One document matched: draft-baker-tsvwg-admitted-voice-dscp-01.txt
Differences from draft-baker-tsvwg-admitted-voice-dscp-00.txt
Transport Working Group F. Baker
Internet-Draft J. Polk
Updates: 4542,4594 (if approved) Cisco Systems
Intended status: Informational M. Dolly
Expires: April 2, 2007 AT&T Labs
September 29, 2006
An EF DSCP for Capacity-Admitted Traffic
draft-baker-tsvwg-admitted-voice-dscp-01
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document requests a DSCP from the IANA for a class of real-time
traffic conforming to the Expedited Forwarding Per Hop Behavior and
admitted using a CAC procedure involving authentication,
authorization, and capacity admission, as compared to a class of
real-time traffic conforming to the Expedited Forwarding Per Hop
Behavior but not subject to capacity admission or subject to very
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coarse capacity admission.
One of the reasons behind this is the need for classes of traffic
that are handled under special policies, such as the non-preemptive
Emergency Telecommunication Service, the US DoD's Assured Service
(which is similar to MLPP), or e-911. These do not need separate
DSCPs or separate PHBs that are separate from each other, but they
need a traffic class from which they can deterministically obtain
their service requirements from including SLA matters.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Problem . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Proposed Solution . . . . . . . . . . . . . . . . . . . . 6
2. Implementation of the Admitted Telephony Service Class . . . . 6
2.1. Potential implementations of EF in this model . . . . . . 6
2.2. Capacity admission control . . . . . . . . . . . . . . . . 8
2.2.1. Capacity admission control by assumption . . . . . . . 8
2.2.2. Capacity admission control by call counting . . . . . 9
2.2.3. End-point capacity admission performed by probing
the network . . . . . . . . . . . . . . . . . . . . . 9
2.2.4. Centralized capacity admission control . . . . . . . . 10
2.2.5. Distributed capacity admission control . . . . . . . . 11
2.3. Prioritized capacity admission control . . . . . . . . . . 11
3. Recommendations on implementation of an Admitted Telephony
Service Class . . . . . . . . . . . . . . . . . . . . . . . . 12
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . . 13
7.2. Informative References . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . . . . . . . 17
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1. Introduction
This document requests a DSCP from the IANA for a class of real-time
traffic conforming to the Expedited Forwarding [RFC3246][RFC3247] Per
Hop Behavior and admitted using a CAC procedure involving
authentication, authorization, and capacity admission, as compared to
a class of real-time traffic conforming to the Expedited Forwarding
Per Hop Behavior but not subject to capacity admission or subject to
very coarse capacity admission.
One of the reasons behind this is the need for classes of traffic
that are handled under special policies, such as the non-preemptive
Emergency Telecommunication Service, the US DoD's Assured Service
(which is similar to MLPP and uses preemption), or e-911, in addition
to normal routine calls that use call admission. It is possible to
use control plane protocols to generally restrict session admission
such that admitted traffic should receive the desired service, and
the policy (e.g., routine, NS/EP, e-911, etc) need not be signaled in
a DSCP. However, service providers need to distinguish between
special-policy traffic and other classes, particularly the existing
VoIP services that perform no capacity admission or only very coarse
capacity admission and can exceed their allocated resources.
This DSCP applies to the Telephony Service Class described in
[RFC4594]. WIthin an ISP and on inter-ISP links (i.e., within
networks whose internal paths are uniform at hundreds of megabits or
faster), one would expect this traffic to be carried in the Real Time
Traffic Class described in [I-D.ietf-tsvwg-diffserv-class-aggr].
1.1. Definitions
The following terms and acronyms are used in this document.
PHB: A Per-Hop-Behavior (PHB) is the externally observable
forwarding behavior applied at a DS-compliant node to a DS
behavior aggregate [RFC2475]. It may be thought of as a program
configured on the interface of an Internet host or router,
specified drop probabilities, queuing priorities or rates, and
other handling characteristics for the traffic class.
DSCP: The Differentiated Services Codepoint (DSCP), as defined in
[RFC2474], is a value which is encoded in the DS field, and which
each DS Node MUST use to select the PHB which is to be experienced
by each packet it forwards [RFC3260]. It is a 6-bit number
embedded into the 8-bit TOS field of an IPv4 datagram or the
Traffic Class field of an IPv6 datagram.
