service objects - but RSVP does often carry the objects anyway.
This makes the two independent - yet related in usage, but are also
frequently talked about as if they are one and the same. They are
not.
The TSPEC - for 'traffic specification' - contains the traffic
characteristics of a sender's data flow and is a required object in
a PATH message. The TSPEC is defined in RFC 2210 and is generally
opaque to RSVP. The ADSPEC - for 'advertising specification' - is
used to gather information along the downstream data path to aid the
PATH receiver in the computation of QoS properties of this data
path. The ADSPEC is also opaque to RSVP and is defined in RFC 2210.
Both of these IntServ objects are part of the Sender Descriptor
[RFC2205].
Once the Sender Descriptor is received at its destination node,
after having traveled through the network of routers, the
SENDER_TSPEC information is matched with the information gathered in
the ADSPEC about the data path. Together, these two objects help the
receiver build its FLOWSPEC for the RESV message. The RESV message
establishes the reservation through the network of routers on the
data path established by the PATH message.
The SENDER_TSPEC is not changed in transit between endpoints (i.e.,
there are no bandwidth request adjustments along the way). However,
the ADSPEC is changed, based on the conditions experienced through
the network as the RSVP message travels hop-by-hop.
Today, real-time applications have evolved such that they are able
to dynamically adapt to available bandwidth, not only by dropping
and adding layers, but also by reducing frame rates and resolution.
Thus the current mechanism of the Integrated Services, and therefore
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RSVP, allowing the PATH generator to only provide one traffic
specification and for the resulting RESV generator to only include
one bandwidth request is limiting.
With only one SENDER_TSPEC in a PATH message and only one
FLOWSPEC in a RESV message (in Fixed Filter style of FLOWSPEC, there
are multiple FLOWSPEC but only one per filterspec), applications
will either have to accept the rejection or resort to multiple
roundtrips to get the available bandwidth when its original request
is not admitted. Since such real-time applications are
time-sensitive, participating in multiple roundtrips for
establishing bandwidth reservations is not a preferred option.
The objective of this draft is to prevent such roundtrips as well as
allow applications to successfully receive some level of bandwidth
allotment that it can use for its sessions.
While the ADSPEC provides an indication of the bandwidth available
along the path and can be used by the RESV generator in creating the
FLOWSPEC, it does not prevent failures or multiple round-trips as
described above. The intermediary routers provide a best attempt
estimate of available bandwidth in the ADSPEC object. However, it
does not take into account external policy considerations
(RFC 2215). In addition, the available bandwidth at the time of
creating the ADSPEC may not be available at the time of an actual
request in an RESV message. These reasons may cause the RESV message
to be rejected. Therefore, the ADSPEC object cannot, by itself,
satisfy the requirements of the current generations of real-time
applications.
It needs to be noted that the ADSPEC is unchanged by this new
mechanism. If ADSPEC is included in the PATH message, it is
suggested that the RESV generator use this object in determining
the FLOWSPEC.
This document creates a means for asking for more than one bandwidth
within the same RSVP reservation set-up (both PATH and RESV)
messages to optimize the determination of an agreed upon bandwidth
for this reservation. Allowing multiple TSPECs within the same PATH
message permits multiple bandwidths to be chosen from by the
RECEIVER, when the received ADSPEC is processed. This optimizes
reservation establishment. This allows the applications to
dynamically adapt their data stream to available network resources.
The concept of RSVP signaling is shown in a single direction below,
in Figure 1. Although the TSPEC is opaque to RSVP, it is shown
along with the RSVP messages for completeness. The RSVP messages
themselves need not be the focus of the reader. Instead, the
number of round trips it takes to establish a reservation is the
focus here.
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Calling node Rtr-1 Rtr-2 ... Rtr-N Called node
| | | | |
| PATH (with a TSPEC & ADSPEC) |
|------------->|--------->|----//--->|-------------->|
| | | | |
| RESV (with a FLOWSPEC) |
|<-------------|<---------|<---//----|<--------------|
| | | | |
Figure 1. Concept of RSVP in a Single Direction
Figure 1 shows a successful one-way reservation using RSVP and
IntServ.
Figure 2 shows a scenario where the RESV message, containing a
FLOWSPEC, which is generated by the Called node, after considering
both the Sender TSPEC and the ADSPEC, is rejected by an intermediary
router.
Calling node Rtr-1 Rtr-2 ... Rtr-N Called node
| | | | |
| PATH (with 1 TSPEC wanting 12Mbps) |
|------------->|--------->|----//--->|-------------->|
| | | | |
| | RESV (with 1 FLOWSPEC wanting 12Mbps) |
| | X <--//----|<--------------|
| | | | |
| ResvErr (with Admission control Error=2) |
| | |----//--->|-------------->|
| | | | |
Figure 2. Concept of RSVP Rejection due to Limited Bandwidth
The scenario above is where multiple TSPEC and multiple FLOWSPEC
optimization helps. The Calling node may support multiple bandwidths
for a given application (i.e., more than one codec for voice or
video) and therefore might want to establish a reservation with the
highest (or best) bandwidth that the network can provide for a
particular codec.
