TSVWG R. Geib, Ed.
Internet-Draft Deutsche Telekom
Intended status: Informational October 18, 2013
Expires: April 21, 2014
DiffServ interconnection classes and practice
draft-geib-tsvwg-diffserv-intercon-04
Abstract
This document proposes a limited set of interconnection QoS PHBs and
PHB groups. It further introduces some DiffServ deployment aspects.
The proposals made here should be integrated into a revised version
of RFC5127.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 21, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Aggregating PHBs of a class by a DSCP Precedence Prefix . . . 5
4. An Interconnection class and codepoint scheme . . . . . . . . 6
5. Consolidation of QoS standards by the interconnection
codepoint scheme . . . . . . . . . . . . . . . . . . . . . . . 7
6. Treatment of Network Control traffic at carrier
interconnection interfaces . . . . . . . . . . . . . . . . . . 9
7. MPLS, Ethernet and DSCP Precedence Prefixes for aggregated
classes . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8. QoS class name selection . . . . . . . . . . . . . . . . . . . 11
9. Allow for DiffServ extendibility on MPLS and Ethernet level . 12
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
12. Security Considerations . . . . . . . . . . . . . . . . . . . 12
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
13.1. Normative References . . . . . . . . . . . . . . . . . . . 12
13.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. Change log . . . . . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
This draft proposes a DiffServ interconnection class and codepoint
scheme. At least one party of an interconnection often is a network
provider. Many network providers operate Aggregated DiffServ
classes. This draft contains concepts and current practice relevant
for a revised version of RFC5127 [RFC5127]. Its main purpose is to
be considered as an input for the latter task.
DiffServ sees deployment in many networks for the time being. As
described in the introduction of the draft DiffServ problem statement
[I-D.polk-tsvwg-diffserv-stds-problem-statement], remarking of
packets at domain boundaries is a DiffServ feature. This draft
proposes a set of standard QoS classes and codepoints at
interconnection points to which and from which locally used classes
and codepoints should be mapped. Such a scheme simplifies
interconnection negotiations and ensures that end to end class
properties remain roughly the same while codepoints may change.
The proposed Interconnection class and codepoint scheme tries to
reflect and consolidate related DiffServ and QoS standardisation
efforts outside of the IETF, namely MEF, GSMA and ITU.
IP Precedence has been deprecated when DiffServ was standardised. It
is common practice today however to copy the DSCPs Bits 0-2 (called
DSCP Precedence Prefix in the following) into MPLS TC or Ethernet
P-Bits. This is also reflected by the DiffServ codepoint definitions
of AF and EF. Class based PHBs may be applied in core network
sections rather than then DSCP based PHBs.
The set of available router and traffic management tools to configure
and operate DiffServ classes is limited. This should be reflected by
class definitions. These may in the end be more related to transport
properties than to application requirements. Please interpret
transport properties as "congestion aware" and "not congestion aware"
rather then TCP or UDP.
Finally, this draft proposes to leave some lass Selector Codepoint
and by that MPLS TC codepoint space to allow for future DiffServ
extensions like ECN/PCN and domain internal classes. An example for
an internal PHB may be CS6. Some operators protect their network
internal routing and / or management traffic by CS6. This PHB is
possibly not available to transport customer or interconnection
partner signaling and management traffic.
In addition to the standardisation activities which triggered this
work, other authors published RFCs or drafts which may benefit from
an interconnection class- and codepoint scheme. RFC 5160 suggests
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Meta-QoS-Classes to enable deployment of standardised end to end QoS
classes [RFC5160]. The authors agree that the proposed
interconnection class- and codepoint scheme as well as the idea of
standardised end to end classes would complement their own work.
Work on signaling Class of Service at interconnection interfaces by
BGP [I-D.knoll-idr-cos-interconnect], [ID.idr-sla] is beyond the
scope of this draft. Should the basic transport and class properties
be standardised as proposed here, signaled access to QoS classes may
be of interest. The current BGP drafts focus on exchanging SLA and
traffic conditioning parameters. They seem to assume that common
interpretation of the PHB properties identified by DSCPs has been
established prior to exchanging further details by BGP signaling.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Terminology
This draft re-uses existing terminology.
