draft-ietf-sipping-multiple-refer-00.txt   draft-ietf-sipping-multiple-refer-01.txt 
SIPPING Working Group G. Camarillo SIPPING Working Group G. Camarillo
Internet-Draft Ericsson Internet-Draft Ericsson
Expires: January 5, 2005 A. Niemi Expires: March 24, 2005 A. Niemi
H. Khartabil H. Khartabil
M. Isomaki M. Isomaki
M. Garcia-Martin M. Garcia-Martin
Nokia Nokia
July 7, 2004 September 23, 2004
Refering to Multiple Resources in the Session Initiation Protocol Refering to Multiple Resources in the Session Initiation Protocol
(SIP) (SIP)
draft-ietf-sipping-multiple-refer-00.txt draft-ietf-sipping-multiple-refer-01.txt
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2004).
Abstract Abstract
This document defines extensions to the SIP REFER method so that this This document defines extensions to the SIP REFER method so that this
method can be used to refer servers to multiple resources. These method can be used to refer servers to multiple resources. These
extensions include the use of pointers to URI-lists in the Refer-To extensions include the use of pointers to Uniform Resource Identifier
header field and the multiple-refer SIP option-tag. (URI)-lists in the Refer-To header field and the "multiple-refer" SIP
option-tag.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview of operation . . . . . . . . . . . . . . . . . . . . 3 3. Overview of operation . . . . . . . . . . . . . . . . . . . 3
4. The multiple-refer SIP Option-Tag . . . . . . . . . . . . . . 4 4. The multiple-refer SIP Option-Tag . . . . . . . . . . . . . 4
5. Suppressing REFER's Implicit Subscription . . . . . . . . . . 4 5. Suppressing REFER's Implicit Subscription . . . . . . . . . 4
6. Behavior of SIP User Agents . . . . . . . . . . . . . . . . . 5 6. Behavior of SIP REFER-Issuers . . . . . . . . . . . . . . . 5
6.1 Behavior of SIP REFER-Issuers . . . . . . . . . . . . . . 5 7. Behavior of REFER-Recipients . . . . . . . . . . . . . . . . 5
6.2 Behavior of REFER-Recipients . . . . . . . . . . . . . . . 5 8. Default URI-List Format . . . . . . . . . . . . . . . . . . 5
7. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 10. Security Considerations . . . . . . . . . . . . . . . . . . 9
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1 Normative References . . . . . . . . . . . . . . . . . . . . 7 12.1 Normative References . . . . . . . . . . . . . . . . . . . 9
10.2 Informational References . . . . . . . . . . . . . . . . . . 8 12.2 Informational References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . 12
1. Introduction 1. Introduction
The SIP REFER method [5] allows a user agent to request a server to The SIP [3] REFER method [5] allows a user agent to request a server
send a request to a third party. Still, a number of applications need to send a request to a third party. Still, a number of applications
to request a server to initiate transactions towards a set of need to request a server to initiate transactions towards a set of
destinations. In one example, the moderator of a conference may want destinations. In one example, the moderator of a conference may want
the conference server to send BYE requests to a group of the conference server to send BYE requests to a group of
participants. In another example, the same moderator may want the participants. In another example, the same moderator may want the
conference server to INVITE a set of new participants. conference server to INVITE a set of new participants.
We define an extension to REFER so that REFER can be used to refer We define an extension to REFER so that REFER can be used to refer
servers to multiple destinations. In addition, we use the REFER servers to multiple destinations. In addition, we use the REFER
extension defined in [7] which suppresses REFER's implicit extension defined in [7] which suppresses REFER's implicit
subscription. subscription.
skipping to change at page 3, line 32 skipping to change at page 3, line 32
In this document, the key words "MUST", "MUST NOT", "REQUIRED", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
described in BCP 14, RFC 2119 [1] and indicate requirement levels for described in BCP 14, RFC 2119 [1] and indicate requirement levels for
compliant implementations. compliant implementations.
We define the following three new terms: We define the following three new terms:
REFER-Issuer: the user agent issuing the REFER request. REFER-Issuer: the user agent issuing the REFER request.
REFER-Recipient: the user agent receiving the REFER request. REFER-Recipient: the user agent receiving the REFER request.
REFER-Target: the user agent designated in the Refer-To URI. REFER-Target: the intended final recipient of the request to be
generated by the REFER-Recipient.