For example, bandwidths of:
12Mbps,
4Mbps, and
1.5Mbps
for the three video codecs the Calling Node supports.
This document will discuss the various options to include multiple
TSPECs and FLOWSPECs as well as the preferred option in section 2.
In section 3, the overview of the entire solution is provided. This
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section also contains the new parameters which are defined in this
document. The multiple TSPECs in a PATH message and the multiple
FLOWSPEC in a RESV message, both for controlled load and guaranteed
service are described in this section. Section 4 will cover the
rules of usage of this IntServ extension. This section contains how
this document needs to extend the scenario of when a router in the
middle of a reservation cannot accept a preferred bandwidth (i.e.,
FLOWSPEC), meaning previous routers that accepted that greater
bandwidth now have too much bandwidth reserved. This requires an
extension to RFC 4495 (RSVP Bandwidth Reduction) to cover
reservations being established, as well as existing reservations.
Section 4 also includes the merging rules.
2. Overview of the Options for Including Multiple TSPECs and FLOWSPECS
Presently, this is the format of a PATH message [RFC2205]:
<PATH Message> ::= <Common Header> [ <INTEGRITY> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
[ <POLICY_DATA> ... ]
[ <sender descriptor> ]
<sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
^^^^^^^^^^^^
[ <ADSPEC> ]
For the PATH message, the focus of this document is with what to do
with respect to the <SENDER_TSPEC> above, highlighted by the '^^^^'
characters. No other object within the PATH message will be affected
by this IntServ extension.
The ADSPEC is optional in IntServ; therefore it might or might not
be in the RSVP PATH message. Presently, the SENDER_TSPEC is limited
to one bandwidth associated with the session. This is changed in
this extension to IntServ to multiple bandwidths for the same
session. There are multiple options on how the additional bandwidths
may be added:
Option #1 - creating the ability to add one or more additional
(and complete) SENDER_TSPECs,
or
Option #2 - create the ability for the one already allowed
SENDER_TSPEC to carry more than one bandwidth amount
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for the same reservation.
or
Option #3 - create the ability for the existing SENDER_TSPEC to
remain unchanged, but add an optional <MULTI_TSPEC>
object to the <sender descriptor> such as this:
<sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
[ <ADSPEC> ] [ <MULTI_TSPEC> ]
^^^^^^^^^^^
Here is another way of looking at the option choices:
+--------------------+----------------------+---------------------+
| Option#1 | Option#2 | Option#3 |
| | | |
| +----------+ | +---------------+ | +----------+ |
| | TSPEC1 | | | MULTI_TSPEC | | | TSPEC1 | |
| +----------+ | | Object | | +----------+ |
| | | +--------+ | | |
| +----------+ | | | TSPEC1 | | | +---------------+ |
| | TSPEC2 | | | +--------+ | | | MULTI_TSPEC | |
| +----------+ | | +--------+ | | | Object | |
| | | | TSPEC2 | | | | +--------+ | |
| +----------+ | | +--------+ | | | | TSPEC2 | | |
| | TSPEC3 | | | +--------+ | | | +--------+ | |
| +----------+ | | | TSPEC3 | | | | +--------+ | |
| | | +--------+ | | | | TSPEC3 | | |
| +----------+ | | | TSPEC4 | | | | +--------+ | |
| | TSPEC4 | | | +--------+ | | | +--------+ | |
| +----------+ | +---------------+ | | | TSPEC4 | | |
| | | | +--------+ | |
| | | +---------------+ |
| | | |
+--------------------+----------------------+---------------------+
Figure 3. Concept of Option Choice
Option #1 and #2 do not allow for backward compatibility. If the
currently used SENDER_TSPEC and FLOWSPEC objects are changed, then
unless all the routers requiring RSVP processing are upgraded, this
functionality cannot be realized. As it is unlikely that all routers
along the path will have the necessary enhancements as per this
extension at one given time, therefore, it is necessary this
enhancement be made in a way that is backward compatible. Therefore,
option #1 and option #2 has been discarded in favor of option #3,
which had WG consensus in a recent IETF meeting.
Option #3: This option has the advantage of being backwards
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compatible with existing implementations of [RFC2205] and [RFC2210],
as the multiple TSPECs and FLOWSPECs are inserted as optional
objects and such objects do not need to be processed, especially if
they are not understood.
Option#3 applies to the FLOWSPEC contained in the RESV message as
well. In this option, the original SENDER_TSPEC and the FLOWSPEC are
left untouched, allowing routers not supporting this extension to be
able to process the PATH and the RESV message without issue. Two new
additional objects are defined in this document. They are the
MULTI_TSPEC and the MULTI_FLOWSPEC for the PATH and the RESV
message, respectively. The additional TSPECs (in the new MULTI_TSPEC
Object) are included in the PATH and the additional FLOWSPECS (in
the new MULTI_FLOWSPEC Object) are included in the RESV message as
new (optional) objects. These additional objects will have a class
number of 11bbbbbb, allowing older routers to ignore the object(s)
and forward each unexamined and unchanged, as defined in section
3.10 of [RFC 2205].
