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rfc:rfc5263

Network Working Group M. Lonnfors Request for Comments: 5263 J. Costa-Requena Category: Standards Track E. Leppanen

                                                                 Nokia
                                                          H. Khartabil
                                                              Ericsson
                                                        September 2008
          Session Initiation Protocol (SIP) Extension for
            Partial Notification of Presence Information

Status of This Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Abstract

 By default, presence delivered using the presence event package for
 the Session Initiation Protocol (SIP) is represented in the Presence
 Information Data Format (PIDF).  A PIDF document contains a set of
 elements, each representing a different aspect of the presence being
 reported.  When any subset of the elements change, even just a single
 element, a new document containing the full set of elements is
 delivered.  This memo defines an extension allowing delivery of only
 the presence data that has actually changed.

Lonnfors, et al. Standards Track [Page 1] RFC 5263 Partial Notification September 2008

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
 2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  3
 3.  Introduction to the Partial Notification Mechanism . . . . . .  3
   3.1.  Basic Presence Agent Operation . . . . . . . . . . . . . .  3
   3.2.  Operation with Partial Notification  . . . . . . . . . . .  3
 4.  Client and Server Operations . . . . . . . . . . . . . . . . .  4
   4.1.  Content-Type for Partial Notifications . . . . . . . . . .  4
   4.2.  Watcher Generation of SUBSCRIBE Requests . . . . . . . . .  4
   4.3.  Presence Agent Processing of SUBSCRIBE Requests  . . . . .  4
   4.4.  Presence Agent Generation of Partial Notifications . . . .  5
   4.5.  Watcher Processing of NOTIFY Requests  . . . . . . . . . .  6
 5.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . .  7
 6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
 7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
 8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
   8.1.  Normative References . . . . . . . . . . . . . . . . . . . 14
   8.2.  Informative References . . . . . . . . . . . . . . . . . . 14

1. Introduction

 A presence event package for Session Initiation Protocol (SIP) [3]
 allows users ('watchers') to subscribe to other users'
 ('presentities') presence information.  The presence information is
 composed of multiple pieces of data that are delivered to the
 watcher.  The size of the presence information document can be large
 (i.e., the presence document can contain an arbitrary number of
 elements called presence tuples that convey data).  As specified in
 RFC 2778 [9] and the presence event package for SIP [3], a Presence
 Agent (PA) always delivers in presence notifications all the presence
 data that has been authorized for a certain watcher.  This is done
 regardless of what presence data has changed compared to last
 notification.  It may not be reasonable to send the complete presence
 information over low bandwidth and high latency links when only part
 of the presence information has actually changed.  This may end up
 degrading the presence service and causing bad perception at the
 watcher side.
 This document defines a partial notification approach where the
 presence server delivers to the watchers only those parts of the
 presence information that have changed compared to the presence
 information sent in the previous notifications.  This reduces the
 amount of data that is transported over the network.
 This mechanism utilizes the presence event package for SIP [3] and a
 new MIME type for carrying partial Presence Information Data Format
 documents [2].

Lonnfors, et al. Standards Track [Page 2] RFC 5263 Partial Notification September 2008

2. Conventions

 In this document, the key words "MUST", "MUST NOT", "REQUIRED",
 "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
 and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
 indicate requirement levels for compliant implementations.
 This document makes use of the vocabulary defined in RFC 2778 [9],
 RFC 3265 [6], the presence event package for SIP [3], and the PIDF
 extension for Partial Presence [2].

3. Introduction to the Partial Notification Mechanism

 This chapter briefly introduces the regular functionality of the
 presence service, and gives an overview of the partial notification
 solution.  This section is informational in nature.  It does not
 contain any normative statements.

3.1. Basic Presence Agent Operation

 The presence service normally operates so that a watcher sends a SIP
 SUBSCRIBE request targeted to the presentity.  The request is routed
 to the presence agent where the presentity's presence information is
 stored.  The SUBSCRIBE request can include an Accept header field
 that indicates the supported content types.
 The presence agent receives the SUBSCRIBE request and if there is no
 Accept header indicating the supported content types or the Accept
 header contains the default PIDF content type, the PA will generate
 presence notifications using the default PIDF format [5].  The PIDF
 document can contain one or multiple XML elements.  The PIDF document
 includes a set of elements defined in RFC 2778 [9], and its
 extensions for representing the presence information.  This PIDF
 document will be carried in the body of a NOTIFY request constructed
 as per RFC 3265 [6].  During basic operation, the presence document
 always contains the full state corresponding to the presence status
 of the presentity, as determined by the PA local policy and
 authorization rules.

