One document matched: draft-ietf-issll-is802-svc-mapping-02.txt
Differences from draft-ietf-issll-is802-svc-mapping-01.txt
Internet Draft M. Seaman
Expires February 1999 3Com
draft-ietf-issll-is802-svc-mapping-02.txt A. Smith
Extreme Networks
E. Crawley
Argon Networks
J. Wroclawski
MIT LCS
August 1998
Integrated Service Mappings on IEEE 802 Networks
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts.
Internet Drafts are draft documents valid for a maximum of six
months. Internet Drafts may be updated, replaced, or obsoleted by
other documents at any time. It is not appropriate to use Internet
Drafts as reference material or to cite them other than as a "working
draft" or "work in progress."
To view the entire list of current Internet-Drafts, please check the
"1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
Directories on ftp.is.co.za (Africa), ftp.nordu.net (Europe),
munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or
ftp.isi.edu (US West Coast).
This document is a product of the IS802 subgroup of the ISSLL working
group of the Internet Engineering Task Force. Comments are solicited
and should be addressed to the working group's mailing list at
issll@mercury.lcs.mit.edu and/or the authors. Copyright (C) The
Internet Society (1998). All Rights Reserved.
Abstract
This document describes mappings of IETF Integrated Services over
LANs built from IEEE 802 network segments which may be interconnected
by IEEE 802.1 MAC Bridges (switches) [1][2].
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It describes parameter mappings for supporting Controlled Load [6]
and Guaranteed Service [7] using the inherent capabilities of
relevant IEEE 802 technologies and, in particular, 802.1D-1998
queuing features in switches [2].
These mappings are one component of the Integrated Services over IEEE
802 LANs framework described in [5].
1. Introduction
The IEEE 802.1 Interworking Task Group has developed a set of
enhancements to the basic MAC Service provided in Bridged Local Area
Networks (a.k.a. "switched LANs"). As a supplement to the original
IEEE MAC Bridges standard, IEEE 802.1D-1990 [1], the updated IEEE
802.1D-1998 [2] proposes differential traffic class queuing in
switches and extends the capabilities of Ethernet/802.3 media to
carry a traffic class indicator, or "user_priority" field, within
data frames [8].
The availability of this differential traffic queuing, together with
additional mechanisms to provide admission control and signaling,
allows IEEE 802 networks to support a close approximation of the
IETF-defined Integrated Services capabilities [6][7]. This document
describes methods for mapping the service classes and parameters of
the IETF model into IEEE 802.1D network parameters. A companion
document [10] describes a signaling protocol for use with these
mappings. It is recommended that readers be familiar with the
overall framework in which these mappings and signaling protocol are
expected to be used; this framework is described fully in [5].
Within this document, Section 2 describes the method by which end
systems and routers bordering the IEEE Layer-2 cloud learn what
traffic class should be used for each data flow's packets. Section 3
describes the approach recommended to map IP-level traffic flows to
IEEE traffic classes within the Layer 2 network. Section 4 describes
the computation of Characterization Parameters by the layer 2
network. The remaining sections discuss some particular issues with
the use of the RSVP/SBM signaling protocols, and describe the
applicability of all of the above to different layer 2 network
topologies.
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2. Flow Identification and Traffic Class Selection
One model for supporting integrated services over specific link
layers treats layer-2 devices very much as a special case of routers.
In this model, switches and other devices along the data path make
packet handling decisions based on the RSVP flow and filter
specifications, and use these specifications to classify the
corresponding data packets. The specifications could either be used
directly, or could be used indirectly by mapping each RSVP session
onto a layer-2 construct such as an ATM virtual circuit.
This approach is inappropriate for use in the IEEE 802 environment.
Filtering to the per-flow level becomes expensive with increasing
switch speed; devices with such filtering capabilities are likely to
have a very similar implementation complexity to IP routers, and may
not make use of simpler mechanisms such as 802.1D user priority.