We state later that the top most FLOWSPEC of the new MULTI_FLOWSPEC
Object in the RESV message replaces the existing FLOWSPEC when it is
determined by the called node (perhaps along with the ADSPEC) that
the original FLOWSPEC cannot be granted. Therefore, the ordering of
preference issue is solved with Option#3 as well.
NOTE: it is important to emphasize here that including more than
one FLOWSPEC in the RESV message does not cause more than one
FLOWSPEC to be granted. This document requires that the RESV
generator arrange these multiple FLOWSPECs in the order of
preference according to the order remaining from the
MULTI_TSPECs in the PATH message. The benefit of this
arrangement is that RSVP does not have to process the rest of
the FLOWSPEC if it can admit the first one.
Additional Option #2 discussion (from the previous version of this
document) has been moved to the Appendix.
[Editor's Note: since section 2 has been expanded in
greater detail explaining each of the options and
the conclusion reached in the WG, is it necessary to
have a complete discussion on an option the WG
rejected? We are thinking not. In other words,
should the option #2 discussion be left in the
appendix, be brought in to the main part of the
document, or just deleted?]
3. Overview of the Multi_TSPEC and MULTI_FLOWSPEC Solution
This section discusses the MULTI_TSPEC and MULTI_FLOWSPEC solution.
For the Sender Descriptor within the PATH message, the original
TSPEC remains where it is, and is untouched by this IntServ
extension. What is new is the <MULTI_TSPEC> object, which is shown
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here:
<sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
[ <ADSPEC> ] [ <MULTI_TSPEC> ]
^^^^^^^^^^^
The preferred order of TSPECs sent by the PATH generator is this:
- preferred TSPEC is in the original SENDER_TSPEC
- the next in line preferred TSPEC is the first TSPEC in the
MULTI_TSPEC object
- the next in line preferred TSPEC is the second TSPEC in the
MULTI_TSPEC object
- and so on...
The FLOWSPEC composition depends upon the reservation style
requested in the RESV message. Therefore, the following shows the
inclusion of the MULTI_FLOWSPEC object with each of the styles:
WF Style:
<flow descriptor list> ::= <WF flow descriptor>
<WF flow descriptor> ::= <FLOWSPEC> [MULTI_FLOWSPEC]
FF style:
<flow descriptor list> ::=
<FLOWSPEC> <FILTER_SPEC> [MULTI_FLOWSPEC] |
<flow descriptor list> <FF flow descriptor>
<FF flow descriptor> ::=
[ <FLOWSPEC> ] <FILTER_SPEC> [MULTI_FLOWSPEC]
SE style:
<flow descriptor list> ::= <SE flow descriptor>
<SE flow descriptor> ::=
<FLOWSPEC> <filter spec list> [MULTI_FLOWSPEC]
<filter spec list> ::= <FILTER_SPEC>
| <filter spec list> <FILTER_SPEC>
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3.1 New MULTI_TSPEC and MULTI-RSPEC Parameters
This extension to Integrated Services defines two new parameter
names for <Service Number=1>. They are:
1. <parameter name> Multiple_Token_Bucket_Tspec, with a parameter
number of 125.
2. <parameter name> Multiple_Guaranteed_Service_RSpec with a
parameter name of 124
These are IANA registered in this document.
The original SENDER_TSPEC and FLOWSPEC for Controlled Service
maintain the <parameter name> of Token_Bucket_Tspec with a parameter
number of 127. The original FLOWSPEC for Guaranteed Service
maintains the <parameter name> of Guaranteed_Service_RSpec with a
parameter number of 130.
3.2 Multiple TSPEC in a PATH Message
Here is the object from [RFC2210]. It is used as a SENDER_TSPEC in a
PATH message:
31 24 23 16 15 8 7 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 | 0 (a) | reserved | 7 (b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2 | X (c) |0| reserved | 6 (d) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 | 127 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4. SENDER_TSPEC in PATH
(a) - Message format version number (0)
(b) - Overall length (7 words not including header)
(c) - Service header, service number
- '1' (Generic information) if in a PATH message;
(d) - Length of service data, 6 words not including
per-service header
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(e) - Parameter ID, parameter 127 (Token Bucket TSpec)
(f) - Parameter 127 flags (none set)
(g) - Parameter 127 length, 5 words not including per-service
header
For Option #3, Figure 4 is included in its original form for
backwards compatibility reasons, as if there were only 1 TSPEC in
the PATH. What is new when there are more than one TSPEC in
this reservation message is the new MULTI_TSPEC object in Figure 5
containing, for example, 3 (Multiple_Token_Bucket_Tspec) TSPECs in a
PATH message.