DSCP Precedence Prefix The bits 0-2 of the DSCP (marked "x" in this
generic DSCP field: xxxddd) are called the DSCP Precedence
Prefix [RFC2474] in the following. By ignoring the value of
bits 3-6 ( d stands for don' care), a simple aggregation of
PHBs differed by DSCP is possible in IP and MPLS backbones,
but also if Ethernet transport is applied. This is discussed
in more detail below.
Class A class is a set of one or more PHBs utilising the same PHB
if classified by a single identical DSCP Precedence Prefix
(e.g. an AF class [RFC2597]). It is a PHB Scheduling Class
[RFC3260] or an Ordered Aggregate. A class is a PHB group
[RFC2575]. Different classes must not be aggregated.
PHB On IP layer, a single DSCP identifies a single PHB. In
addition, this document proposes an MPLS like classification
of traffic for a single PHB based on the DSCP Precedence
Prefix (see [RFC3270]).
The above references may be incomplete and mostly refer to the early
DiffServ RFCs only.
To gain clarity, "DSCP based PHB selection" is only meant if
expressed exactly that way in the remaining document. "PHB" here
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relates to DSCP Precedence Prefix based PHB selection.
The following current practice issues relate to the concept of the
DiffServ interconnection class proposal rather than to terminology.
They serve as additional motivation of this activity:
o Abstract class names like "EF" are preferential over those being
close to an application, like "Voice". Unfortunately, non QoS
experts can't handle abstract class names. Hence and usually
sooner than later, classes are named for applications or groups of
them. One consequence however is, that people tend to combine
application group class names and SLA parameters. Based on an
application specific name and some worst case performance numbers
on a paper, they often decide that their application needs a
separate new QoS class.
o Worse than that, but very present in practice, is the class
abstraction level which is preferred by those dealing with QoS (as
experts or non experts): the DSCPs or the DSCP Precedence Prefix
values. These are the commodity abstractions applied for QoS
classes. Most of these persons have fixed class to codepoint
mappings in their minds, which they can't easily adapt on per
customer or per interconnection partner basis.
While these issues aren't to be solved by IETF (QoS experts could and
should of course teach staff to use proper Diffserv terminology and
concepts), a simple and comprehensible QoS interconnection class
scheme also is helpful in this area.
3. Aggregating PHBs of a class by a DSCP Precedence Prefix
Operation of IP and MPLS networks and router configuration is
simplified, if DSCP based PHBs can be aggregated into a single class
by simply classifying them by their DSCP Precedence Prefix. As
specified above, the DSCP Precedence Prefix are the bits 0-2 od the
DSCP. If classification based on DSCP Precedence Prefix is applied
in an MPLS domain, the DSCP Precedence Prefix my simply be copied
into the MPLS TC field. This is very useful in domains operating
Pen-ultimate hop popping. Also in this case, operation and
configuration of routers can be simplified significantly as compared
to aggregation schemes based on configuring individual DSCPs.
A network provider applying DSCP Precedence Prefix based aggregation
MAY remark incoming DSCPs so that they can be aggregated by their
DSCP Precedence Prefix. To allow for simple carrier interconnection
agreements, carriers sending traffic belonging to the same class but
marked by DSCPs with differing DSCP Precedence Prefixes SHOULD apply
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the interconnection marking and codepoint scheme specified below, if
they interconnect to a carrier applying DSCP Precedence Prefix based
traffic aggregation. An example where this may be required is the
Interactive Class of GSMA IR.34 [IR.34] (note that the author of this
draft believes that the GSMA specification is breaking RFC 2597).
Another option is to negotiate a customised interconnection agreement
of course.
A node forwarding traffic based the DSCP Precedence Prefix MUST
classify this traffic by the DSCP bits 0-2 and it MUST ignore the
bits 4-6 of DSCP for classification. Classification by DSCP
Precedence Prefix is useful for links aggregating DiffServ traffic.