The Integrated Services over IEEE 802 LANs framework [5] and this
document use an "aggregated flow" approach based on use of layer 2
traffic classes. In this model, each arriving flow is assigned to one
of the available layer-2 classes, and traverses the 802 cloud in this
class. Traffic flows requiring similar service are grouped together
into a single class, while the system's admission control and class
selection rules ensure that the service requirements for flows in
each of the classes are met. In many situations this is a viable
intermediate point between no QoS control and full router- type
integrated services. The approach can work effectively even with
switches implementing only the simplest differential traffic
classification capability specified in the 802.1D model.
In the aggregated flow model, traffic arriving at the boundary of a
layer 2 cloud is tagged by the boundary device (end host or border
router) with an appropriate traffic class, represented as an 802.1D
"user_priority" value. Two fundamental questions are "who determines
the correspondence between IP-level traffic flows and link-level
classes?" and "how is this correspondence conveyed to the boundary
devices that must mark the data frames?"
One approach to answering these questions would be for the meanings
of the classes to be universally defined. This document would then
standardise the meanings of a set of classes; e.g. 1 = best effort, 2
= 100 ms peak delay target, 3 = 10 ms peak delay target, 4 = 1 ms
peak delay target, etc. The meanings of these universally defined
classes could then be encoded directly in end stations, and the
flow-to-class mappings computed directly in these devices.
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This universal definition approach would be simple to implement, but
is too rigid to map the wide range of possible user requirements onto
the limited number of available 802.1D classes. The model described
in [5] uses a more flexible mapping: clients ask "the network" which
user_priority traffic class to use for a given traffic flow, as
categorised by its flow-spec and layer-2 endpoints. The network
provides a value back to the requester that is appropriate
considering the current network topology, load conditions, other
admitted flows, etc. The task of configuring switches with this
mapping (e.g. through network management, a switch-switch protocol or
via some network-wide QoS-mapping directory service) is an order of
magnitude less complex than performing the same function in end
stations. Also, when new services (or other network reconfigurations)
are added to such a network, the network elements will typically be
the ones to be upgraded with new queuing algorithms etc. and can be
provided with new mappings at this time.
In this model, when a new session or "flow" requiring QoS support is
created, a client must ask "the network" which user_priority traffic
class to use for a given traffic flow, so that it can label the
packets of the flow as it places them into the network. A
request/response protocol is needed between client and network to
return this information. The request can be piggy-backed onto an
admission control request and the response can be piggy-backed onto
an admission control acknowledgment. This "one pass" assignment has
the benefit of completing the admission control transaction in a
timely way and reducing the exposure to changing conditions that
could occur if clients cached the knowledge for extensive periods. A
set of extensions to the RSVP protocol for communicating this
information have been defined[10].
The network (i.e. the first network element encountered downstream
from the client) must then answer the following questions:
1. Which of the available traffic classes would be appropriate for
this flow?
In general, a newly arriving flow might be assigned to a number
of classes. For example, if 10ms of delay is acceptable, the
flow could potentially be assigned to either a 10ms delay class
or a 1ms delay class. This packing problem is quite difficult to
solve if the target parameters of the classes are allowed to
change dynamically as flows arrive and depart. It is quite
simple if the target parameters of each class is held fixed, and
the class table is simply searched to find a class appropriate
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for the arriving flow. This document adopts the latter approach.
2. Of the appropriate traffic classes, which if any have enough
capacity available to accept the new flow?
This is the admission control problem. It is necessary to
compare the level of traffic currently assigned to each class
with the available level of network resources (bandwidth,
buffers, etc), to ensure that adding the new flow to the class
will not cause the class's performance to go below its target
values. This problem is compounded because in a priority queuing
system adding traffic to a higher-priority class can affect the
performance of lower-priority classes. The admission control
algorithm for a system using the default 802 priority behavior
must be reasonably sophisticated to provide acceptable results.
If an acceptable class is found, the network returns the chosen
user_priority value to the client.