31 24 23 16 15 8 7 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 | 0 (a) | reserved | 19 (b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2 | 5 (c) |0| reserved | 18 (d) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
10 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
11 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
13 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
14 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
15 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
16 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
17 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
18 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
19 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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20 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5. MULTI_TSPEC Object
(a) - Message format version number (0)
(b) - Overall length (19 words not including header)
(c) - Service header, service number 5 (Controlled-Load)
(d) - Length of service data, 18 words not including
per-service header
(e) - Parameter ID, parameter 125 (Multiple Token Bucket TSpec)
(f) - Parameter 125 flags (none set)
(g) - Parameter 125 length, 5 words not including per-service
header
Figure 5 shows the 2nd through Nth TSPEC in the PATH in the
preferred order. The message format (a) remains the same for a
second TSPEC and for other additional TSPECs.
The Overall Length (b) includes all the TSPECs within this object,
plus the 2nd Word (containing fields (c) and (d)), which MUST NOT be
repeated. The service header fields (e),(f) and(g) are repeated for
each TSPEC.
The Service header, here service number 5 (Controlled-Load) MUST
remain the same.
Each TSPEC is six 32-bit Words long (the per-service header plus the
5 values that are 1 Word each in length), therefore the length is in
6 Word increments for each additional TSPEC. Case in point, from
the above Figure 5, Words 3-8 are the first TSPEC (2nd preferred),
Words 9-14 are the next TSPEC (3rd preferred), and Words 15-20 are
the final TSPEC (and 4th preferred) in this example of 3 TSPECs in
this MULTI_TSPEC object. There is no limit placed on the number of
TSPECs a MULTI_TSPEC object can have. However, it is RECOMMENDED to
administratively limit the number of TSPECs in the MULTI_TSPEC
object to 16 (making for a total of 17 in the PATH message).
The TSPECS are included in the order of preference by the message
generator (PATH) and MUST be maintained in that order all the way to
the Called Node. The order of TSPECs that are still grantable, in
conjunction with the ADSPEC at the Called Node, MUST retain that
order in the FLOWSPEC and MULTI_FLOWSPEC objects.
3.3 Multiple FLOWSPEC for Controlled-Load service
The format of an RSVP FLOWSPEC object requesting Controlled-Load
service is the same as the one used for the SENDER_TSPEC given in
Figure 4.
The format of the new MULTI_FLOWSPEC object is given below:
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31 24 23 16 15 8 7 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 | 0 (a) | reserved | 19 (b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2 | 5 (c) |0| reserved | 18 (d) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
10 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
11 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
13 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
14 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
15 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
16 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
17 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
18 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
19 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
20 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5. Multiple FLOWSPEC for Controlled-Load service
(a) - Message format version number (0)
(b) - Overall length (19 words not including header)
(c) - Service header, service number 5 (Controlled-Load)
(d) - Length of controlled-load data, 18 words not including
per-service header
(e) - Parameter ID, parameter 125 (Multiple Token Bucket TSpec)
(f) - Parameter 125 flags (none set)
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(g) - Parameter 125 length, 5 words not including per-service
header
This is for the 2nd through Nth TSPEC in the RESV, in the
preferred order.
The message format (a) remains the same for a second TSPEC and
for additional TSPECs.
The Overall Length (b) includes the TSPECs, plus the 2nd Word
(fields (c) and (d)), which MUST NOT be repeated. The service header
fields (e),(f) and(g), which are repeated for each TSPEC.
The Service header, here service number 5 (Controlled-Load) MUST
remain the same for the RESV message. The services, Controlled-Load
and Guaranteed MUST NOT be mixed within the same RESV message. In
other words, if one TSPEC is a Controlled Load service TSPEC, the
remaining TSPECs MUST be Controlled Load service. This same rule
also is true for Guaranteed Service - if one TSPEC is for Guaranteed
Service, the rest of the TSPECs in this PATH or RESV MUST be for
Guaranteed Service.
The Length of controlled-load data (d) also increases to account for
the additional TSPECs.
Each FLOWSPEC is six 32-bit Words long (the per-service header plus
the 5 values that are 1 Word each in length), therefore the length
is in 6 Word increments for each additional TSPEC. Case in point,
from the above Figure 5, Words 3-8 are the first TSPEC (2nd
preferred), Words 9-14 are the next TSPEC (3rd preferred), and Words
15-20 are the final TSPEC (and 4th preferred) in this example of 3
TSPECs in this FLOWSPEC. There is no limit placed on the number of
TSPECs a particular FLOWSPEC can have.
Within the MULTI_FLOWSPEC, any SENDERS_TSPEC that cannot be reserved
- based on the information gathered in the ADSPEC, is not placed in
the RESV. Otherwise, the order in which the TSPECs were in the PATH
message MUST be in the same order they are in the FLOWSPEC in the
RESV. This is the order of preference of the PATH generator, and
MUST be maintained throughout the reservation establishment, unless
the ADSPEC indicates one or more TSPECs cannot be granted, or one or
more routers along the RESV path cannot grant a particular TSPEC.
At any router that a reservation cannot honor a TSPEC, this TSPEC
MUST be removed from the RESV, or else another router along the RESV
path might reserve that TSPEC. This rule ensures this cannot
happen.