3. Overview of operation 3. Overview of operation
This document defines an extension to the SIP REFER method [5] that This document defines an extension to the SIP REFER method [5] that
allows a SIP UAC to include a list of REFER-Targets in a REFER allows a SIP User Agent Client (UAC) to include a list of
request and send it to a server. The server will create a new request REFER-Targets in a REFER request and send it to a server. The server
for each entry in the list of REFER-Target URIs. will create a new request for each entry in the list of REFER-Target
URIs.
We represent the multiple REFER-Targets of a REFER using the URI-list We represent the multiple REFER-Targets of a REFER using a URI-list.
format specified in [8]. A UAC (User Agent Client) that wants to A UAC (User Agent Client) that wants to refer a server to a set of
refer a server to a set of destinations creates a SIP REFER request. destinations creates a SIP REFER request. The Refer-To header
The Refer-To header contains a pointer to a URI-list, which is contains a pointer to a URI-list, which is included in a body part,
included in a body part, and two option-tags in the Required header and an option-tag in the Required header field: "multiple-refer".
field: "multiple-refer" and "norefersub". The former indicates the This option-tag indicates the requirement to support the
requirement to support the functionality described in this functionality described in this specification.
specification and the latter removes the implicit subscription
associated to REFER requests by default.
When the server receives such request it creates a new request per When the server receives such request it creates a new request per
destination and sends them. destination and sends them.
This document does not provide any mechanism for UACs to find out This document does not provide any mechanism for UACs to find out
about the results of a REFER with multiple REFER-Targets. about the results of a REFER with multiple REFER-Targets.
Furthermore, we do not provide support for the implicit subscription Furthermore, it does not provide support for the implicit
mechanism that is part of the SIP REFER method. The way UACs are kept subscription mechanism that is part of the SIP REFER method. The way
informed about the results of a REFER is service specific. For UACs are kept informed about the results of a REFER is service
example, a UAC sending a REFER to INVITE a set of participants to a specific. For example, a UAC sending a REFER to INVITE a set of
conference may discover which participants were successfully brought participants to a conference may discover which participants were
in into the conference by using the conference package [10] successfully brought into the conference by subscribing to the
conference state event [9].
4. The multiple-refer SIP Option-Tag 4. The multiple-refer SIP Option-Tag
We define a new SIP option-tag for the Require and Supported header We define a new SIP option-tag for the Require and Supported header
fields: "multiple-refer". fields: "multiple-refer".
A user agent including the "multiple-refer" option-tag in a Supported A user agent including the "multiple-refer" option-tag in a Supported
header indicates compliance with this specification. header indicates compliance with this specification.
A user agent generating a REFER with a pointer to a URI-list in its A user agent generating a REFER with a pointer to a URI-list in its
Refer-To header field MUST include the "multiple-refer" option-tag in Refer-To header field MUST include the "multiple-refer" option-tag in
the Require header field of the REFER. the Require header field of the REFER.
5. Suppressing REFER's Implicit Subscription 5. Suppressing REFER's Implicit Subscription
REFER requests with a single REFER-Target establish a subscription REFER requests with a single REFER-Target establish implicitly a
implicitly. The REFER-Issuer is informed about the result of the subscription to the refer event. The REFER-Issuer is informed about
transaction towards the REFER-Target through this implicit the result of the transaction towards the REFER-Target through this
subscription. implicit subscription. As described in RFC 3515 [5], NOTIFY requests
sent as a result of an implicit subscription created by a REFER
request contain a body of type "message/sipfrag" [4] that describes
the status of the transaction initiated by the REFER-Recipient.
In the case of a REFER-Issuer that generates a REFER with multiple In the case of a REFER-Issuer that generates a REFER with multiple
REFER-targets, the REFER-Issuer is typically already subscribed to REFER-targets, the REFER-Issuer is typically already subscribed to
other event package that can provide the information about the result other event package that can provide the information about the result
of the transactions towards the REFER-Targets. For example, a of the transactions towards the REFER-Targets. For example, a
moderator instructing a conference server to send a BYE request to a moderator instructing a conference server to send a BYE request to a
set of participants is usually subscribed to the conference state set of participants is usually subscribed to the conference state
event package for the conference. Notifications to this event package event package for the conference. Notifications to this event
will keep the moderator and the rest of the subscribers informed of package will keep the moderator and the rest of the subscribers
the current list of conference participant. informed of the current list of conference participants.