Note that the client may be an end station, a router at the edge
of the layer 2 network, or a first switch acting as a proxy for
a device that does not participate in these protocols for
whatever reason. Note also that a device e.g. a server or router
may choose to implement both the "client" as well as the
"network" portion of this model so that it can select its own
user_priority values. Such an implementation would generally be
discouraged unless the device has a close tie-in with the
network topology and resource allocation policies. It may,
however, work acceptably in cases where there is known over-
provisioning of resources.
3. Choosing a flow's IEEE 802 user_priority class
This section describes the method by which IP-level flows are mapped
into appropriate IEEE user_priority classes. The IP-level services
considered are Best Effort, Controlled Load, and Guaranteed Service.
The major issue is that admission control requests and application
requirements are specified in terms of a multidimensional vector of
parameters e.g. bandwidth, delay, jitter, service class. This
multidimensional space must be mapped onto a set of traffic classes
whose default behaviour in L2 switches is unidimensional (i.e. strict
priority default queuing). This priority queuing alone can provide
only relative ordering between traffic classes. It can neither
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enforce an absolute (quantifiable) delay bound for a traffic class,
nor can it discriminate amongst Int-Serv flows within the aggregate
in a traffic class. Therefore, it cannot provide the absolute control
of packet loss and delay required for individual Int-Serv flows.
To provide absolute control of loss and delay three things must
occur:
(1) The amount of bandwidth available to the QoS-controlled flows
must be known, and the number of flows admitted to the network
(allowed to use the bandwidth) must be limited.
(2) A traffic scheduling mechanism is needed to give preferential
service to flows with lower delay targets.
(3) Some mechanism must ensure that best-effort flows and QoS
controlled flows that are exceeding their Tspecs do not damage
the quality of service delivered to in-Tspec QoS controlled
flows. This mechanism could be part of the traffic scheduler, or
it could be a separate policing mechanism.
For IEEE 802 networks, the first function (admission control) is
provided by a Subnet Bandwidth Manager, as discussed below. We
use the link-level user_priority mechanism at each switch and
bridge to implement the second function (preferential service to
flows with lower delay targets). Because a simple priority
scheduler cannot provide policing (function three), policing for
IEEE networks is generally implemented at the edge of the
network by a layer-3 device. When this policing is performed
only at the edges of the network it is of necessity approximate.
This issue is discussed further in [5].
3.1. Context of admission control and delay bounds
As described above, it is the combination of priority-based
scheduling and admission control that creates quantified delay
bounds. Thus, any attempt to quantify the delay bounds expected by a
given traffic class has to made in the context of the admission
control elements. Section 6 of the framework [5] provides for two
different models of admission control - centralized or distributed
Bandwidth Allocators.
It is important to note that in this approach it is the admission
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control algorithm that determines which of the Int-Serv services is
being offered. Given a set of priority classes with delay targets, a
relatively simple admission control algorithm can place flows into
classes so that the bandwidth and delay behavior experienced by each
flow corresponds to the requirements of the Controlled-Load service,
but cannot offer the higher assurance of the Guaranteed service. To
offer the Guaranteed service, the admission control algorithm must be
much more stringent in its allocation of resources, and must also
compute the C and D error terms required of this service.
A delay bound can only be realized at the admission control element
itself so any delay numbers attached to a traffic class represent the
delay that a single element can allow for. That element may
represent a whole L2 domain or just a single L2 segment.
With either admission control model, the delay bound has no scope
outside of a L2 domain. The only requirement is that it be understood
by all Bandwidth Allocators in the L2 domain and, for example, be
exported as C and D terms to L3 devices implementing the Guaranteed
Service. Thus, the end-to-end delay experienced by a flow can only be
characterized by summing along the path using the usual RSVP
mechanisms.
3.2. Default service mappings
Table 1 presents the default mapping from delay targets to IEEE 802.1
user_priority classes. However, these mappings must be viewed as
defaults, and must be changeable.
