draft-ietf-mmusic-qos-identification-03.txt   rfc5432.txt 
MMUSIC James Polk Network Working Group J. Polk
Internet-Draft Subha Dhesikan Request for Comments: 5432 S. Dhesikan
Intended status: Standards Track Cisco Systems Category: Standards Track Cisco Systems
Expires: May 22, 2009 Gonzalo Camarillo G. Camarillo
Ericsson Ericsson
November 18, 2008 Quality of Service (QoS) Mechanism Selection
in the Session Description Protocol (SDP)
Quality of Service (QoS) Mechanism Selection in the Session Description
Protocol (SDP)
draft-ietf-mmusic-qos-identification-03.txt
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Abstract Abstract
The offer/answer model for SDP assumes that endpoints establish The offer/answer model for the Session Description Protocol (SDP)
somehow the QoS required for the media streams they establish. assumes that endpoints somehow establish the Quality of Service (QoS)
Endpoints in closed environments typically agree out of band (e.g., required for the media streams they establish. Endpoints in closed
using configuration information) which QoS mechanism to use. environments typically agree out-of-band (e.g., using configuration
However, on the Internet, there is more than one QoS service information) regarding which QoS mechanism to use. However, on the
available. Consequently, there is a need for a mechanism to Internet, there is more than one QoS service available.
negotiate which QoS mechanism to use for a particular media stream. Consequently, there is a need for a mechanism to negotiate which QoS
This document defines such a mechanism. mechanism to use for a particular media stream. This document
defines such a mechanism.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology .....................................................3
3. SDP Attributes Definition . . . . . . . . . . . . . . . . . . 3 3. SDP Attributes Definition .......................................3
4. Offer/answer Behavior . . . . . . . . . . . . . . . . . . . . 4 4. Offer/Answer Behavior ...........................................4
4.1. Offerer Behavior . . . . . . . . . . . . . . . . . . . . . 4 4.1. Offerer Behavior ...........................................4
4.2. Answerer Behavior . . . . . . . . . . . . . . . . . . . . 5 4.2. Answerer Behavior ..........................................4
4.3. Resource Reservation . . . . . . . . . . . . . . . . . . . 5 4.3. Resource Reservation .......................................5
4.4. Subsequent Offer/answer Exchanges . . . . . . . . . . . . 5 4.4. Subsequent Offer/Answer Exchanges ..........................5
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Example .........................................................5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations .............................................6
6.1. Registration of the SDP 'qos-mech-send' Attribute . . . . 6 6.1. Registration of the SDP 'qos-mech-send' Attribute ..........6
6.2. Registration of the SDP 'qos-mech-recv' Attribute . . . . 7 6.2. Registration of the SDP 'qos-mech-recv' Attribute ..........6
6.3. Registry for QoS Mechanism Tokens . . . . . . . . . . . . 7 6.3. Registry for QoS Mechanism Tokens ..........................7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations .........................................7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 8. Acknowledgements ................................................7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 9. References ......................................................8
9.1. Normative References . . . . . . . . . . . . . . . . . . . 8 9.1. Normative References .......................................8
9.2. Informative References . . . . . . . . . . . . . . . . . . 8 9.2. Informative References .....................................8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
1. Introduction 1. Introduction
The offer/answer model [RFC3264] for SDP [RFC4566] does not provide The offer/answer model [RFC3264] for SDP [RFC4566] does not provide
any mechanism for endpoints to negotiate the QoS mechanism to be used any mechanism for endpoints to negotiate the QoS mechanism to be used
for a particular media stream. Even when QoS preconditions [RFC3312] for a particular media stream. Even when QoS preconditions [RFC3312]
are used, the choice of the QoS mechanism is left unspecified, up to are used, the choice of the QoS mechanism is left unspecified and is
the endpoints. up to the endpoints.
Endpoints that support more than one QoS mechanism need a way to Endpoints that support more than one QoS mechanism need a way to
negotiate which one to use for a particular media stream. Examples negotiate which one to use for a particular media stream. Examples
of QoS mechanisms are RSVP (Resource Reservation Protocol) [RFC2205] of QoS mechanisms are RSVP (Resource Reservation Protocol) [RFC2205]
and NSIS (Next Steps in Signaling) [I-D.ietf-nsis-qos-nslp]. and NSIS (Next Steps in Signaling) [QoS-NSLP].