Consequently, we have decided to remove the implicit subscription Most of the applications using multiple REFER do not need its
from a multiple REFER request. So, a SIP REFER-Issuer generating a implicit subscription. Consequently, a SIP REFER-Issuer generating a
REFER request with multiple REFER-Targets MUST include the REFER request with multiple REFER-Targets SHOULD include the
'norefersub' option-tag in a Require header field to indicate that no "norefersub" option-tag in a Require header field to indicate that no
notifications about the requests should be sent to the REFER-Issue. notifications about the requests should be sent to the REFER-Issuer.
The 'norefersub' SIP option-tag is defined in [7] and suppresses the The "norefersub" SIP option-tag is defined in [7] and suppresses the
REFER's implicit subscription. REFER's implicit subscription.
6. Behavior of SIP User Agents At the time of writing, there is no extension that allows to report
the status of several transactions over a REFER's implicit
Implementations of this specification MUST suppot the transfer subscription. That is the motivation for this document to recommend
mechanism for URI-lists defined in [8]. the usage of the "norefersub" option-tag. If in the future such an
extension is defined, REFER-Issuers using it could refrain from using
the "norefersub" option-tag and use the new extension instead.
6.1 Behavior of SIP REFER-Issuers 6. Behavior of SIP REFER-Issuers
As indicated in Section 4 and Section 5 a SIP REFER-Issuer that As indicated in Section 4 and Section 5 a SIP REFER-Issuer that
creates a REFER request with multiple REFER-Targets includes a creates a REFER request with multiple REFER-Targets includes a
"multiple-refer" and a "norefersub" option-tags in the Require header "multiple-refer" and a "norefersub" option-tags in the Require header
field. field.
The Refer-To header field of a REFER request with multiple The Refer-To header field of a REFER request with multiple
REFER-Targets MUST contain a pointer (i.e., a Content-ID URL [2]) REFER-Targets MUST contain a pointer (i.e., a Content-ID Uniform
that points to the body part (whose disposition type is "uri-list") Resource Locator (URL) [2]) that points to the body part that carries
that carries the URI-list. the URI-list.
As described in [8], the default format for URI-lists in SIP is the 7. Behavior of REFER-Recipients
XCAP resource list format [6]. Still, specific services need to
describe which information clients should include in their URI lists,
as described in [8].
SIP REFER-Issuers generating REFERs with multiple REFER-Targets The REFER-Recipient follows the rules in Section 2.4.2 of RFC 3515
SHOULD use flat lists (i.e., no hierarchical lists), SHOULD NOT use [5] to determine the status code of the response to the REFER.
any entry's attributes but "uri", and SHOULD NOT include any elements
inside entries but "display-name" elements.
6.2 Behavior of REFER-Recipients The REFER-Recipient follows the rules in RFC 3515 [5] to generate the
necessary requests towards the REFER-Targets, acting as if it had
received a regular (no URI-list) REFER per each URI in the URI-list.
8. Default URI-List Format
The default format for URI-list bodies used in a multiple REFER
request is the resource list document specified in [6]. User agents
able to generate or receive REFERs with multiple REFER-Targets MUST
support this format as specified in [6] and MAY support other
formats.
Nevertheless, the Extensible Markup Language (XML) Configuration
Access Protocol (XCAP) resource list document provides features, such
as hierarchical lists and the ability to include entries by reference
relative to the XCAP root URI, that are not needed by the multiplet
REFER service defined in this document. Therefore, when using the
default resource list document, SIP REFER-Issuers generating REFERs
with multiple REFER-Targets SHOULD use flat lists (i.e., no
hierarchical lists) and SHOULD NOT use <entry-ref> elements.
A REFER-Recipient receiving a URI-list with more information than A REFER-Recipient receiving a URI-list with more information than
what we have described in Section 6.1 SHOULD discard all the extra what has just been described MAY discard all the extra information.
information.
The REFER-Recipient follows the rules in Section 2.4.2 of RFC 3515 Figure 1 shows an example of a flat list that follows the resource
[5] to determine the status code of the response to the REFER. list document.
7. Example <?xml version="1.0" encoding="UTF-8"?>
<resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<list>
<entry uri="sip:bill@example.com" />
<entry uri="sip:joe@example.org" />
<entry uri="sip:ted@example.net" />
</list>
</resource-lists>
The following is an example of a REFER request with multiple Figure 1: URI List
REFER-Targets. The REFER's Refer-To header field carries a pointer to
the message body, which carries a list with the URIs of the
REFER-Targets. The REFER's Require header field carries both the
"multiple-refer" and the "norefersub" option-tags.