3.2. Operation with Partial Notification

 The partial notification mechanism allows a watcher to request that,
 whenever possible, notifications contain only presence information
 that has actually changed.  A watcher that wants to receive partial
 notifications according to this document, creates a SIP SUBSCRIBE
 request similar to that of a regular presence subscription.  However,
 the SIP SUBSCRIBE request contains an Accept header field whose value

Lonnfors, et al. Standards Track [Page 3] RFC 5263 Partial Notification September 2008

 contains the "application/pidf-diff+xml" tag as well as the
 "application/pidf+xml" tag.
 When the presence agent receives the subscription, it examines the
 Accept header field value and if the "application/pidf-diff+xml"
 value is present, it can decide to use the partial notifications
 mechanism specified in this memo.  The presence agent builds NOTIFY
 requests that contain the Content-Type header field set to
 "application/pidf-diff+xml".  The first NOTIFY request that contains
 presence information will contain a full presence document.
 Subsequent NOTIFY requests can contain partial presence documents.
 This behavior is described in detail in Section 4.

4. Client and Server Operations

 Unless otherwise specified in this document, the regular watcher and
 presence agent behavior is applied as defined in the SIP presence
 event package [3].

4.1. Content-Type for Partial Notifications

 Entities supporting the partial notification extension described in
 this document MUST support the 'application/pidf-diff+xml' content
 type specified in the PIDF extension for partial presence [2].

4.2. Watcher Generation of SUBSCRIBE Requests

 A SUBSCRIBE request can be used to negotiate the preferred content
 type to be used in the notifications.  The Accept header field is
 used for this purpose as specified in RFC 3261 [4].  When a watcher
 wants to allow the presence agent to send partial notifications the
 watcher MUST include an Accept header field in its SUBSCRIBE request.
 The value of the Accept header field MUST contain 'application/
 pidf-diff+xml' (in addition to 'application/pidf+xml' required by the
 SIP presence event package [3]).  The watcher MAY include a "q"
 parameter with each Accept value to indicate the relative preference
 of that value.

4.3. Presence Agent Processing of SUBSCRIBE Requests

 The presence agent receives subscriptions from watchers and generates
 notifications according to the SIP presence event package [3].  If
 the watcher has indicated the supported content types in the Accept
 header field of the SUBSCRIBE request, the presence agent compares
 the values included in the Accept header field with the supported
 ones, and decides which one to use.  If the watcher has indicated
 preferred accept values by means of "q" parameters, the presence

Lonnfors, et al. Standards Track [Page 4] RFC 5263 Partial Notification September 2008

 agent SHOULD base the decision on those preferences, unless otherwise
 indicated by the presence agent local policy.

4.4. Presence Agent Generation of Partial Notifications

 Once a subscription is accepted and installed, the PA MUST deliver
 the full state of the presence information in the first partial
 notification that contains a presence document having <pidf-full>
 root element.  If the presence agent decides to send notifications
 that include a presence document according to this specification, the
 presence agent MUST build a presence document according to the PIDF
 extension for Partial Presence [2] and MUST set the Content-Type
 header field to the value 'application/pidf-diff+xml'.
 When using the 'application/pidf-diff+xml' MIME type, the PA MUST
 include a "version" attribute; for the first partial notification
 (within a given subscription), the PA MUST initialize version to
 value one (1).  This version counter is scoped to the subscription,
 and is incremented by one within each partial notification.  The
 version value is only reset when the given subscription is
 terminated.  It is not reset when the subscription is refreshed.
 When the PA generates a partial presence document, the PA SHOULD
 include only that presence information that has changed compared to
 the previous notifications.  It is up to the PA's local policy to
 determine what is considered as a change to the previous state.
 The PA MUST construct the partial presence document according to the
 following logic:
 o  The PA MUST construct the presence information according to the
    PIDF extension for Partial Presence [2].  All the information that
    has been added to the presence document is listed inside <add>
    elements.  All information that has been removed from the presence
    document is listed inside <remove> elements, and all information
    that has been changed is listed under <replace> elements.
 o  The PA MUST include a "version" attribute in the presence
    document.  The PA MUST increment the version number by one
    compared to the earlier successfully sent presence document in the
    PIDF extension for Partial Presence [2] format to the watcher
    associated with a certain subscription.
 The PA MUST NOT send a new NOTIFY request that contains a partial
 notification for the same Request-URI until it has received a final
 response from the watcher for the previous one or the previous NOTIFY
 request has timed out.