In order to simplify the task of changing mappings, this mapping
table is held by *switches* (and routers if desired) but generally
not by end-station hosts. It is a read-write table. The values
proposed below are defaults and can be overridden by management
control so long as all switches agree to some extent (the required
level of agreement requires further analysis).
In future networks this mapping table might be adjusted dynamically
and without human intervention. It is possible that some form of
network-wide lookup service could be implemented that serviced
requests from clients e.g. traffic_class = getQoSbyName("H.323
video") and notified switches of what traffic categories they were
likely to encounter and how to allocate those requests into traffic
classes. Alternatively, the network's admission control mechanisms
might directly adjust the mapping table to maximize the utilization
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of network resources. Such mechanisms are for further study.
user_priority Service
0 Default, assumed to be Best Effort
1 reserved, "less than" Best Effort
2 reserved
3 reserved
4 Delay Sensitive, no bound
5 Delay Sensitive, 100ms bound
6 Delay Sensitive, 10ms bound
7 Network Control
Table 1 - Example user_priority to service mappings
The delay bounds numbers proposed above are for per-Bandwidth
Allocator element delay targets and are derived from a subjective
analysis of the needs of typical delay-sensitive applications e.g.
voice, video. See Annex H of [2] for further discussion of the
selection of these values. Although these values appear to address
the needs of current video and voice technology, it should be noted
that there is no requirement to adhere to these values and no
dependence of IEEE 802.1 on these values.
Note: These mappings are believed to be useful defaults but further
implementation and usage experience is required. The mappings may be
refined in future editions of this document.
With this example set of mappings, delay-sensitive, admission
controlled traffic flows are mapped to user_priority values in
ascending order of their delay bound requirement. Note that the
bounds are targets only - see [5] for a discussion of the effects of
other non-conformant flows on delay bounds of other flows. Only by
applying admission control to higher-priority classes can any
promises be made to lower-priority classes.
This set of mappings also leaves several classes as reserved for
future definition.
Note: this mapping does not dictate what mechanisms or algorithms a
network element (e.g. an Ethernet switch) must perform to implement
these mappings: this is an implementation choice and does not matter
so long as the requirements for the particular service model are met.
Note: these mappings apply primarily to networks constructed from
devices that implement the priority-scheduling behavior defined as
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the default in 802.1D. Some devices may implement more complex
scheduling behaviors not based only on priority. In that circumstance
these mappings might still be used, but other, more specialized
mappings may be more appropriate.
3.3. Discussion
The recommendation of classes 4, 5 and 6 for Delay Sensitive,
Admission Controlled flows is somewhat arbitrary; any classes with
priorities greater than that assigned to Best Effort can be used.
Those proposed here have the advantage that, for transit through
802.1D switches with only two-level strict priority queuing, all
delay-sensitive traffic gets "high priority" treatment (the 802.1D
default split is 0-3 and 4-7 for a device with 2 queues).
The choice of the delay bound targets is tuned to an average expected
application mix, and might be retuned by a network manager facing a
widely different mix of user needs. The choice is potentially very
significant: wise choice can lead to a much more efficient allocation
of resources as well as greater (though still not very good)
isolation between flows.
Placing Network Control traffic at class 7 is necessary to protect
important traffic such as route updates and network management.
Unfortunately, placing this traffic higher in the user_priority
ordering causes it to have a direct effect on the ability of devices
to provide assurances to QoS controlled application traffic.
Therefore, an estimate of the amount of Network Control traffic must
be made by any device that is performing admission control (e.g.
SBMs). This would be in terms of the parameters that are normally
taken into account by the admission control algorithm. This estimate
should be used in the admission control decisions for the lower
classes (the estimate is likely to be a configuration parameter of
SBMs).
A traffic class such as class 1 for "less than best effort" might be
useful for devices that wish to dynamically "penalty tag" all of the
data of flows that are presently exceeding their allocation or Tspec.