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CAC: Call Admission Control, which includes concepts of
authorization (an identified and authenticated user is determined
to also be authorized to use the service) and capacity admission
(at the present time, under some stated policy, capacity exists to
support the call). In the Internet, these are separate functions,
while in the PSTN they and call routing are carried out together.
UNI: A User/Network Interface (UNI) is the interface (often a
physical link or its virtual equivalent) that connects two
entities that do not trust each other, and in which one (the user)
purchases connectivity services from the other (the network).
Figure 1 shows two user networks connected by what appears to each
of them to be a single network ("The Internet", access to which is
provided by their service provider) which provides connectivity
services to other users.
NNI: A Network/Network Interface (NNI) is the interface (often a
physical link or its virtual equivalent) that connects two
entities that trust each other within limits, and in which the two
are seen as trading services for value. Figure 1 shows three
service networks that together provide the connectivity services
that we call "the Internet". They are different administrations
and are very probably in competition, but exchange contracts for
connectivity and capacity that enable them to offer specific
services to their customers.
Queue: There are multiple ways to build a multi-queue scheduler.
Weighted Round Robin (WRR) literally builds multiple lists and
visits them in a specified order, while a calendar queue (often
used to implement Weighted Fair Queuing,or WFQ) builds a list for
each time interval and enqueues at most a stated amount of data in
each such list for transmission during that time interval. While
these differ dramatically in implementation, the external
difference in behavior is generally negligible when they are
properly configured. Consistent with the definitions used in the
Differentiated Services Architecture [RFC2475], these are treated
as equivalent in this document, and the lists of WRR and the
classes of a calendar queue will be referred to uniformly as
"queues".
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_.--------.
,-'' `--.
,-' `-.
,-------. ,',-------. `.
,' `. ,',' `. `.
/ User \ UNI / / Service \ \
( Network +-----+ Network ) `.
\ / ; \ / :
`. ,' ; `. .+ :
'-------' / '-------' \ NNI \
; \ :
; "The Internet" \ ,-------. :
; +' `. :
UNI: User/Network Interface / Service \ |
| ( Network ) |
NNI: Network/Network Interface \ / |
: +. ,' ;
: / '-------' ;
: / ;
,-------. \ ,-------. / NNI /
,' `. : ,' `+ ;
/ User \ UNI / Service \ ;
( Network +-----+ Network ) ,'
\ / \ \ / /
`. ,' `.`. ,' ,'
'-------' `.'-------' ,'
`-. ,-'
`--. _.-'
`--------''
Figure 1: UNI and NNI interfaces
1.2. Problem
In short, the Telephony Service Class described in [RFC4594] permits
the use of capacity admission in implementing the service, but
present implementations either provide no capacity admission services
or do so in a manner that depends on specific traffic engineering.
In the context of the Internet backbone, the two are essentially
equivalent; the edge network is depending on specific engineering by
the service provider that may not be present.
However, services are being requested of the network that would
specifically make use of capacity admission, and would distinguish
among users or the uses of available Voice-on-IP capacity in various
ways. Various agencies would like to provide services as described
in section 2.6 of [RFC4504] or in [RFC4190]. This requires the use
of capacity admission to differentiate among users (which might be
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911 call centers, other offices with preferential service contracts,
or individual users gaining access with special credentials) to
provide services to them that are not afforded to routine customer-
to-customer IP telephony sessions.
1.3. Proposed Solution
The IETF is asked to differentiate, in the Telephony Service, between
sessions that are originated without capacity admission or using
traffic engineering and sessions that are originated using more
robust capacity admission procedures. Sessions of the first type use
a traffic class in which they compete without network-originated
control as described in Section 2.2.1 or Section 2.2.2, and in the
worst case lose traffic due to policing. Sessions of the second type
cooperate with network control, and may be given different levels of
preference depending on the policies that the network applies. In
order to provide this differentiation, the IETF requests that the
IANA assign a separate DSCP value to admitted sessions using the
Telephony service (see Section 4).
2. Implementation of the Admitted Telephony Service Class
2.1. Potential implementations of EF in this model
There are at least two possible ways to implement the Expedited
Forwarding PHB in this model. They are to implement separate classes
as a set of
o Multiple data plane traffic classes, each consisting of a policer
and a queue, and the queues enjoying different priorities, or
o Multiple data plane traffic classes, each consisting of a policer
but feeding into a common queue or multiple queues at the same
priority.