Lonnfors, et al. Standards Track [Page 5] RFC 5263 Partial Notification September 2008

 When the PA receives a SUBSCRIBE request (refresh or termination)
 within the associated subscription, it SHOULD send a NOTIFY request
 containing the full presence document.
 If the PA has used other than the 'application/pidf-diff+xml' content
 type in notifications within the existing subscription, and changes
 to deliver partial notifications, the PA MUST deliver the full state
 of the presence information containing a presence document having
 <pidf-full> root element as the first partial notification.

4.5. Watcher Processing of NOTIFY Requests

 Watcher processes all NOTIFY requests that contain 'application/
 pidf+xml' content type as specified in RFC 3856 [3].
 When the watcher receives the first notification containing the
 'application/pidf-diff+xml' MIME body the watcher MUST initialize an
 internal version counter, related to this subscription, to the value
 of the "version" included in the presence document.  This version
 counter is scoped to the subscription.  The watcher MUST also store
 the received full presence document as its local copy.
 When the watcher receives a subsequent 'application/pidf-diff+xml'
 encoded presence document the watcher MUST compare the received
 "version" attribute with the local version counter.  If the watcher
 receives a presence document with the "version" attribute value equal
 or lower than the locally stored version number, it is considered a
 PA failure, and the watcher SHOULD discard the document without
 further processing.  Otherwise, the watcher MUST modify its locally
 stored information according to the following logic:
 o  If the root element of the presence document is <pidf-full>, the
    watcher must replace its local copy of the presence document with
    the presence document received in the 'application/pidf-diff+xml'
    body and set the internal version value to the value of the
    "version" attribute included in the presence document.
 o  If the root element of the presence document is <pidf-diff> and
    the received version number is incremented by one compared with
    the local version counter, the watcher MUST apply the changes to
    its local copy of the full presence document indicated in the
    received 'application/pidf-diff+xml' document as specified in PIDF
    extension for Partial Presence [2].  The watcher MUST increment
    the local version counter by one.

Lonnfors, et al. Standards Track [Page 6] RFC 5263 Partial Notification September 2008

 o  If the root element of the presence document is <pidf-diff> and
    the received "version" value is higher by more than one compared
    with the locally stored value, the watcher assumes that one or
    more NOTIFYs were lost.  The watcher SHOULD either refresh the
    subscription in order to receive a full presence document or
    terminate the subscription.
 If the watcher encounters a processing error while processing the
 received 'application/pidf-diff+xml' encoded presence document, look
 at Section 5.1 of [8].  In this case, the watcher SHOULD renew the
 subscription.  The watcher MAY also fall back to normal presence
 operations by not inserting 'application/pidf-diff+xml' in a new
 SUBSCRIBE request.  It is hardly reasonable to signal this error to
 the notifier even if the error exists in the notifier process.
 If the PA changes the content type used in notifications within the
 existing subscription, the watcher MUST discard all the previously
 received presence information (except local version counter) from
 that particular presentity and process the new content as specified
 for that content type.  The local version counter MUST NOT be
 discarded because if the PA changes back to 'application/
 pidf-diff+xml', the MIME type version counter will continue to
 increase from the last version value.