DSCP Precedence Prefix based classification is not recommended as a
general mode of operation. Edge systems, QoS policy enforcement
nodes, service areas and hosts benefit from fine grained DSCP based
classification and should continue to do so.
RFC 2474 specifies the Class Selector Codepoints [RFC2474]. These
offer a similar concept, but they are strictly limited to xxx000
DSCPs. The Class Selector Codepoints don't offer aggregation, they
just simplify classification. This draft intents to aggregate
several PHBs of a single class by a DSCP Precedence Prefix, which a
different concept than that of the Class Selector Codepoints.
4. An Interconnection class and codepoint scheme
DiffServ deployments mostly follow loose class specification schemes
(often one or two AF classes, EF and Best Effort). Especially DSCP
assignment for the AF classes varies between deployments. Basic AF
class property definitions are often similar however. Applying
provider specific DSCPs is in line with the DiffServ architecture.
This document doesn't propose to change that.
Interconnecting parties face the problem of matching classes to be
interconnected and then to agree on codepoint mapping. As stated by
draft DiffServ problem statement
[I-D.polk-tsvwg-diffserv-stds-problem-statement], remarking is a
standard behaviour at interconnection interfaces. This draft
proposes a standard interconnection set of 4 QoS classes with well
defined DSCP and DSCP Precedence Prefix values. A sending party
remarks DSCPs from internal schemes to the Interconnection
codepoints. The receiving party remarks DSCP Precedence Prefixes and
/ or DSCPs to her internal scheme. Thus the interconnection
codepoint scheme fully complies with the DiffServ architecture. An
interconnection class and codepoint scheme was introduced by ITU-T
[Y.1566] (there also including Ethernet). It is specified to a
higher level of detail in this document.
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At first glance, this looks like an additional effort. But there are
obvious benefits: each party sending or receiving traffic has to
specify the mapping from or to the interconnection class and
codepoint scheme only once. Without it, this is to be negotiated per
interconnection party individually. Further, end-to-end QoS in terms
of traffic being classified for the same class in all passed domains
is likely to result if an interconnection codepoint scheme is used.
It is not necessarily resulting from individual per network mapping
negotiations.
The standards and deployments known to the author of this draft are
limited to 4 DiffServ classes at interconnection points (or
less).Draft RFC 4597 update [I-D.polk-tsvwg-rfc4594-update]doesn't
seem to generally contradict to this, as it proposes to standardise
"many services classes, not all will be used in each network at any
period of time." Some reasons favour working with 4 DiffServ
interconnection classes:
o There should be a coding reserve for interconnection classes.
This leaves space for future standards, for private bilateral
agreements and for provider internal classes.
o MPLS and Ethernet support only 8 PHBs, classes or ECN indications.
Assignment of 3 bit codepoints for whatever purpose must be well
thought through. Limiting interconnection QoS to four classes is
MPLS and Ethernet friendly in that sense.
o Migrations from one codepoint scheme to another may require spare
QoS codepoints.
The proposed class and codepoint scheme is designed for point to
point IP layer interconnections. Other types of interconnections are
out of scope of this document. The basic class and codepoint scheme
is applicable on Ethernet layer too.
5. Consolidation of QoS standards by the interconnection codepoint
scheme
The interconnection class and codepoint scheme proposed by Y.1566
also tries to consolidate related DiffServ and QoS standardisation
efforts outside of the IETF [Y.1566]. The interconnection class and
codepoint scheme may be a suitable approach to consolidate these
standards. MEF 23.1 specifies 3 aggregated classes, consuming up to
5 codepoints on Ethernet layer (EF, AF3, AF1 and Best Effort) and 5
PHBs [MEF23.1]. MEF aggregates AF1 and Default PHB in a single
class. This is not recommended for interconnection, as it is not in
line with RFC 2597 (which requires separate forwarding resources for
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each AF class and doesn't foresee aggregation of Default PHB and an
AF class).
GSMA IR.34 proposes four classes, EF, AF4, another AF class and Best
Effort with 7 PHBs in sum [IR.34]. IR.34 specifies an "Interactive"
class consisting of 3 PHBs with different priorities. IR.34 assigns
the PHBS AF31, AF21 and AF11 to this Interactive class. This breaks
RFC 2597. The proposed interconnection class and codepoint scheme
supports an GSMA Interactive like class but assigns AF3 with PHBs
AF31, AF32 and AF33.