Once one TSPEC has been removed from the RESV, the next in line
TSPEC becomes the preferred TSPEC for that reservation. That router
MUST generate a ResvErr message, containing an ERROR_SPEC object
with a Policy Control Failure with Error code = 2 (Policy Control
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Failure), and an Error Value sub-code 102 (ERR_PARTIAL_PREEMPT) to
the previous routers, clearing the now over allocation of bandwidth
for this reservation. The difference between the previously
accepted TSPEC bandwidth and the currently accepted TSPEC bandwidth
is the amount this error identifies as the amount of bandwidth that
is no longer required to be reserved. The ResvErr and the RESV
messages are independent, and not normally sent by the same router.
This aspect of this document is the extension to RFC 2205 (RSVPv1).
If a RESV cannot grant the final TSPEC, normal RSVP rules apply with
regard to the transmission of a particular ResvErr.
3.4 Multiple FLOWSPEC for Guaranteed service
The FLOWSPEC object, which is used to request guaranteed service
contains a TSpec and RSpec. Here is the FLOWSPEC object from
[RFC2215] when requesting Guaranteed service:
31 24 23 16 15 8 7 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 | 0 (a) | Unused | 10 (b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2 | 2 (c) |0| reserved | 9 (d) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 | 127 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9 | 130 (h) | 0 (i) | 2 (j) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
10 | Rate [R] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
11 | Slack Term [S] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6. FLOWSPEC for Guaranteed service
(a) - Message format version number (0)
(b) - Overall length (9 words not including header)
(c) - Service header, service number 2 (Guaranteed)
(d) - Length of per-service data, 9 words not including
per-service header
(e) - Parameter ID, parameter 127 (Token Bucket TSpec)
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(f) - Parameter 127 flags (none set)
(g) - Parameter 127 length, 5 words not including parameter header
(h) - Parameter ID, parameter 130 (Guaranteed Service RSpec)
(i) - Parameter xxx flags (none set)
(j) - Parameter xxx length, 2 words not including parameter header
The difference in structure between the Controlled-Load FLOWSPEC and
Guaranteed FLOWSPEC is the RSPEC, defined in [RFC2212].
For Option #3, Figure 6 is included in its original form for
backwards compatibility reasons, as if there were only 1 FLOWSPEC in
the RESV. What is new when there is more than one TSPEC in the
FLOWSPEC in a RESV message is the new MULTI_FLOWSPEC object in
Figure 7 containing, for example, 3 FLOWSPECs requesting Guaranteed
Service.
31 24 23 16 15 8 7 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 | 0 (a) | Unused | 28 (b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2 | 2 (c) |0| reserved | 27 (d) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9 | 124 (h) | 0 (i) | 2 (j) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
10 | Rate [R] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
11 | Slack Term [S] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
13 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
14 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
15 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
16 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
17 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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18 | 124 (h) | 0 (i) | 2 (j) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
19 | Rate [R] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
20 | Slack Term [S] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
21 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
22 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
23 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
24 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
25 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
26 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
27 | 124 (h) | 0 (i) | 2 (j) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
28 | Rate [R] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
29 | Slack Term [S] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7. Multiple FLOWSPECs for Guaranteed service
(a) - Message format version number (0)
(b) - Overall length (9 words not including header)
(c) - Service header, service number 2 (Guaranteed)
(d) - Length of per-service data, 9 words not including
per-service header
(e) - Parameter ID, parameter 125 (Token Bucket TSpec)
(f) - Parameter 125 flags (none set)
(g) - Parameter 125 length, 5 words not including parameter header
(h) - Parameter ID, parameter 124 (Guaranteed Service RSpec)
(i) - Parameter 124 flags (none set)
(j) - Parameter 124 length, 2 words not including parameter header
There MUST be 1 RSPEC per TSPEC for Guaranteed Service. Therefore,
there are 5 words for Receiver TSPEC and 3 words for the RSPEC.
Therefore, for Guaranteed Service, the TSPEC/RSPEC combination
occurs in increments of 8 words.
4. Rules of Usage
The following rules apply to nodes adhering to this specification:
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4.1 Backward Compatibility
If the recipient does not understand this extension, it ignores this
MULTI_TSPEC object, and operates normally for a node receiving this
RSVP message.
4.2 Applies to Only a Single Session
When there is more than one TSPEC object or more than one FLOWSPEC
object, this MUST NOT be considered for more than one flow created.
These are OR choices for the same flow of data. In order to attain
three reservations between two endpoints, three different
reservation requests are required, not one reservation request with
3 TSPECs.
4.3 No Special Error Handling for PATH Message
If a problem occurs with the PATH message - regardless of this
extension, normal RSVP procedures apply (i.e., there is no new
PathErr code created within this extension document) - resulting in
a PathErr message being sent upstream towards the PATH originator,
as usual.