5. Examples

 The following message flow shows an example applying the partial
 notifications mechanism.
 A watcher sends a SUBSCRIBE request declaring support for the default
 presence format ('application/pidf+xml) and for the partial
 notification format ('application/pidf-diff+xml') in the Accept
 header field value.  The watcher uses the "q" parameter to set the
 preference for receiving partial notifications.  The PA accepts the
 subscription and, based on the "q" parameter value, selects to send
 partial notifications in NOTIFY requests.  The first NOTIFY request
 includes the full state of presence information.  The following
 notifications only include information about delta of the presence
 information from the previous NOTIFY requests.

Lonnfors, et al. Standards Track [Page 7] RFC 5263 Partial Notification September 2008

     Watcher                   Presence Agent                  PUA
          | F1 SUBSCRIBE              |                         |
          |-------------------------->|                         |
          | F2 200 OK                 |                         |
          |<--------------------------|                         |
          | F3 NOTIFY                 |                         |
          |<--------------------------|                         |
          | F4 200 OK                 |                         |
          |-------------------------->|                         |
          |                           |                         |
          |                           |   Update presence       |
          |                           |<----------------------- |
          |                           |                         |
          | F5 NOTIFY                 |                         |
          |<--------------------------|                         |
          | F6 200 OK                 |                         |
          |-------------------------->|                         |
       Message Details
    F1 SUBSCRIBE   watcher->example.com server
          SUBSCRIBE sip:resource@example.com SIP/2.0
          Via: SIP/2.0/TCP watcherhost.example.com;
            branch=z9hG4bKnashds7
          To: <sip:resource@example.com>
          From: <sip:watcher@example.com> ;tag=xfg9
          Call-ID: 2010@watcherhost.example.com
          CSeq: 17766 SUBSCRIBE
          Max-Forwards: 70
          Event: presence
          Accept: application/pidf+xml;q=0.3,
            application/pidf-diff+xml;q=1
          Contact: <sip:user@watcherhost.example.com>
          Expires: 3600
          Content-Length: 0

Lonnfors, et al. Standards Track [Page 8] RFC 5263 Partial Notification September 2008

    The PA accepts the subscription and generates a 200 OK response
    to the SUBSCRIBE request
       F2 200 OK   example.com server ->watcher
          SIP/2.0 200 OK
          Via: SIP/2.0/TCP watcherhost.example.com;
            branch=z9hG4bKnashds7
            ;received=192.0.2.1
          To: <sip:resource@example.com>;tag=ffd2
          From: <sip:watcher@example.com>;tag=xfg9
          Call-ID: 2010@watcherhost.example.com
          CSeq: 17766 SUBSCRIBE
          Event: presence
          Expires: 3600
          Contact: <sip:server.example.com>
          Content-Length: 0
    The PA, based on the "q" parameter value in the Accept header
    of the SUBSCRIBE request (F1), decides to use partial
    notifications.  The PA creates the first NOTIFY request that
    includes the full presence document.
       F3 NOTIFY  example.com server -> watcher
          NOTIFY sip:user@watcherhost.example.com SIP/2.0
          Via: SIP/2.0/TCP server.example.com;
            branch=z9hG4bKna998sk
          To: <sip:watcher@example.com>;tag=xfg9
          From: <sip:resource@example.com>;tag=ffd2
          Call-ID: 2010@watcherhost.example.com
          Event: presence
          Subscription-State: active;expires=3599
          Max-Forwards: 70
          CSeq: 8775 NOTIFY
          Contact: <sip:server.example.com>
          Content-Type: application/pidf-diff+xml
          Content-Length: ...
 <?xml version="1.0" encoding="UTF-8"?>
    <p:pidf-full xmlns="urn:ietf:params:xml:ns:pidf"
           xmlns:p="urn:ietf:params:xml:ns:pidf-diff"
           xmlns:r="urn:ietf:params:xml:ns:pidf:rpid"
           xmlns:c="urn:ietf:params:xml:ns:pidf:caps"
           xmlns:cp="urn:ietf:params:xml:ns:pidf:cipid"
           xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
           entity="sip:resource@example.com"
           version="1">

Lonnfors, et al. Standards Track [Page 9] RFC 5263 Partial Notification September 2008