This provides a way to isolate flows that are exceeding their service
limits from flows that are not, to avoid reducing the QoS delivered
to flows that are within their contract. Data from such tagged flows
might also be preferentially discarded by an overloaded downstream
device.
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A somewhat simpler approach would be to tag only the portion of a
flow's packets that actually exceed the Tspec at any given instant as
low priority. However, it is often considered to be a bad idea to
treat flows in this way as it will likely cause significant re-
ordering of the flow's packets, which is not desirable. Note that the
default 802.1D treatment of user_priorities 1 and 2 is "less than"
the default class 0.
4. Computation of integrated services characterization parameters by
IEEE 802 devices
The integrated service model requires that each network element that
supports integrated services compute and make available certain
"characterization parameters" describing the element's behavior.
These parameters may be either generally applicable or specific to a
particular QoS control service. These parameters may be computed by
calculation, measurement, or estimation. When a network element
cannot compute its own parameters (for example, a simple link), we
assume that the device sending onto or receiving data from the link
will compute the link's parameters as well as it's own.
The accuracy of calculation of these parameters may not be very
critical; in some cases loose estimates are all that is required to
provide a useful service. This is important in the IEEE 802 case,
where it will be virtually impossible to compute parameters
accurately for certain topologies and switch technologies. Indeed, it
is an assumption of the use of this model by relatively simple
switches (see [5] for a discussion of the different types of switch
functionality that might be expected) that they merely provide values
to describe the device and admit flows conservatively.
The discussion below presents a general outline for the computation
of these parameters, and points out some cases where the parameters
must be computed accurately. Further specification of how to export
these parameters is for further study.
4.1. General characterization parameters
There are some general parameters [9] that a device will need to use
and/or supply for all service types:
* Ingress link
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* Egress links and their MTUs, framing overheads and minimum
packet sizes (see media-specific information presented above).
* available path bandwidth: updated hop-by-hop by any device along
the path of the flow.
* minimum latency
Of these parameters, the MTU and minimum packet size information
must be reported accurately. Also, the "break bits" must be set
correctly, both the overall bit that indicates the existence of
QoS control support and the individual bits that specify support
for a particular scheduling service. The available bandwidth
should be reported as accurately as possible, but very loose
estimates are acceptable. The minimum latency parameter should
be determined and reported as accurately as possible if the
element offers Guaranteed service, but may be loosely estimated
or reported as zero if the element offers only Controlled-Load
service.
4.2. Parameters to implement Guaranteed Service
A network element supporting the Guaranteed Service must be able to
determine the following parameters [7]:
* Constant delay bound through this device (in addition to any
value provided by "minimum latency" above) and up to the
receiver at the next network element for the packets of this
flow if it were to be admitted. This includes any access
latency bound to the outgoing link as well as propagation delay
across that link. This value is advertised as the "C" parameter
of the Guaranteed Service.
* Rate-proportional delay bound through this device and up to the
receiver at the next network element for the packets of this
flow if it were to be admitted. This value is advertised as the
"D" parameter of the Guaranteed Service.
* Receive resources that would need to be associated with this
flow (e.g. buffering, bandwidth) if it were to be admitted and
not suffer packet loss if it kept within its supplied
Tspec/Rspec. These values are used by the admission control
algorithm to decide whether a new flow can be accepted by the
device.
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* Transmit resources that would need to be associated with this
flow (e.g. buffering, bandwidth, constant- and rate-proportional
delay bounds) if it were to be admitted. These values are used
by the admission control algorithm to decide whether a new flow
can be accepted by the device.
The exported characterization parameters for this service should be
reported as accurately as possible. If estimations or approximations
are used, they should err in whatever direction causes the user to
receive better performance than requested. For example, the C and D
error terms should overestimate delay, rather than underestimate it.
4.3. Parameters to implement Controlled Load
A network element implementing the Controlled Load service must be
able to determine the following [6]:
* Receive resources that would need to be associated with this
flow (e.g. buffering) if it were to be admitted. These values
are used by the admission control algorithm to decide whether a
new flow can be accepted by the device.