We will explain the difference, and describe in what way they differ
in operation. The reason this is necessary is that there is current
confusion in the industry, including a widely reported test for NS/EP
services that implemented the policing model and described it as an
implementation of the multi-priority model, and discussion in other
environments of the intermixing of voice and video traffic at
relatively low bandwidths in the policing model.
The multi-priority model is shown in Figure 2. In this model,
traffic from each service class is placed into a separate priority
queue. If data is present in both queues, traffic from one of them
will always be selected for transmission. This has the effect of
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transferring jitter from the higher priority queue to the lower
priority queue, and reordering traffic in a way that gives the higher
priority traffic a smaller average queuing delay. Each queue must
have its own policer, however, to protect the network from errors and
attacks; if a traffic class thinks it is carrying a certain data rate
but an abuse sends significantly more, the effect of simple
prioritization would not preserve the lower priorities of traffic,
which could cause routing to fail or otherwise impact an SLA.
.
policers priorities |`.
EF ---------> <=> ----------||----+ `.
high| `.
EF2---------> <=> ----------||----+ .'-----------
. medium .'
rate queues |`. +-----+ .' Priority
AF1------>||----+ `. / low |' Scheduler
| `. /
AF2------>||----+ .'-+
| .'
CS0------>||----+ .' Rate Scheduler
|' (WFQ, WRR, etc)
Figure 2: Implementation as a data plane priority
The multi-policer model is shown in Figure 3. In this model, traffic
from each service class is policed according to its SLA requirements,
and then placed into a common priority queue. Unlike the multi-
priority model, the jitter experienced by the traffic classes in this
case is the same, as there is only one queue, but the sum of the
traffic in this higher priority queue experiences less average jitter
than the elastic traffic in the lower priority.
policers priorities .
EF ---------> <=> -------\ |`.
--||----+ `.
EF2---------> <=> -------/ high| `.
. | .'--------
rate queues |`. +-----+ .'
AF1------>||----+ `. / low | .' Priority
| `. / |' Scheduler
AF2------>||----+ .'-+
| .'
CS0------>||----+ .' Rate Scheduler
|' (WFQ, WRR, etc)
Figure 3: Implementation as a data plane policer
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The difference between the two operationally is, as stated, the
issues of loss due to policing and distribution of jitter.
If the two traffic classes are, for example, voice and video,
datagrams containing video data are relatively large (generally the
size of the path MTU) while datagrams containing voice are relatively
small, on the order of only 40 to 200 bytes, depending on the codec.
On lower speed links (less than 10 MBPS), the jitter introduced by
video to voice can be disruptive, while at higher speeds the jitter
is nominal compared to the jitter requirements of voice. At access
network speeds, therefore, [RFC4594] recommends separation of video
and voice into separate queues, while at optical speeds
[I-D.ietf-tsvwg-diffserv-class-aggr] recommends that they use a
common queue.
If, on the other hand, the two traffic classes are carrying the same
type of application with the same jitter requirements, then giving
one preference in this sense does not benefit the higher priority
traffic and may harm the lower priority traffic. In such a case,
using separate policers and a common queue is a superior approach.
2.2. Capacity admission control
There are five major ways that capacity admission is done or has been
proposed to be done in Internet Voice applications:
o Capacity admission control by assumption,
o Capacity admission control by call counting,
o End-point capacity admission performed by probing the network,
o Centralized capacity admission control, and
o Distributed capacity admission control
2.2.1. Capacity admission control by assumption
The first approach is to ignore the matter entirely. If one assumes
that the capacity available to the application is uniformly far in
excess of its requirements, it is perhaps overhead that can be
ignored. This assumption is currently made in Internet VoIP
offerings such as Skype and Vonage; the end user is responsible to
place his service on a LAN connected to the Internet backbone by a
high speed broadband connection and use capable ISPs to deliver the
service. There is an authorization step in the sense that the
service ensures that the user pays his bills, but no capacity
admission is considered because there is a clear separation from the
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voice application service provider admitting the calls and the access
network provider admitting the traffic. The two have no way of
knowing about each other, except maybe in the abstract sense.