4.4 Preference Order to be Maintained
When more than one TSPEC is in a PATH message, the order of TSPECs
is decided by the Calling Node and MUST be maintained within the
SENDER_TSPEC. The same order MUST be carried to the FLOWSPECs by the
RESV Generator. No additional TSPECS can be introduced by the Resv
generator or the router processing these new objects. The deletion
of TSPECs from a PATH message is not permitted. The deletion of the
TSPECs when forming the FLOWSPEC is allowed by the Resv generator in
the following cases:
- If one or more preferred TSPECs cannot be granted by a router as
discovered during processing of the ADSPEC by the RESV Generator,
then they can be omitted when adding the TSPECs to the FLOWSPEC.
- If one or more TSPECs arriving in the PATH message at the Called
Node is not preferred by the Resv Generator, then it MAY omit them
while creating the FLOWSPEC.
The deletion of the TSPECs in the router during the processing of
this MULTI_FLOWSPEC object is allowed in the following cases:
- If the original FLOWSPEC cannot be granted by a router then the
router may discard that FLOWSPEC and replace it with the topmost
FLOWSPEC from the MULTI_FLOWSPEC project. This will cause the
topmost FLOWSPEC in the MULTI_FLOWSPEC object to be removed. The
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next FLOWSPECs becomes the topmost FLOWSPEC.
The preferred order of the remaining TSPECs MUST be kept intact both
the Resv Generator as well as the router processing these objects.
4.5 Bandwidth Reduction in Downstream Routers
If there are multiple FLOWSPECs in a single RESV message, it is
quite possible that a higher bandwidth is reserved at a previous
downstream device. Thus, any device that grants a reservation that
is not the highest will have to inform the previous downstream
routers to reduce the bandwidth reserved for this particular
session.
The bandwidth reduction RFC [RFC4495] has the ability to partially
preempt existing reservations. However, it does not address the need
that this draft addresses. RFC 4495 defines an ability to preempt
part of an existing reservation so as to admit a new incoming
reservation with a higher priority, in lieu of tearing down the
whole reservation with lower priority. It does not specify the
capability to reduce the bandwidth a RESV set up along the data path
before the reservation is realized (from source to destination),
when a subsequent router cannot support a more preferred FLOWSPEC
contained in that RESV. This document will extend the RFC 4495
defined error to work for previous hops while a reservation is being
established.
4.6 Merging Rules
RFC 2205 defines the rules for merging two FLOWSPECs into a single
FLOWSPEC. In the case of MULTI_FLOWSPECs, merging of the two or more
MULTI-FLOWSPEC must be done to arrive at a single MULTI_FLOWSPEC.
The merged MULTI_FLOWSPEC will contain all the flow specification
components of the individual MULTI_FLOWSPECs in descending orders of
bandwidth. If two FLOWSPECs have the same bandwidth, then they are
to be merged into one FLOWSPEC using the rules defined in RFC 2205.
The resultant FLOWSPEC is added to the MULTI_FLOWSPEC based on its
bandwidth in descending orders of bandwidth.
As a result of such merging, the number of FLOWSPECs in a
MULTI_FLOWSPEC object should be the sum of the number of FLOWSPECs
from individual MULTI_FLOWSPEC that have been merged. For each
duplicate, the number of FLOWSPEC will be reduced by one.
4.7 Other Considerations
- RFC 4495 articulates why a ResvErr is more appropriate to use for
reducing the bandwidth of an existing reservation, vs. a ResvTear.
- Refreshes only include the TSPECs that were accepted. One SHOULD
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be sent immediately upon the Calling node receiving the RESV, to
ensure all routers in this flow are synchronized with which TSPEC
is in place.
- Periodically, it might be appropriate to attempt to increase the
bandwidth of an accepted reservation with one of the TSPECs that
were not accepted by the network when the reservation was first
installed. This SHOULD NOT occur too regularly. This document
currently offers no guidance on the frequency of this bump request
for a rejected TSPEC from the PATH.
5. Security considerations
The security considerations for this document do not exceed what is
already in RFC 2205 (RESV) or RFC 2210 (IntServ), as nothing in
either of those documents prevent a node from requesting a lot of
bandwidth in a single TSPEC. This document merely reduces the
signaling traffic load on the network by allowing many requests that
fall under the same policy controls to be included in a single
round-trip message exchange.
Further, this document does not increase the security risk(s) to
that defined in RFC 4495, where this document creates additional
meaning to the RFC 4495 created error code 102.
A misbehaving Calling Node can include too many TSPECs in the
MULTI_TSPEC object, which can lead to an amplification attack. That
said, a bad implementation can create a reservation for each TSPEC
received from within the Resv message. The number of TSPECs in the
new MULTI_TSPEC object is limited, and the spec clearly states that
only a single reservation is to be set up per Resv message.
6. IANA considerations
This document IANA registers the following new parameter name in the
Integ-serv assignments at [IANA]:
Registry Name: Parameter Names
Registry:
Value Description Reference
-------- -------------------------------------------- ---------
125 Multiple_Token_Bucket_Tspec [RFCXXXX]
124 Multiple_Guaranteed_Service_RSpec [RFCXXXX]
Where RFCXXXX is replaced with the RFC number assigned to this
Document.