This document defines a mechanism that allows endpoints to negotiate This document defines a mechanism that allows endpoints to negotiate
the QoS mechanism to be used for a particular media stream. However, the QoS mechanism to be used for a particular media stream. However,
the fact that endpoints agree on a particular QoS mechanism does not the fact that endpoints agree on a particular QoS mechanism does not
imply that that particular mechanism is supported by the network. imply that that particular mechanism is supported by the network.
Discovering which QoS mechanisms are supported at the network layer Discovering which QoS mechanisms are supported at the network layer
is out of the scope of this document. In any case, the information is out of the scope of this document. In any case, the information
the endpoints exchange to negotiate QoS mechanisms, as defined in the endpoints exchange to negotiate QoS mechanisms, as defined in
this document, can be useful for a network operator to resolve a this document, can be useful for a network operator to resolve a
subset of the QoS interoperability problem, namely to ensure that a subset of the QoS interoperability problem -- namely, to ensure that
mechanism commonly acceptable to the endpoints is chosen and make it a mechanism commonly acceptable to the endpoints is chosen and make
possible to debug possible misconfiguration situations. it possible to debug potential misconfiguration situations.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. SDP Attributes Definition 3. SDP Attributes Definition
This document defines the 'qos-mech-send' and 'qos-mech-recv' session This document defines the 'qos-mech-send' and 'qos-mech-recv' session
and media-level SDP [RFC4566] attributes. The following is their and media-level SDP [RFC4566] attributes. The following is their
augmented Backus-Naur Form (BNF) [RFC5234] syntax, which is based on Augmented Backus-Naur Form (ABNF) [RFC5234] syntax, which is based on
the SDP [RFC4566] grammar: the SDP [RFC4566] grammar:
attribute =/ qos-mech-send-attr attribute =/ qos-mech-send-attr
attribute =/ qos-mech-recv-attr attribute =/ qos-mech-recv-attr
qos-mech-send-attr = "qos-mech-send" ":" qos-mech-send-attr = "qos-mech-send" ":"
[[SP] qos-mech *(SP qos-mech)] [[SP] qos-mech *(SP qos-mech)]
qos-mech-recv-attr = "qos-mech-recv" ":" qos-mech-recv-attr = "qos-mech-recv" ":"
[[SP] qos-mech *(SP qos-mech)] [[SP] qos-mech *(SP qos-mech)]
skipping to change at page 4, line 28 skipping to change at page 4, line 16
in a 'qos-mech-send' attribute identifies a QoS mechanism that can be in a 'qos-mech-send' attribute identifies a QoS mechanism that can be
used to reserve resources for traffic sent by the entity generating used to reserve resources for traffic sent by the entity generating
the session description. A token that appears in a 'qos-mech-recv' the session description. A token that appears in a 'qos-mech-recv'
attribute identifies a QoS mechanism that can be used to reserve attribute identifies a QoS mechanism that can be used to reserve
resources for traffic received by the entity generating the session resources for traffic received by the entity generating the session
description. description.
The 'qos-mech-send' and 'qos-mech-recv' attributes are not The 'qos-mech-send' and 'qos-mech-recv' attributes are not
interdependent; one can be used without the other. interdependent; one can be used without the other.
The following is an example of an 'm' line with a 'qos-mech-send' and The following is an example of an 'm' line with 'qos-mech-send' and
a 'qos-mech-recv' attributes: 'qos-mech-recv' attributes:
m=audio 50000 RTP/AVP 0 m=audio 50000 RTP/AVP 0
a=qos-mech-send: rsvp nsis a=qos-mech-send: rsvp nsis
a=qos-mech-recv: rsvp nsis a=qos-mech-recv: rsvp nsis
4. Offer/answer Behavior 4. Offer/Answer Behavior
An offer/answer exchange using the 'qos-mech-send' and 'qos-mech- Through the use of the 'qos-mech-send' and 'qos-mech-recv'
recv' attributes allows endpoints to come up with a list of common attributes, an offer/answer exchange allows endpoints to come up with
QoS mechanisms sorted by preference. However, note that endpoints a list of common QoS mechanisms sorted by preference. However, note
negotiate in which direction QoS is needed using other mechanisms, that endpoints negotiate in which direction QoS is needed using other
such as preconditions [RFC3312]. Endpoints may also use other mechanisms, such as preconditions [RFC3312]. Endpoints may also use
mechanisms to negotiate, if needed, the parameters to use with a other mechanisms to negotiate, if needed, the parameters to use with
given QoS mechanism (e.g., bandwidth to be reserved). a given QoS mechanism (e.g., bandwidth to be reserved).