If IETF picks up this draft, it may be a good idea to inform MEF and
GSMA about conflicts of their standards with DiffServ and suggest
joint activities to improve the situation. Information on
interworking with MEF 23 and GSMA IR.34 with the interconnection QoS
scheme could be given by a later version of this draft.
The classes to be supported at interconnection interfaces are
specified by Y.1566 as:
Class Priority: EF, expecting the figures of merit describing the
PHB to be in the range of low single digit milliseconds. See
[RFC3246].
Bulk inelastic: Optimised for low loss, low delay, low jitter at
high bandwidth. Traffic load in this class must be
controlled, e.g. by application servers. One example could
be flow admission control. There may be infrequent
retransmissions requested by the application layer to
mitigate low levels of packet losses. Discard of packets
through active queue management should be avoided in this
class. Congestion in this class may result in bursty packet
loss. If used to carry multimedia traffic, it is recommended
to carry audio and video traffic in a single PHB. All of
these properties influence the buffer design.
Assured: This class may be optimised to transport traffic without
bandwidth requirements. It aims on Very low loss at high
bandwidths. Retransmissions after losses characterise the
class and influence the buffer design. Active queue
management with probabilistic dropping may be deployed.
Default: Default. This class may be optimised to transport traffic
without bandwidth requirements. Retransmissions after losses
characterise the class and influence the buffer design.
Active queue management with probabilistic dropping may be
deployed.
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Note that other DiffServ related standards trim down class
requirements to SLA parameters. To quote e.g. RFC 4594-update, "A
"service class" represents a similar set of traffic characteristics
for delay, loss, and jitter as packets traverse routers in a
network." This draft adds traffic PHB properties corresponding to
expected transport layer characteristics as a key factor to a class
definition: the desired class performance like delay, jitter and
worst case loss are met only if PHB and transport properties meet the
ones described by the class definition. This is not to say, the
other standards ignore PHB properties. They are e.g. a core part of
RFC 4594-update. They do not directly refer to transport protocol
properties, as most existing QoS standards prefer the approach of
assigning QoS classes to applications or application sets. This may
result in undesirable class mappings, if an e.g. IP TV application
demanding low loss is matched to a class whose low loss guarantees
depend on AQM mechanisms.
Y.1566 does not define a complete set of DSCP based PHBs to be
supported at an interconnection interface. This information is added
by this draft. At interconnection points, the following DSCP based
PHBs should be accepted between interconnected parties:
Class: PHB (one or more)
Class Priority: EF
Bulk inelastic: AF41 (AF42 and AF43 are reserved for extension)
Assured: AF31, AF32 and AF33
Default: Default (i.e. Best Effort)
Class names (and property specification) have been picked from Y.1566
above.
6. Treatment of Network Control traffic at carrier interconnection
interfaces
As specified by RFC4594, section 3.2, Network Control (NC) traffic
marked by CS6 is to be expected at interconnection interfaces. This
document does not change NC specifications of RFC4594. The latter
specification is detailed on domain internal NC traffic and on
traffic exchanged between peering points. Further, it recommends not
to forward CS6 marked traffic originating from user-controlled end
points by the NC class of a provider domain.
As a minor clarification to RFC4594, "peering" shouldn't be
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interpreted in a commercial sense. The NC PHB is applicable also in
the case of a purchased network service based on a transit agreement
with an upstream provider. RFC4594 recommendations on NC traffic are
applicable for IP carrier interconnections in general.
Some CS6 traffic exchanged accross carrier interconnections will
terminate at the domain ingress node (e.g., if BGP is running between
the two routers on opposite ends of the interconnection link).
An IP carrier MAY limit access to the NC PHB for traffic which is
recognised as network control traffic relevant to the own domain.