2.2.2. Capacity admission control by call counting
The H.323 gatekeeper, originally specified in 1996, operates on the
model that the considerations of Section 2.2.1 generally apply, and
that it is therefore sufficient to count calls in order to ensure
that any bottlenecks in the network are never overloaded. . Which
phone is calling which phone is configured information into the
Gatekeeper, ensuring it doesn't admit too many calls across a low
speed link. The area of influence of a Gatekeeper is called a Zone,
and limits how far away a Gatekeeper can influence calls. This is
because call counting doesn't scale when more than one server is
admitting flows across the same limited speed links. This approach
is consistent with the original design of H.323, which in 1996 was a
mechanism for connecting H.320 media gateways across a LAN. VoIP has
come a long way since then, however, and the engineering trade-offs
this approach requires in complex networks are unsatisfactory.
SIP provides the option to go down another path, to admit its servers
at layer 7, have no awareness of lower layer connectivity, resulting
in a divorce from infrastructure knowledge - save for [RFC3312],
which binds the two, but only at the endpoints.
In short, if there is a bottleneck anywhere in the network that might
be used to connect two gatekeepers, SIP proxies that do not implement
or do not configure the use of [RFC3312], or other call management
systems, the amount of traffic between the two must be contained
below that bottleneck even if the normal path is of much higher
bandwidth. In addition, the multiplexing of traffic streams between
different pairs of gatekeepers over a common LAN infrastructure is
not handled by the application, and so must be managed in the
engineering of the network.
2.2.3. End-point capacity admission performed by probing the network
[I-D.briscoe-tsvwg-cl-architecture] is one of many proposals that
have looked at probing of the network by the end system to determine
its capacity to accept a new session. Such proposals have been made
a number of times by the likes of NTT Labs, UIUC researchers, Cisco
Systems (which used its Service Assurance Architecture to probe
capacity using pings and report when network delay variability
increased), and others. Many of the proposals tested in research
have fared reasonably well in high bandwidth environments where
actual network congestion is unusual, but have not scaled down to
slower access links.
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The problem has been, in essence, that variable rate codecs can be on
the quiet side of the average for lengthy periods of time and then
become noisier. New sessions can be disrupted or disrupt existing
sessions if they perform their capacity admission procedures at a
quiet time and find themselves overrunning the allocated capacity
during a noisy time. In addition, for a service in which the network
must exercise control and differentiate among users, the users cannot
be depended on to differentiate among themselves in the network's
favor. The network must manage that service.
For this reason, [I-D.briscoe-tsvwg-cl-architecture] is only proposed
as a solution within backbone networks, leaving access networks to
provide other forms of capacity admission, and more generally such
techniques are only recommended in high bandwidth contexts. What is
not addressed, is when these quite times become not-at-all quite due
to some event occurring, leading to great amounts of traffic. A
means of maintaining existing critical calls is essential to retain a
given service. Times of disaster can be such times of extreme bursts
of the number of call attempts. Once a call is established, that
call needs to be retained.
2.2.4. Centralized capacity admission control
The concept of a Bandwidth Broker was first discussed in the research
world surrounding ESNET and Internet II in the late 1990's, and has
been discussed in the literature pertaining to the Differentiated
Services Architecture [RFC2475]. It is, in short, a central system
that performs a variety of services on behalf of clients of a network
including applying AAA services (as in [RFC2904])and authorizing them
to use specified capacity at specified times. Its strength is that
it is relatively simple, at least in concept, and can keep track of
simple book-keeping functions apart from network elements such as
routers. Its weakness is that it has no idea what the specific
routing of any stated data flow is, or its capacity apart from
services such as MPLS Traffic Engineering or engineering assumptions
specified by the designers of a network, and obtaining that
information from the network via SNMP GET or other network management
action can impose a severe network overhead, and is obviously not in
real-time.
For scaling reasons, operational Bandwidth Brokers generally take on
a semi-distributed or fully distributed nature. They are implemented
on a per-point-of-presence basis, and in satellite networks might be
implemented in each terminal. At this point, they become difficult
to operationally distinguish from distributed capacity admission
services such as described in Section 2.2.5.
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2.2.5. Distributed capacity admission control
The IETF developed the Integrated Services Model [RFC1633]and the
RSVP capacity admission protocol [RFC2205] in the early 1990's, and
then integrated it with the Differentiated Services Architecture in
[RFC2998]. Since then, the IETF has worked to describe a next
generation capacity admission protocol, which is calls NSIS, and
which is limited in scope to considering unicast sessions. [RFC4542]
looked at the issue of providing preferential services in the
Internet, and determined that RSVP with its defined extensions could
provide those services to unicast and multicast sessions.