4.1. Offerer Behavior 4.1. Offerer Behavior
Offerers include a 'qos-mech-send' attribute with the tokens Offerers include a 'qos-mech-send' attribute with the tokens
corresponding to the QoS mechanisms supported in the send direction corresponding to the QoS mechanisms (in order of preference) that are
in order of preference. Similarly, offerers include a 'qos-mech- supported in the send direction. Similarly, offerers include a
recv' attribute with the tokens corresponding to the QoS mechanisms 'qos-mech-recv' attribute with the tokens corresponding to the QoS
supported in the receive direction in order of preference. mechanisms (in order of preference) that are supported in the receive
direction.
4.2. Answerer Behavior 4.2. Answerer Behavior
On receiving an offer with a set of tokens in a 'qos-mech-send' On receiving an offer with a set of tokens in a 'qos-mech-send'
attribute, the answerer takes those tokens corresponding to QoS attribute, the answerer takes those tokens corresponding to QoS
mechanisms it supports in the receive direction and includes them, in mechanisms that it supports in the receive direction and includes
order of preference, in a 'qos-mech-recv' attribute in the answer. them, in order of preference, in a 'qos-mech-recv' attribute in the
On receiving an offer with a set of tokens in a 'qos-mech-recv' answer. On receiving an offer with a set of tokens in a 'qos-mech-
attribute, the answerer takes those tokens corresponding to QoS recv' attribute, the answerer takes those tokens corresponding to QoS
mechanisms it supports in the send direction and includes them, in mechanisms that it supports in the send direction and includes them,
order of preference, in a 'qos-mech-send' attribute in the answer. in order of preference, in a 'qos-mech-send' attribute in the answer.
When ordering the tokens in a 'qos-mech-send' or a 'qos-mech-recv' When ordering the tokens in a 'qos-mech-send' or a 'qos-mech-recv'
attribute by preference, the answerer may take into account its own attribute by preference, the answerer may take into account its own
preferences and those expressed in the offer. However, the exact preferences and those expressed in the offer. However, the exact
algorithm to be used to order such token lists is outside the scope algorithm to be used to order such token lists is outside the scope
of this specification. of this specification.
Note that if the answerer does not have any QoS mechanism in common Note that if the answerer does not have any QoS mechanism in common
with the offerer, it will return empty 'qos-mech-send' and 'qos-mech- with the offerer, it will return empty 'qos-mech-send' and 'qos-mech-
recv' attributes. recv' attributes.
4.3. Resource Reservation 4.3. Resource Reservation
Once the offer/answer exchange completes, both offerer and answerer Once the offer/answer exchange completes, both offerer and answerer
use the token lists in the 'qos-mech-send' and 'qos-mech-recv' use the token lists in the 'qos-mech-send' and 'qos-mech-recv'
attributes of the answer to perform resource reservations. Offerers attributes of the answer to perform resource reservations. Offerers
and answerers SHOULD attempt to use the QoS mechanism with highest and answerers SHOULD attempt to use the QoS mechanism with highest
priority in each direction first. If an endpoint (the offerer or the priority in each direction first. If an endpoint (the offerer or the
answerer) does not succeed using the mechanism with highest priority answerer) does not succeed in using the mechanism with highest
in a given direction, it SHOULD attempt to use the next QoS mechanism priority in a given direction, it SHOULD attempt to use the next QoS
in order of priority in that direction, and so on. mechanism in order of priority in that direction, and so on.
If an endpoint tries unsuccessfully all the common QoS mechanisms for If an endpoint unsuccessfully tries all the common QoS mechanisms for
a given direction, the endpoint MAY attempt to use additional QoS a given direction, the endpoint MAY attempt to use additional QoS
mechanisms not supported by the remote endpoint. This is because mechanisms not supported by the remote endpoint. This is because
there may be network entities out of the endpoint's control (e.g., an there may be network entities out of the endpoint's control (e.g., an
RSVP proxy) that make those mechanisms work. RSVP proxy) that make those mechanisms work.