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7. Acknowledgments
The authors wish to thank Francois Le Faucheur, Fred Baker, Joe
Touch, Bruce Davie, Dave Oran, Ashok Narayanan, Lou Berger, Lars
Eggert and Janet Gunn for their helpful comments and guidance in
this effort.
8. References
8.1. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997
[RFC2205] R. Braden, Ed., L. Zhang, S. Berson, S. Herzog, S. Jamin,
"Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997
[RFC2210] J. Wroclawski, "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 1997
[RFC2212] S. Shenker, C. Partridge, R. Guerin, "Specification of
Guaranteed Quality of Service", RFC 2212, September 1997
[RFC2215] S. Shenker, J. Wroclawski, "General Characterization
Parameters for Integrated Service Network Elements",
RFC 2212, September 1997
[RFC4495] J. Polk, S. Dhesikan, "A Resource Reservation Protocol
(RSVP) Extension for the Reduction of Bandwidth of a
Reservation Flow", RFC 4495, May 2006
8.2. Informative References
[IANA] http://www.iana.org/assignments/integ-serv
Authors' Addresses
James Polk
3913 Treemont Circle
Colleyville, Texas, USA
+1.817.271.3552
mailto: jmpolk@cisco.com
Subha Dhesikan
Cisco Systems
170 W. Tasman Drive
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San Jose, CA 95134 USA
mailto: sdhesika@cisco.com
Appendix A: Multiple Sender and Receiver in Single TSPEC Modification
Appendix A here discusses our solution from an Option #2 perspective
(i.e., this appendix assumes there is a single group of TSPEC
object, with multiple TSPECs within that object - for both
SENDER_TSPECs (in a PATH) and RECEIVER_TSPECs (in a RESV)). See
Section 3 for the Option #3 discussion of our solution involving
more than one TSPEC object (i.e., the original TSPEC as defined in
[RFC2210] plus the new MULTI_TSPEC object defined here).
These TSPEC parameters are used by data senders to describe the
traffic parameters of traffic it expects to generate, and by QoS
control services to describe the parameters of traffic for which the
reservation should apply [RFC 2215]. This appendix specifies the
detailed contents and wire format of a TSPEC that has been modified
to allow multiple bandwidths, hence the term "Multiple TSPECs".
A.1 New Multiple_Token_Bucket_Tspec Parameter in TSPEC
This extension to Integrated Services allows <Service Number=1> to
use a new <parameter name>. This document creates the new
<parameter names> Multiple_Token_Bucket_Tspec, with a parameter
number of 125. This is IANA registered in this document. It is the
combination of the two that indicates the type of object is
proposed for this data flow, which is consistent with the rules
established in [RF2210].
When there is more than one TSPEC, this MUST NOT be
considered for more than one flow. These are OR choices for the
same flow of data. In order to attain 3 reservations between two
endpoints, 3 different reservation requests are required, not one
reservation request with 3 TSPECs. This optimization, for example
in a RESV FLOWSPEC, is to attain the available bandwidth in a single
request, instead of
a request-fail, (time wasted)
another request-fail, (more time wasted)
then finally
a request-succeed.
The above multiple roundtrips take longer than it needs to, and the
purpose of this document is how to make this situation go away (for
compliant nodes).
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A.2 SENDER_TSPEC and FLOWSPEC for Controlled-Load service
Here is the object from [RFC2210]. It is used as a SENDER_TSPEC and
as a RECEIVER_TSPEC (with one exception) requesting Controlled-Load
service with different Service Headers:
31 24 23 16 15 8 7 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 | 0 (a) | reserved | 7 (b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2 | X (c) |0| reserved | 6 (d) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 | 127 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure A1. TSPEC (in SENDER_TSPEC in PATH and RECEIVER_TSPEC in
RESV)
(a) - Message format version number (0)
(b) - Overall length (7 words not including header)
(c) - Service header, service number
- '1' (Generic information) if in a PATH message;
- '5' (Controlled-Load) if in a RESV message
(d) - Length of service data, 6 words not including
per-service header
(e) - Parameter ID, parameter 127 (Token Bucket TSPEC)
(f) - Parameter 127 flags (none set)
(g) - Parameter 127 length, 5 words not including per-service
header
Again, based on Option #2 - here is the new TSPEC object containing,
for example, 3 (Multiple Token Bucket TSPEC) TSPECs when requesting
Controlled-Load service. This is based on option #2 mentioned above.
The SENDER_TSPEC with a Multiple_Token_Bucket_Tspec will differ in
only one respect when this is inserted into the FLOWSPEC of the
RESV. That difference is in the service number field (c), in which
the SENDER_TSPEC has a '1', the FLOWSPEC has a '5' - indicating
Controlled Load service. Both will have the new Parameter ID of
125, which is IANA registered with this document.