* Transmit resources that would need to be associated with this
flow (e.g. buffering) if it were to be admitted. These values
are used by the admission control algorithm to decide whether a
new flow can be accepted by the device.
The Controlled Load service does not export any service-specific
characterization parameters. Internal resource allocation estimates
should ensure that the service quality remains high when considering
the statistical aggregation of Controlled Load flows into 802 traffic
classes.
4.4. Parameters to implement Best Effort
For a network element that implements only best effort service there
are no explicit parameters that need to be characterized. Note that
an integrated services aware network element that implements only
best effort service will set the "break bit" described in [11].
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5. Merging of RSVP/SBM objects
Where reservations that use the SBM protocol's TCLASS object [10]
need to be merged, an algorithm needs to be defined that is
consistent with the mappings to individual user_priority values in
use in the network.
A merged reservation must receive at least as good a service as the
best of the component reservations. In the circumstances considered
here, this translates into placing the merged reservation into the
lowest delay class of those that could be used for the individual
reservations.
For the example mappings proposed in this document, the merging
device should merge to the "highest" priority value of the values
received in TCLASS objects of the PATH/RESV messages where "highest"
is defined as follows:
Lowest -------> Highest
1, 2, 0, 3, 4, 5, 6, 7
Note: this counter-intuitive ordering is an artifact of the *default*
relative treatment of user_priority values in the IEEE 802.1D
specification (see Annex H of [2]). If a device has been configured
to apply non-default treatment of user_priority values then it should
adjust this merging operation accordingly.
6. Applicability of these service mappings
Switches using layer-2-only standards (e.g. 802.1D-1990, 802.1D-
1998) need to inter-operate with routers and layer-3 switches. Wide
deployment of such 802.1D-1998 switches will occur in a number of
roles in the network: "desktop switches" provide dedicated 10/100
Mbps links to end stations and high speed core switches often act as
central campus switching points for layer-3 devices. Layer-2 devices
will have to operate in all of the following scenarios:
* every device along a network path is layer-3 capable and
intrusive into the full data stream
* only the edge devices are pure layer-2
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* every alternate device lacks layer-3 functionality
* most devices lack layer-3 functionality except for some key
control points such as router firewalls, for example.
Where int-serv flows pass through equipment which does not support
Integrated Services or 802.1D traffic management and which places all
packets through the same queuing and overload-dropping paths, it is
obvious that some of a flow's desired service parameters become more
difficult to support. In particular, the two integrated service
classes studied here, Controlled Load and Guaranteed Service, both
assume that flows will be policed and kept "insulated" from
misbehaving other flows or from best effort traffic during their
passage through the network. This cannot be done within an IEEE 802
network using devices with the default user_priority function; in
this case policing must be approximated at the network edges.
In addition, in order to provide a Guaranteed Service, *all*
switching elements along the path must participate in special
treatment for packets in such flows: where there is a "break" in
guaranteed service, all bets are off. Thus, a network path that
includes even a single switch transmitting onto a shared or half-
duplex LAN segment is unlikely to be able to provide a very good
approximation to Guaranteed Service. For Controlled Load service, the
requirements on the switches and link types are less stringent
although it is still necessary to provide differential queueing and
buffering in switches for CL flows over best effort in order to
approximate CL service. Note that users receive indication of such
breaks in the path through the "break bits" described in [11]. These
bits must be correctly set when IEEE 802 devices that cannot provide
a specific service exist in a network.
Other approaches might be to pass more information between switches
about the capabilities of their neighbours and to route around non-
QoS-capable switches: such methods are for further study. And of
course the easiest solution of all is to upgrade links and switches
to higher capacities.