4.4. Subsequent Offer/answer Exchanges 4.4. Subsequent Offer/Answer Exchanges
If, during an established session for which the QoS mechanism to be If, during an established session for which the QoS mechanism to be
used for a given direction was agreed using the mechanism defined in used for a given direction was agreed upon using the mechanism
this specification, an endpoint receives a subsequent offer that does defined in this specification, an endpoint receives a subsequent
not contain the QoS selection attribute corresponding to that offer that does not contain the QoS selection attribute corresponding
direction (i.e., the 'qos-mech-send' or 'qos-mech-recv' attribute is to that direction (i.e., the 'qos-mech-send' or 'qos-mech-recv'
missing), the endpoints SHOULD continue using the same QoS mechanism attribute is missing), the endpoints SHOULD continue using the same
used up to that moment. QoS mechanism used up to that moment.
5. Example 5. Example
The following is an offer/answer exchange between two endpoints using The following is an offer/answer exchange between two endpoints using
the 'qos-mech-send' and 'qos-mech-recv' attributes. Parts of the the 'qos-mech-send' and 'qos-mech-recv' attributes. Parts of the
session descriptions are ommitted for clarity purposes. session descriptions are omitted for clarity purposes.
The offerer generates the following session description listing both The offerer generates the following session description, listing both
RSVP and NSIS for both directions. The offerer would prefer to use RSVP and NSIS for both directions. The offerer would prefer to use
RSVP and, thus, includes it before NSIS. RSVP and, thus, includes it before NSIS.
m=audio 50000 RTP/AVP 0 m=audio 50000 RTP/AVP 0
a=qos-mech-send: rsvp nsis a=qos-mech-send: rsvp nsis
a=qos-mech-recv: rsvp nsis a=qos-mech-recv: rsvp nsis
The answerer supports NSIS in both directions, but not RSVP. The answerer supports NSIS in both directions, but not RSVP.
Consequently, it returns the following session description: Consequently, it returns the following session description:
skipping to change at page 6, line 33 skipping to change at page 6, line 23
a=qos-mech-send: nsis a=qos-mech-send: nsis
a=qos-mech-recv: nsis a=qos-mech-recv: nsis
6. IANA Considerations 6. IANA Considerations
This specification registers two new SDP attributes and creates a new This specification registers two new SDP attributes and creates a new
registry for QoS mechanisms. registry for QoS mechanisms.
6.1. Registration of the SDP 'qos-mech-send' Attribute 6.1. Registration of the SDP 'qos-mech-send' Attribute
This section instructs the IANA to register the following SDP att- IANA has registered the following SDP att-field under the Session
field under the Session Description Protocol (SDP) Parameters Description Protocol (SDP) Parameters registry:
registry:
Contact name: Gonzalo.Camarillo@ericsson.com Contact name: Gonzalo.Camarillo@ericsson.com
Attribute name: qos-mech-send Attribute name: qos-mech-send
Long-form attribute name: QoS Mechanism for the Send Direction Long-form attribute name: QoS Mechanism for the Send Direction
Type of attribute Session and Media levels Type of attribute: Session and Media levels
Subject to charset: No Subject to charset: No
Purpose of attribute: To list QoS mechanisms supported in the send Purpose of attribute: To list QoS mechanisms supported in the send
direction. direction
Allowed attribute values: IANA Registered Tokens Allowed attribute values: IANA Registered Tokens
6.2. Registration of the SDP 'qos-mech-recv' Attribute 6.2. Registration of the SDP 'qos-mech-recv' Attribute
This section instructs the IANA to register the following SDP att- IANA has registered the following SDP att-field under the Session
field under the Session Description Protocol (SDP) Parameters Description Protocol (SDP) Parameters registry:
registry:
Contact name: Gonzalo.Camarillo@ericsson.com Contact name: Gonzalo.Camarillo@ericsson.com
Attribute name: qos-mech-recv Attribute name: qos-mech-recv
Long-form attribute name: QoS Mechanism for the Receive Direction Long-form attribute name: QoS Mechanism for the Receive Direction
Type of attribute Session and Media levels Type of attribute: Session and Media levels
Subject to charset: No Subject to charset: No
Purpose of attribute: To list QoS mechanisms supported in the Purpose of attribute: To list QoS mechanisms supported in the
receive direction. receive direction
Allowed attribute values: IANA Registered Tokens Allowed attribute values: IANA Registered Tokens
6.3. Registry for QoS Mechanism Tokens 6.3. Registry for QoS Mechanism Tokens
The IANA is requested to create a subregistry for QoS mechanism token The IANA has created a subregistry for QoS mechanism token values to
values to be used in the 'qos-mech-send' and 'qos-mech-recv' be used in the 'qos-mech-send' and 'qos-mech-recv' attributes under
attributes under the Session Description Protocol (SDP) Parameters the Session Description Protocol (SDP) Parameters registry. The
registry. The initial values for the subregistry are presented in initial values for the subregistry are as follows:
the following, and IANA is requested to add them into its database:
QoS Mechanism Reference QoS Mechanism Reference
---------------------------- --------- ---------------------------- ---------
rsvp RFC xxxx rsvp RFC 5432
nsis RFC xxxx nsis RFC 5432
[RFC Editor's note: please replace 'RFC xxxx' with the number this
RFC will get.]