As with the Bandwidth Broker model, there are concerns regarding
scaling, mentioned in [RFC2208]. Present implementations that have
been measured have been found to not display the scaling concerns,
however, and in any event the use of RSVP Aggregation enables the
backbone to handle such sessions in a manner similar to an ATM
Virtual Path, bundling sessions together for capacity management
purposes.
2.3. Prioritized capacity admission control
Emergency Telecommunication Service, the US DoD's Assured Service,
and e-911 each call for some form of prioritization of some calls
over others. Prioritization of the use of bandwidth is fundamentally
a matter of choices - at a point where one has multiple choices,
applying a policy that selects among them. In the PSTN, GETS
operates in favor of an authorized caller either by routing a call
that would otherwise be refused by a path unavailable to the general
public or by queuing the call until some existing call completes and
bandwidth becomes available. e-911 is similar, but the policy is
based on the called party, the emergency call center. MLPP operates
by preempting an existing call to make way for the new one.
In the Internet, routing is not performed on a per-call basis, so,
apart from interconnections to the PSTN, re-routing isn't an option.
On the other hand, in the Internet there are more classes of traffic
than in the PSTN. In the PSTN, all calls are uses of circuits, while
in the Internet some bandwidth is always reserved for elastic
applications - at least, it must be available for routing, and there
is generally significant consideration of the web, instant messaging,
and other applications. In essence, any capacity admission policy
that differentiates between calls has the option of temporarily
borrowing bandwidth from the capacity reserved for elastic traffic by
accepting new sessions under some prioritized policy while refusing
sessions of lower priority because the threshold at that priority has
been reached.
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For example, regardless of the type of capacity admission that is
used (apart from "no admission process"), one might admit prioritized
sessions using a higher bandwidth threshold than one admits lower
priority sessions.
If capacity admission as described in Section 2.2.2 is in use, the
thresholds must be set low enough that bandwidth would be available
anywhere in the network. This greatly limits the utility of such a
service due to the level of bandwidth waste that results.
If capacity admission as described in Section 2.2.3 is in use, then
either multiple thresholds must be applied in marking the traffic,
multiple traffic marks must be applied, or there must be multiple
ways to interpret the result. In any event, this is only applicable
in domains in which the law of large numbers applies.
If capacity admission as described in Section 2.2.4 is in use,
thresholds can be applied related to a general policy or SLA, or
related to the network ingress and egress in use. It requires them
to maintain state regarding network traffic routing separate from the
network; to the extent that is variable, it requires direct
monitoring in the OSS.
If capacity admission as described in Section 2.2.5 is in use,
thresholds can be applied to the critical points of the path that the
traffic in question actually takes because one is asking the
equipment that the path traverses.
3. Recommendations on implementation of an Admitted Telephony Service
Class
It is the belief of the authors that either data plane PHB described
in Section 2.1, if coupled with adequate AAA and capacity admission
procedures as described in Section 2.2.5, are sufficient to provide
the services required for an Admitted Telephony service class. If
preemption is in view, as described in section 2.3.5.2 or [RFC4542],
this provides the tools for carrying out the preemption. If
preemption is not in view, or in addition to preemptive services, the
application of different thresholds depending on call precedence has
the effect of improving the probability of call completion by
admitting preferred calls at a time that other calls are being
refused. Routine and priority traffic can be admitted using the same
DSCP value, as the choice of which calls are admitted is handled in
the admission procedure executed in the control plane, not the
policing of the data plane.
On the point of what protocols and procedures are required for
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authentication, authorization, and capacity admission, we note that
clear standards do not at this time exist for bandwidth brokers, NSIS
has not at this time been finalized and in any event is limited to
unicast sessions, and that RSVP has been standardized and has the
relevant services. We therefore recommend the use of RSVP at the
UNI. Procedures at the NNI are business matters to be discussed
between the relevant networks, and are recommended but not required.
4. IANA Considerations
This note, fundamentally, requests IANA the assign a DSCP value to a
second EF traffic class consistent with [RFC3246] and [RFC3247] and
implementing the Telephony Service Class described in [RFC4594] at
lower speeds and [I-D.ietf-tsvwg-diffserv-class-aggr] at higher
speeds. This new traffic class requires the use of capacity
admission such as RSVP services together with AAA services at the
User/Network Interface (UNI); the use of such services at the NNI is
at the option of the interconnected networks. The recommended value
for the code point 101100, paralleling the EF code point, which is
101110, and both of which are allocated from Pool 1 as described in
[RFC2474].