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31 24 23 16 15 8 7 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 | 0 (a) | reserved | 19 (b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2 | 5 (c) |0| reserved | 18 (d) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
10 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
11 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
13 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
14 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
15 | 125 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
16 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
17 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
18 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
19 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
20 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure A2. Multiple TSPECs for Controlled-Load service
(a) - Message format version number (0)
(b) - Overall length (19 words not including header)
(c) - Service header, service number 5 (Controlled-Load)
(d) - Length of controlled-load data, 18 words not including
per-service header
(e) - Parameter ID, parameter 125 (Multiple Token Bucket TSPEC)
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(f) - Parameter 125 flags (none set)
(g) - Parameter 125 length, 5 words not including per-service
header
The message format (a) remains the same for one TSPEC and
multiple TSPECs.
The Overall Length (b) increases to include the additional
TSPECs only, plus the 2nd and 3rd Words - which also MUST NOT
be repeated, which includes fields (c) and (d), and (e), (f) and
(g), respectively.
The Service header, here service number 5 (Controlled-Load) MUST
remain the same. The services, Controlled-Load and Guaranteed MUST
NOT be mixed within the same RESV message. In other words,
if one TSPEC is a Controlled Load service TSPEC, the remaining
TSPECs MUST be Controlled Load service. This same rule also is true
for Guaranteed Service - if one TSPEC is for Guaranteed Service, the
rest of the TSPECs in this PATH or RESV MUST be for Guaranteed
Service.
The Length of controlled-load data (d) also increases to account for
the additional TSPECs.
Each TSPEC is six 32-bit Words long (the per-service header plus the
5 values that are 1 Word each in length), therefore the length is in
6 Word increments for each additional TSPEC. Case in point, from
the above Figure 5, Words 3-8 are the first TSPEC, Words 9-14 are
the next TSPEC, and Words 15-20 are the final TSPEC in this example
of 3 TSPECs in this FLOWSPEC. There is no limit placed on the
number of TSPECs a particular FLOWSPEC can have.
The TSPECS are included in the order of preference by the message
generator (PATH and RESV) and MUST be maintained in that order.
Within the Sender_Descriptor, any TSPEC that cannot be reserved -
based on the information gathered in the ADSPEC, is not placed in
the RESV. Otherwise, the order in which the TSPECs were in the PATH
message MUST be in the same order they are in the FLOWSPEC in the
RESV. This is the order of preference of the PATH generator, and
MUST be maintained throughout the reservation establishment, unless
the ADSPEC indicates one or more TSPECs cannot be granted, or one
or more routers along the RESV path cannot grant a particular
TSPEC. The ADSPEC directly affects which TSPEC(s) are placed in the
RESV. At any router that a reservation cannot honor a TSPEC, this
TSPEC MUST be removed from the RESV, or else another router along
the RESV path might reserve that TSPEC. This rule ensures this
cannot happen.
Once one TSPEC has been removed from the RESV, the next in line
TSPEC becomes the preferred TSPEC for that reservation. That router
MUST generate a ResvErr message, containing an ERROR_SPEC object
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with a Policy Control Failure with Error code = 2 (Policy Control
Failure), and an Error Value sub-code 102 (ERR_PARTIAL_PREEMPT) to
the previous routers, clearing the now over allocation of bandwidth
for this reservation. The difference between the previously
accepted TSPEC bandwidth and the currently accepted TSPEC bandwidth
is the amount this error identifies as the amount of bandwidth that
is no longer required to be reserved. The ResvErr and the RESV
messages are independent, and not normally sent by the same router.
This aspect of this document is the extension to RFC 2205 (RSVPv1).
If a RESV cannot grant the final TSPEC, normal RSVP rules apply with
regard to the transmission of a particular ResvErr.
A.3 FLOWSPEC for Guaranteed service
Here is the FLOWSPEC object from [RFC2215] when requesting
Guaranteed service:
31 24 23 16 15 8 7 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1 | 0 (a) | Unused | 10 (b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2 | 2 (c) |0| reserved | 9 (d) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 | 127 (e) | 0 (f) | 5 (g) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Token Bucket Rate [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5 | Token Bucket Size [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 | Peak Data Rate [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7 | Minimum Policed Unit [m] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Maximum Packet Size [M] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9 | 130 (h) | 0 (i) | 2 (j) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
10 | Rate [R] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
11 | Slack Term [S] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure A3. Multiple TSPECs for Guaranteed service
(a) - Message format version number (0)
(b) - Overall length (9 words not including header)
(c) - Service header, service number 2 (Guaranteed)
(d) - Length of per-service data, 9 words not including
per-service header
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(e) - Parameter ID, parameter 127 (Token Bucket TSpec)
(f) - Parameter 127 flags (none set)
(g) - Parameter 127 length, 5 words not including parameter header
(h) - Parameter ID, parameter 130 (Guaranteed Service RSpec)
(i) - Parameter 130 flags (none set)
(j) - Parameter 130 length, 2 words not including parameter header
The difference in structure between the Controlled-Load FLOWSPEC and
Guaranteed FLOWSPEC is the RSPEC, defined in [RFC2212].
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