REFER sip:conf-123@example.com 9. Example
SIP/2.0 Via: SIP/2.0/TCP client.chicago.example.com
Figure 2 shows an example flow where a REFER-Issuer sends a
multiple-REFER request to a REFER-Recipient. The REFER-Recipient
generates a BYE request per REFER-Target.
+--------+ +---------+ +--------+ +--------+ +--------+
| REFER | | REFER | | REFER | | REFER | | REFER |
| issuer | |recipient| |target 1| |target 2| |target 3|
+--------+ +---------+ +--------+ +--------+ +--------+
| 1. REFER | | | |
| ---------------->| | | |
| 2. 202 Accepted | | | |
|<---------------- | 3. BYE | | |
| | ------------->| | |
| | 4. BYE | | |
| | ------------------------->| |
| | 5. BYE | | |
| | ------------------------------------->|
| | 6. 200 OK | | |
| |<------------- | | |
| | 7. 200 OK | | |
| |<------------------------- | |
| | 8. 200 OK | | |
| |<------------------------------------- |
| | | | |
| | | | |
| | | | |
Figure 2: Example flow or a REFER request containin multiple
REFER-Targets
The REFER request (1) contains a Refer-To header field that includes
a pointer to the message body, which carries a list with the URIs of
the REFER-Targets. The REFER's Require header field carries both the
"multiple-refer" and the "norefersub" option-tags. Figure 3 shows an
example of this REFER request. The resource list document contains
the list of REFER-Target URIs along with the method of the SIP
request that the REFER-Recipient generates.
REFER sip:conf-123@example.com SIP/2.0
Via: SIP/2.0/TCP client.chicago.example.com
;branch=z9hG4bKhjhs8ass83 ;branch=z9hG4bKhjhs8ass83
Max-Forwards: 70 Max-Forwards: 70
To: Conference 123 <sip:conf-123@example.com> To: "Conference 123" <sip:conf-123@example.com>
From: Carol <sip:carol@chicago.example.com>;tag=32331 From: Carol <sip:carol@chicago.example.com>;tag=32331
Call-ID: d432fa84b4c76e66710 Call-ID: d432fa84b4c76e66710
CSeq: 2 REFER CSeq: 2 REFER
Contact: <sip:carol@client.chicago.example.com> Contact: <sip:carol@client.chicago.example.com>
Refer-To: <cid:cn35t8jf02@example.com> Refer-To: <cid:cn35t8jf02@example.com>
Require: multiple-refer, norefersub Require: multiple-refer, norefersub
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY
Allow-Events: dialog Allow-Events: dialog
Accept: application/sdp, message/sipfrag Accept: application/sdp, message/sipfrag
Content-Type: application/resource-lists+xml Content-Type: application/resource-lists+xml
Content-Disposition: uri-list Content-Disposition: uri-list
Content-Length: 307 Content-Length: 307
Content-ID: <cn35t8jf02@example.com> Content-ID: <cn35t8jf02@example.com>
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<resource-lists xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<list> <list>
<entry uri="sip:bill@example.com?method=BYE" /> <entry uri="sip:bill@example.com?method=BYE" />
<entry uri="sip:joe@example.org?method=BYE" /> <entry uri="sip:joe@example.org?method=BYE" />
<entry uri="sip:ted@example.net?method=BYE" /> <entry uri="sip:ted@example.net?method=BYE" />
</list> </list>
</resource-lists> </resource-lists>
Figure 1: REFER request with multiple REFER-Targets Figure 3: REFER request with multiple REFER-Targets
8. Security Considerations Figure 4 shows an example of the BYE request (3) that the
REFER-Recipient sends to the first REFER-Target.
The Security Considerations Section of the Requirements and Framework REFER sip:bill@example.com SIP/2.0
for SIP URI-List Services [9] discusses issues related to SIP Via: SIP/2.0/TCP conference.example.com
URI-list services. Given that a server accepting REFERs with multiple ;branch=z9hG4bKhjhs8assmm
REFER-targets acts as an URI-list service, implementations of this Max-Forwards: 70
type of server MUST follow the security-related rules in [9]. These From: "Conference 123" <sip:conf-123@example.com>;tag=88734
rules include mandatory authentication and authorization of clients, To: <sip:bill@example.com>;tag=29872
and opt-in lists. Call-ID: d432fa84b4c34098s812
CSeq: 34 BYE
Content-Length: 0
Figure 4: BYE request
10. Security Considerations
The Framework and Security Considerations for SIP URI-List Services
[8] discusses issues related to SIP URI-list services. Given that a
server accepting REFERs with multiple REFER-targets acts as an
URI-list service, implementations of this type of server MUST follow
the security-related rules in [8]. These rules include mandatory
authentication and authorization of clients, and opt-in lists.