As per the terminology in [RFC5226], the registration policy for new As per the terminology in [RFC5226], the registration policy for new
QoS mechanism token values shall be 'Specification Required'. QoS mechanism token values shall be 'Specification Required'.
7. Security Considerations 7. Security Considerations
An attacker may attempt to add, modify, or remove 'qos-mech-send' and An attacker may attempt to add, modify, or remove 'qos-mech-send' and
'qos-mech-recv' attributes from a session description. This could 'qos-mech-recv' attributes from a session description. This could
result in an application behaving in a non-desirable way. For result in an application behaving in a non-desirable way. For
example, the endpoints under attack may not be able to find a common example, the endpoints under attack may not be able to find a common
skipping to change at page 8, line 28 skipping to change at page 8, line 13
Westerlund provided useful comments on this specification. Westerlund provided useful comments on this specification.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264, June
June 2002. 2002.
[RFC3851] Ramsdell, B., "Secure/Multipurpose Internet Mail [RFC3851] Ramsdell, B., Ed., "Secure/Multipurpose Internet Mail
Extensions (S/MIME) Version 3.1 Message Specification", Extensions (S/MIME) Version 3.1 Message Specification",
RFC 3851, July 2004. RFC 3851, July 2004.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for
Specifications: ABNF", STD 68, RFC 5234, January 2008. Syntax Specifications: ABNF", STD 68, RFC 5234, January
2008.
9.2. Informative References 9.2. Informative References
[I-D.ietf-nsis-qos-nslp] [QoS-NSLP] Manner, J., Karagiannis, G., and A. McDonald, "NSLP for
Manner, J., Karagiannis, G., and A. McDonald, "NSLP for Quality-of-Service Signaling", Work in Progress, February
Quality-of-Service Signaling", draft-ietf-nsis-qos-nslp-16 2008.
(work in progress), February 2008.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997. Functional Specification", RFC 2205, September 1997.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002. June 2002.
[RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg, [RFC3312] Camarillo, G., Ed., Marshall, W., Ed., and J. Rosenberg,
"Integration of Resource Management and Session Initiation "Integration of Resource Management and Session Initiation
Protocol (SIP)", RFC 3312, October 2002. Protocol (SIP)", RFC 3312, October 2002.
Authors' Addresses Authors' Addresses
James Polk James Polk
Cisco Systems Cisco Systems
3913 Treemont Circle 3913 Treemont Circle
Colleyville, Texas 76034 Colleyville, Texas 76034
USA USA
Phone: +1-817-271-3552 Phone: +1-817-271-3552
Email: jmpolk@cisco.com EMail: jmpolk@cisco.com
Subha Dhesikan Subha Dhesikan
Cisco Systems Cisco Systems
170 W. Tasman Drive 170 W. Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
USA USA
Email: sdhesika@cisco.com EMail: sdhesika@cisco.com
Gonzalo Camarillo Gonzalo Camarillo
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 Jorvas 02420
Finland Finland
Email: Gonzalo.Camarillo@ericsson.com EMail: Gonzalo.Camarillo@ericsson.com
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such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
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