Interconnecting carriers SHOULD specify treatment of CS6 marked
traffic received at a carrier interconnection which is to be
forwarded beyond the ingress node. An SLA covering the following
cases is recommended, if a carrier wishes to send CS6 marked traffic
accross an interconnection link which isn't terminating at the
interconnected ingress node:
o classification of traffic which is network control traffic for
both domains. This traffic SHOULD be classified for the NC PHB.
o classification of traffic which is network control traffic for the
sending domain only. This traffic SHOULD be classified for a PHB
offering similar properties as the NC class (e.g. AF31 as
specified by this document).
o any other CS6 marked traffic SHOULD be remarked or dropped.
7. MPLS, Ethernet and DSCP Precedence Prefixes for aggregated classes
Ethernet and MPLS support 3 bit codepoint fields to differentiate
service quality. Mapping of the DSCP Precedence Prefix to these 3
Bit fields has been a configuration restriction in the early days of
DiffServ. The concept of classifying DiffServ traffic classes by the
bits 0-2 of a DSCP has however been part of Diffserv from start on.
EF's DSCP Precedence Prefix is 5, that of AF4 is 4 and so on. The
interconnection class and codepoint scheme respects properties and
limits of a 3 bit PHB coding space in different ways:
o it allows to classify four interconnection classes based on Class
Selector Codepoints.
o it supports a single PHB group (AF3), whose DSCP based PHBs may be
mapped to up to three different MPLS TC's or Ethernet P-Bits.
Note that this draft doesn's favour or recommend doing that, but
it is possible. The author isn't aware of deployed service offers
with 3 different drop levels in a single class.
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The above statement is no requirement to depricate any DSCP to MPLS
TC or Ethernet P-Bit mapping functionality. In the opposite, by
limiting the interconnection scheme to 7 DSCP based PHBs, each PHB
may be mapped to a 3 Bit based PHB scheme.
8. QoS class name selection
This is more of an informational discussion, proposed best practice,
and mainly relates to human behaviour (including QoS experts) rather
than technical issues. Above the human preference for conceivable
class names has been mentioned. Network engineers (including the
former Diffserv WG authors) recommend avoiding application related
QoS class names. Focus should be put on class properties. These can
be irritating again. Just looking at SLA parameters like Delay,
Jitter and packet loss doesn't tell the reader, which transport
properties guided the related scheduler engineering of a PHB. A
router produces QoS with a scheduling mechanism, a settable queue
depth and optional active queue management (including ECN), and may
be a policer. Some kind of resource management may be present (also
in Diffserv domains). It's beyond the imagination of the author how
one would engineer more than half a dozen classes with
distinguishable properties using this set of tools.
There's no perfect solution to the problem, as PHB configurations are
not comprehensible to most readers, even if they were communicated
(they are operational secrets of course). There are (or should be)
engineering assumptions, when designing QoS PHBs. They closer relate
to layer 3 or layer 4 level properties than to specific applications.
In most cases, an application responds to congestion by reducing
traffic, or it ignores congestion. Active queue management doesn't
help to avoid congestion in the latter case, only resource management
does. EF may be a special case. If the EF traffic is not responsive
to congestion, and packets are assumed to be short, rather small
jitter values can be reached if engineering ensures that the packet
arrival rate never exceeds the transmission rate of that queue (see
RFC 3246 [RFC3246]). There's other non congestion-responsive
traffic, for which the EF engineering assumptions may not fit. So
support of a PHB like bulk inelastic is reasonable.
Active queue management may be deployed for QoS classes designed to
transport traffic responding to congestion by traffic reduction.
The class names of this document follow Y.1566. TCP_optimised and
especially UDP_optimised are inappropriate class names, as some UDP
based applications are or may be expected to become TCP friendly.
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9. Allow for DiffServ extendibility on MPLS and Ethernet level
Any aggregated Diffserv deployment faces codepoint depletion issues
rather soon, if deployed on MPLS or Ethernet. Coding space should be
left for new features, like ECN, PCN or Conex. In addition to
carrying customer traffic, internal routing and network management
traffic may be protected by using a separate class. Offering
interconnection with up to four classes and 4 - 6 MPLS TC's (or
Ethernet P-bits) to that respect is probably at least a fair
compromise.