     <tuple id="sg89ae">
      <status>
       <basic>open</basic>
      </status>
      <c:servcaps>
       <c:audio>true</c:audio>
       <c:video>false</c:video>
       <c:message>true</c:message>
      </c:servcaps>
       <r:relationship><r:assistant/></r:relationship>
      <contact priority="0.8">tel:09012345678</contact>
     </tuple>
     <tuple id="cg231jcr">
      <status>
       <basic>open</basic>
      </status>
      <contact priority="1.0">im:res@example.com</contact>
     </tuple>
     <tuple id="r1230d">
      <status>
       <basic>closed</basic>
      </status>
      <cp:homepage>http://example.com/~res/</cp:homepage>
      <cp:icon>http://example.com/~res/icon.gif</cp:icon>
      <cp:card>http://example.com/~res/card.vcd</cp:card>
      <contact priority="0.9">sip:resource@example.com</contact>
     </tuple>
     <note xml:lang="en">Full state presence document</note>
     <dm:person id="fdkfj">
       <r:activities>
        <r:on-the-phone/>
        <r:busy/>
       </r:activities>
     </dm:person>

Lonnfors, et al. Standards Track [Page 10] RFC 5263 Partial Notification September 2008

     <dm:device id="u00b40c7">
       <c:devcaps>
        <c:mobility>
         <c:supported>
          <c:mobile/>
         </c:supported>
        </c:mobility>
       </c:devcaps>
       <dm:deviceID>mac:xxx</dm:deviceID>
     </dm:device>
    </p:pidf-full>
       F4 200 OK watcher -> example.com server
          SIP/2.0 200 OK
          Via: SIP/2.0/TCP server.example.com;
            branch=z9hG4bKna998sk
            ;received=192.0.2.2
          To: <sip:watcher@example.com>;tag=xfg9
          From: <sip:resource@example.com>;tag=ffd2
          Call-ID: 2010@watcherhost.example.com
          CSeq: 8775 NOTIFY
          Content-Length: 0
          At a later time, the presentity's presence information
          changes.  The PA generates a NOTIFY request
          that includes information about the changes.
    F5 NOTIFY example.com server -> watcher
          NOTIFY sip:user@watcherhost.example.com SIP/2.0
          Via: SIP/2.0/TCP server.example.com;
            branch=z9hG4bKna998sl
          To: <sip:watcher@example.com>;tag=xfg9
          From: <sip:resource@example.com>;tag=ffd2
          Call-ID: 2010@watcherhost.example.com
          CSeq: 8776 NOTIFY
          Event: presence
          Subscription-State: active;expires=3543
          Max-Forwards: 70
          Contact: <sip:server.example.com>
          Content-Type: application/pidf-diff+xml
          Content-Length: ...

Lonnfors, et al. Standards Track [Page 11] RFC 5263 Partial Notification September 2008

    <?xml version="1.0" encoding="UTF-8"?>
    <p:pidf-diff xmlns="urn:ietf:params:xml:ns:pidf"
                 xmlns:p="urn:ietf:params:xml:ns:pidf-diff"
                 xmlns:r="urn:ietf:params:xml:ns:pidf:rpid"
                 xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
              entity="sip:resource@example.com"
              version="2">
     <p:add sel="presence/note" pos="before"><tuple id="ert4773">
      <status>
       <basic>open</basic>
      </status>
      <contact priority="0.4">mailto:res@example.com</contact>
      <note xml:lang="en">This is a new tuple inserted
            between the last tuple and note element</note>
     </tuple>
     </p:add>
     <p:replace sel="*/tuple[@id='r1230d']/status/basic/text()"
      >open</p:replace>
     <p:remove sel="*/dm:person/r:activities/r:busy"/>
     <p:replace sel="*/tuple[@id='cg231jcr']/contact/@priority"
      >0.7</p:replace>
    </p:pidf-diff>
    F6 200 OK watcher-> example.com server
          SIP/2.0 200 OK
          Via: SIP/2.0/TCP server.example.com;
            branch=z9hG4bKna998sl
           ;received=192.0.2.2
          To: <sip:watcher@example.com>;tag=xfg9
          From: <sip:resource@example.com>;tag=ffd2
          Call-ID: 2010@watcherhost.example.com
          CSeq: 8776 NOTIFY
          Content-Length: 0

Lonnfors, et al. Standards Track [Page 12] RFC 5263 Partial Notification September 2008