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7. References
[1] "MAC Bridges", ISO/IEC 10038, ANSI/IEEE Std 802.1D-1993
[2] "Information technology - Telecommunications and information
exchange between systems - Local and metropolitan area networks
- Common specifications - Part 3: Media Access Control (MAC)
Bridges: Revision (Incorporating IEEE P802.1p: Traffic Class
Expediting and Dynamic Multicast Filtering", ISO/IEC Final CD
15802-3 IEEE P802.1D/D15, November 1997
[3] Clark, D. et al. "Integrated Services in the Internet
Architecture: an Overview" RFC1633, June 1994
[4] Braden, R., L. Zhang, S. Berson, S. Herzog, S. Jamin, "Resource
Reservation Protocol (RSVP) - Version 1 Functional
Specification", RFC 2205, September 1997
[5] Ghanwani, A., Pace, W., Srinivasan, V., Smith, A., Seaman, M.,
"A Framework for Providing Integrated Services Over Shared and
Switched LAN Technologies", Internet Draft, March 1998 <draft-
ietf-issll-is802-framework-04>
[6] Wroclawski, J., "Specification of the Controlled-Load Network
Element Service", RFC 2211, September 1997
[7] Schenker, S., Partridge, C., Guerin, R., "Specification of
Guaranteed Quality of Service", RFC 2212 September 1997
[8]
"IEEE Standards for Local and Metropolitan Area Networks: for
Virtual Bridged Local Area Networks", March 1998, IEEE Draft
Standard P802.1Q/D10
[9] Shenker, S., Wroclawski, J., "General Characterization
Parameters for Integrated Service Network Elements", RFC 2215,
September 1997
[10] Yavatkar, R., Hoffman, D., Bernet, Y., Baker, F., Speer, M.,
"SBM (Subnet Bandwidth Manager): A Protocol for Admission
Control over IEEE 802-style Networks", Internet Draft, March
1998 <draft-ietf-issll-sbm-06>
[11] Wroclawski, J., "The use of RSVP with IETF Integrated Services",
RFC 2210, September 1997.
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8. Security Considerations
Any use of QoS requires examination of security considerations
because it leaves the possibility open for denial of service or theft
of service attacks. This document introduces no new security issues
on top of those discussed in the companion ISSLL documents [5] and
[10]. Any use of these service mappings assumes that all requests
for service are authenticated appropriately.
9. Acknowledgments
This document draws heavily on the work of the ISSLL WG of the IETF
and the IEEE P802.1 Interworking Task Group.
9. Authors' Addresses
Mick Seaman
3Com Corp.
5400 Bayfront Plaza
Santa Clara CA 95052-8145
USA
+1 (408) 764 5000
mick_seaman@3com.com
Andrew Smith
Extreme Networks
10460 Bandley Drive
Cupertino CA 95014
USA
+1 (408) 863 2821
andrew@extremenetworks.com
Eric Crawley
Argon Networks
25 Porter Rd.
Littleton MA 01460
USA
+1 (978) 486 0665
esc@argon.com
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INTERNET-DRAFT Int-serv Mappings on IEEE 802 August 1998
John Wroclawski
MIT Laboratory for Computer Science
545 Technology Sq.
Cambridge, MA 02139
USA
+1 (617) 253 7885
jtw@lcs.mit.edu
Table of Contents
1 Introduction ................................................. 2
2 Flow Identification and Traffic Class Selection .............. 3
3 Choosing a flow's IEEE 802 user_priority class ............... 5
3.1 Context of admission control and delay bounds .............. 6
3.2 Default service mappings ................................... 7
3.3 Discussion ................................................. 9
4 Computation of integrated services characterization
parameters by IEEE 802 devices ............................ 10
4.1 General characterization parameters ........................ 10
4.2 Parameters to implement Guaranteed Service ................. 11
4.3 Parameters to implement Controlled Load .................... 12
4.4 Parameters to implement Best Effort ........................ 12
5 Merging of RSVP/SBM objects .................................. 13
6 Applicability of these service mappings ...................... 13
7 References ................................................... 15
8 Security Considerations ...................................... 16
9 Authors' Addresses ........................................... 16
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