10. Acknowledgements
David Black gave many helpful comments to this work. Al Morton and
Sebastien Jobert provided feedback on many aspects during private
discussions. Brian Carpenter, Mohamed Boucadair and Thomas Knoll
helped adding awareness of further potentially related work.
11. IANA Considerations
This memo includes no request to IANA.
12. Security Considerations
This document does not introduce new features, it describes how to
use existing ones. The security section of RFC 4597 [RFC4597]
applies.
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
[RFC2575] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based
Access Control Model (VACM) for the Simple Network
Management Protocol (SNMP)", RFC 2575, April 1999.
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[RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski,
"Assured Forwarding PHB Group", RFC 2597, June 1999.
[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.
[RFC3260] Grossman, D., "New Terminology and Clarifications for
Diffserv", RFC 3260, April 2002.
[RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen,
P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi-
Protocol Label Switching (MPLS) Support of Differentiated
Services", RFC 3270, May 2002.
[RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching
(MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic
Class" Field", RFC 5462, February 2009.
[min_ref] authSurName, authInitials., "Minimal Reference", 2006.
13.2. Informative References
[I-D.knoll-idr-cos-interconnect]
Knoll, T., "BGP Class of Service Interconnection",
draft-knoll-idr-cos-interconnect-10 (work in progress),
May 2013.
[I-D.polk-tsvwg-diffserv-stds-problem-statement]
Polk, J., "The Problem Statement for the Standard
Configuration of DiffServ Service Classes",
draft-polk-tsvwg-diffserv-stds-problem-statement-00 (work
in progress), July 2012.
[I-D.polk-tsvwg-rfc4594-update]
Polk, J., "Standard Configuration of DiffServ Service
Classes", draft-polk-tsvwg-rfc4594-update-03 (work in
progress), March 2013.
[ID.idr-sla]
IETF, "Inter-domain SLA Exchange", IETF, http://
datatracker.ietf.org/doc/draft-ietf-idr-sla-exchange/,
2013.
[IR.34] GSMA Association, "IR.34 Inter-Service Provider IP
Backbone Guidelines Version 7.0", GSMA, GSMA IR.34 http:/
/www.gsma.com/newsroom/wp-content/uploads/2012/03/
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ir.34.pdf, 2012.
[MEF23.1] MEF, "Implementation Agreement MEF 23.1 Carrier Ethernet
Class of Service Phase 2", MEF, MEF23.1 http://
metroethernetforum.org/PDF_Documents/
technical-specifications/MEF_23.1.pdf, 2012.
[RFC4597] Even, R. and N. Ismail, "Conferencing Scenarios",
RFC 4597, August 2006.
[RFC5127] Chan, K., Babiarz, J., and F. Baker, "Aggregation of
Diffserv Service Classes", RFC 5127, February 2008.
[RFC5160] Levis, P. and M. Boucadair, "Considerations of Provider-
to-Provider Agreements for Internet-Scale Quality of
Service (QoS)", RFC 5160, March 2008.
[Y.1566] ITU-T, "Quality of service mapping and interconnection
between Ethernet, IP and multiprotocol label switching
networks", ITU,
http://www.itu.int/rec/T-REC-Y.1566-201207-I/en, 2012.
Appendix A. Change log
00 to 01 Added terminology and references. Added details and
information to interconnection class and codepoint scheme.
Editorial changes.
01 to 02 Added some references regarding related work. Clarified
class definitions. Further editorial improvements.
02 to 03 Consistent terminology. Discussion of Network Management
PHB at interconnection interfaces. Editorial review.
03 to 04 Again improved terminology. Better wording of Network
Control PHB at interconnection interfaces.
Geib Expires April 21, 2014 [Page 14]
Internet-Draft Abbreviated Title October 2013
Author's Address
Ruediger Geib (editor)
Deutsche Telekom
Heinrich Hertz Str. 3-7
Darmstadt, 64295
Germany
Phone: +49 6151 5812747
Email: Ruediger.Geib@telekom.de
Geib Expires April 21, 2014 [Page 15]