Additionally, servers SHOULD only accept REFER requests within the Additionally, servers SHOULD only accept REFER requests within the
context of an application the server understands (e.g., a context of an application the server understands (e.g., a
conferencing application). This implies that servers MUST NOT accept conferencing application). This implies that servers MUST NOT accept
REFERs for methods they do not understand. The idea behind these two REFERs for methods they do not understand. The idea behind these two
rules is that servers are not used as dumb servers whose only rules is that servers are not used as dumb servers whose only
function is to fan-out random messages they do not understand. function is to fan-out random messages they do not understand.
9. IANA Considerations 11. IANA Considerations
This document defines a SIP option-tag (multiple-refer) in Section 4. This document defines a new SIP option-tag: "multiple-refer". This
This option-tag should be registered in the SIP parameter registry option-tag should be registered in the SIP parameter registry at:
(http://www.iana.org/assignments/sip-parameters).
SIP user agents that place the multiple-refer option-tag in a http://www.iana.org/assignments/sip-parameters
Supported header field understand REFER requests with multiple
REFER-Targets.
10. References SIP user agents that place the "multiple-refer" option-tag in a
Supported header field understand REFER requests that contain
resource list document describing multiple REFER-Targets.
10.1 Normative References 12. References
12.1 Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Levinson, E., "Content-ID and Message-ID Uniform Resource [2] Levinson, E., "Content-ID and Message-ID Uniform Resource
Locators", RFC 2392, August 1998. Locators", RFC 2392, August 1998.
[3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., [3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002. Session Initiation Protocol", RFC 3261, June 2002.
[4] Sparks, R., "Internet Media Type message/sipfrag", RFC 3420, [4] Sparks, R., "Internet Media Type message/sipfrag", RFC 3420,
November 2002. November 2002.
[5] Sparks, R., "The Session Initiation Protocol (SIP) Refer [5] Sparks, R., "The Session Initiation Protocol (SIP) Refer
Method", RFC 3515, April 2003. Method", RFC 3515, April 2003.
[6] Rosenberg, J., "An Extensible Markup Language (XML) [6] Rosenberg, J., "Extensible Markup Language (XML) Formats for
Configuration Access Protocol (XCAP) Usage for Presence Lists", Representing Resource Lists",
draft-ietf-simple-xcap-list-usage-02 (work in progress), draft-ietf-simple-xcap-list-usage-03 (work in progress), July
February 2004.
[7] Olson, S., "Extended-REFER framework and other REFER
extensions", draft-olson-sipping-refer-extensions-01 (work in
progress), February 2004.
[8] Camarillo, G., "Providing a Session Initiation Protocol (SIP)
Application Server with a List of URIs",
draft-camarillo-sipping-uri-list-01 (work in progress), February
2004. 2004.
[9] Camarillo, G., "Requirements for Session Initiation Protocol [7] Olson, S., "REFER extensions",
(SIP) Exploder Invocation", draft-camarillo-sipping-exploders-02 draft-olson-sipping-refer-extensions-02 (work in progress), July
(work in progress), February 2004. 2004.
10.2 Informational References [8] Camarillo, G., "Requirements and Framework for Session
Initiation Protocol (SIP)Uniform Resource Identifier (URI)-List
Services", draft-ietf-sipping-uri-services-00 (work in
progress), July 2004.
[10] Rosenberg, J. and H. Schulzrinne, "A Session Initiation 12.2 Informational References
Protocol (SIP) Event Package for Conference State",
draft-ietf-sipping-conference-package-03 (work in progress),
February 2004.
[11] Camarillo, G., "A Transaction Event Package for the Session [9] Rosenberg, J. and H. Schulzrinne, "A Session Initiation Protocol
Initiation Protocol (SIP)", (SIP) Event Package for Conference State",
draft-camarillo-sipping-transac-package-00 (work in progress), draft-ietf-sipping-conference-package-05 (work in progress),
February 2004. July 2004.
Authors' Addresses Authors' Addresses
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
skipping to change at page 10, line 13 skipping to change at page 12, line 13
EMail: miguel.an.garcia@nokia.com EMail: miguel.an.garcia@nokia.com
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the IETF's procedures with respect to rights in IETF Documents can on the procedures with respect to rights in RFC documents can be
be found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
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