6. Security Considerations

 This specification relies on the presence event package for SIP [3].
 Partial notifications can reveal information about what has changed
 compared to the previous notification.  This can make it easier for
 an eavesdropper to know what kind of changes are happening in the
 presentity's presence information.  However, the same information can
 be found if the presence event package is used with baseline PIDF
 [5].
 A third party can inject a NOTIFY request with partial state that
 will cause the watcher to think it has missed a partial notification
 and to request a new full presence document.  This is no worse than
 what we have without this extension since a party that could perform
 such action could also send a NOTIFY with Subscription-State:
 terminated and achieve the same effect without knowing about the
 extension.  Partial Notification does not make the situation any
 worse, and the protection mechanisms from the existing system apply
 to preventing this attack against the partial notification mechanism.
 Presence-related security considerations are extensively discussed in
 the presence event package for SIP [3] and all those identified
 security considerations apply to this document as well.  Issues
 described in the presence event package for SIP [3], including
 confidentiality, message integrity and authenticity, outbound
 authentication, replay prevention, Denial-of-Service (DoS) attacks
 against thirst parties and DoS attacks against servers all apply here
 without any change.
 It is RECOMMENDED that TLS [7] be used between elements to provide
 hop-by-hop confidentially protection.  Furthermore, S/MIME MAY be
 used for integrity and authenticity of SUBSCRIBE and NOTIFY requests.
 This is described in Section 23 of RFC 3261.

7. Acknowledgments

 The authors would like to thank Jari Urpalainen, Jyrki Aarnos,
 Jonathan Rosenberg, Dean Willis, Kriztian Kiss, Juha Kalliokulju,
 Miguel Garcia, Anders Kristensen, Yannis Pavlidis, Ben Cambell,
 Robert Sparks, and Tim Moran for their valuable comments.

Lonnfors, et al. Standards Track [Page 13] RFC 5263 Partial Notification September 2008

8. References

8.1. Normative References

 [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", BCP 14, RFC 2119, March 1997.
 [2]  Lonnfors, M., Khartabil, H., Leppanen, E., and J. Urpalainen,
      "Presence Information Data Format (PIDF) Extension for Partial
      Presence", RFC 5262, August 008.
 [3]  Rosenberg, J., "A Presence Event Package for the Session
      Initiation Protocol (SIP)", RFC 3856, August 2004.
 [4]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
      Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
      Session Initiation Protocol", RFC 3261, June 2002.
 [5]  Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr, W., and
      J. Peterson, "Presence Information Data Format (PIDF)",
      RFC 3863, August 2004.
 [6]  Roach, A., "SIP-Specific Event Notification", RFC 3265,
      June 2002.
 [7]  Dierks, T. and E. Rescorla, "The TLS Protocol Version 1.1",
      RFC 4346, April 2006.
 [8]  Urpalainen, J., "An Extensible Markup Language (XML) Patch
      Operations Framework Utilizing XML Path Language (XPath)
      Selectors", RFC 5261, September 2008.

8.2. Informative References

 [9]  Day, M., Rosenberg, J., and H. Sugano, "A Model for Presence and
      Instant Messaging", RFC 2778, February 2000.

Lonnfors, et al. Standards Track [Page 14] RFC 5263 Partial Notification September 2008

Authors' Addresses

 Mikko Lonnfors
 Nokia
 P.O. Box 321
 Helsinki
 Finland
 Phone: +358 71 8008000
 EMail: mikko.lonnfors@nokia.com
 Jose Costa-Requena
 Nokia
 P.O. Box 321
 Helsinki
 Finland
 Phone: +358 71 8008000
 EMail: jose.costa-requena@nokia.com
 Eva Leppanen
 Nokia
 Lempaala
 Finland
 EMail: eva.leppanen@saunalahti.fi
 Hisham Khartabil
 Ericsson
 Melbourne
 Australia
 Phone: +61 416 108 890
 EMail: hisham.khartabil@gmail.com

Lonnfors, et al. Standards Track [Page 15] RFC 5263 Partial Notification September 2008

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 Copies of IPR disclosures made to the IETF Secretariat and any
 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
 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.

Lonnfors, et al. Standards Track [Page 16]

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