The code point should be referred to as EF-ADMIT.
5. Security Considerations
A major requirement of this service is effective use of a signaling
protocol such as RSVP, with the capabilities to identify its user
either as an individual or as a member of some corporate entity, and
assert a policy such as "routine" or "priority".
This capability, one has to believe, will be abused by script kiddies
and others if the proof of identity is not adequately strong or if
policies are written or implemented improperly by the carriers. This
goes without saying, but this section is here for it to be said...
6. Acknowledgements
7. References
7.1. Normative References
[I-D.ietf-tsvwg-diffserv-class-aggr]
Chan, K., "Aggregation of DiffServ Service Classes",
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draft-ietf-tsvwg-diffserv-class-aggr-00 (work in
progress), June 2006.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
December 1998.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC2998] Bernet, Y., Ford, P., Yavatkar, R., Baker, F., Zhang, L.,
Speer, M., Braden, R., Davie, B., Wroclawski, J., and E.
Felstaine, "A Framework for Integrated Services Operation
over Diffserv Networks", RFC 2998, November 2000.
[RFC3246] Davie, B., Charny, A., Bennet, J., Benson, K., Le Boudec,
J., Courtney, W., Davari, S., Firoiu, V., and D.
Stiliadis, "An Expedited Forwarding PHB (Per-Hop
Behavior)", RFC 3246, March 2002.
[RFC3247] Charny, A., Bennet, J., Benson, K., Boudec, J., Chiu, A.,
Courtney, W., Davari, S., Firoiu, V., Kalmanek, C., and K.
Ramakrishnan, "Supplemental Information for the New
Definition of the EF PHB (Expedited Forwarding Per-Hop
Behavior)", RFC 3247, March 2002.
[RFC3260] Grossman, D., "New Terminology and Clarifications for
Diffserv", RFC 3260, April 2002.
[RFC4542] Baker, F. and J. Polk, "Implementing an Emergency
Telecommunications Service (ETS) for Real-Time Services in
the Internet Protocol Suite", RFC 4542, May 2006.
7.2. Informative References
[I-D.briscoe-tsvwg-cl-architecture]
Briscoe, B., "An edge-to-edge Deployment Model for Pre-
Congestion Notification: Admission Control over a
DiffServ Region", draft-briscoe-tsvwg-cl-architecture-03
(work in progress), June 2006.
[RFC1633] Braden, B., Clark, D., and S. Shenker, "Integrated
Services in the Internet Architecture: an Overview",
RFC 1633, June 1994.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Baker, et al. Expires April 2, 2007 [Page 14]
Internet-Draft An EF DSCP for Capacity-Admitted Traffic September 2006
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC2208] Mankin, A., Baker, F., Braden, B., Bradner, S., O'Dell,
M., Romanow, A., Weinrib, A., and L. Zhang, "Resource
ReSerVation Protocol (RSVP) Version 1 Applicability
Statement Some Guidelines on Deployment", RFC 2208,
September 1997.
[RFC2904] Vollbrecht, J., Calhoun, P., Farrell, S., Gommans, L.,
Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and
D. Spence, "AAA Authorization Framework", RFC 2904,
August 2000.
[RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg,
"Integration of Resource Management and Session Initiation
Protocol (SIP)", RFC 3312, October 2002.
[RFC4190] Carlberg, K., Brown, I., and C. Beard, "Framework for
Supporting Emergency Telecommunications Service (ETS) in
IP Telephony", RFC 4190, November 2005.
[RFC4504] Sinnreich, H., Lass, S., and C. Stredicke, "SIP Telephony
Device Requirements and Configuration", RFC 4504,
May 2006.
[RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration
Guidelines for DiffServ Service Classes", RFC 4594,
August 2006.
Authors' Addresses
Fred Baker
Cisco Systems
Santa Barbara, California 93117
USA
Phone: +1-408-526-4257
Email: fred@cisco.com
Baker, et al. Expires April 2, 2007 [Page 15]
Internet-Draft An EF DSCP for Capacity-Admitted Traffic September 2006
James Polk
Cisco Systems
Richardson, Texas 75082
USA
Phone: +1-817-271-3552
Email: jmpolk@cisco.com
Martin Dolly
AT&T Labs
Middletown Township, New Jersey 07748
USA
Phone: +1-732-420-4574
Email: mdolly@att.com
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Internet-Draft An EF DSCP for Capacity-Admitted Traffic September 2006
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