SIPPING Working Group A. Johnston Internet-Draft H. Sinnreich Expires: January 16, 2005 MCI A. Clark Telchemy Incorporated A. Pendleton Nortel Networks July 18, 2004 RTCP Summary Report Delivery to Third Parties draft-johnston-sipping-rtcp-summary-03 Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 16, 2005. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document discusses the motivation and requirements for the delivery of RTCP extended reports and other summary reports from VoIP applications in endpoints to non-participants in the session. A Johnston, et al. Expires January 16, 2005 [Page 1] Internet-Draft RTCP Summary Delivery July 2004 publication mechanism using a new SIP events package is proposed as a solution. An event package "perfrpt" and an application/rtcp-xr MIME type is defined in this document along with some example call flows. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Motivations for the Approach . . . . . . . . . . . . . . . . . 4 4. Why SNMP is Not Appropriate . . . . . . . . . . . . . . . . . 4 5. SIP Events Approach . . . . . . . . . . . . . . . . . . . . . 4 6. Event Package Formal Definition . . . . . . . . . . . . . . . 5 6.1 Event Package Name . . . . . . . . . . . . . . . . . . . . 5 6.2 Event Package Parameters . . . . . . . . . . . . . . . . . 5 6.3 SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . 5 6.4 Subscription Duration . . . . . . . . . . . . . . . . . . 5 6.5 NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . 5 6.6 Metric Definitions . . . . . . . . . . . . . . . . . . . . 7 6.7 Use of PUBLISH Method . . . . . . . . . . . . . . . . . . 9 6.8 Examples . . . . . . . . . . . . . . . . . . . . . . . . . 10 7. Call Flow Examples . . . . . . . . . . . . . . . . . . . . . . 12 7.1 End of Session Notification Call Flow . . . . . . . . . . 12 7.2 Mid Session Report . . . . . . . . . . . . . . . . . . . . 13 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8.1 SIP Event Package Registration . . . . . . . . . . . . . . 14 8.2 application/rtcp-xr MIME Registration . . . . . . . . . . 15 9. Security Considerations . . . . . . . . . . . . . . . . . . . 15 10. Updates since -02 . . . . . . . . . . . . . . . . . . . . . 16 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 12. Informative References . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 17 Intellectual Property and Copyright Statements . . . . . . . . 18 Johnston, et al. Expires January 16, 2005 [Page 2] Internet-Draft RTCP Summary Delivery July 2004 1. Introduction There is a general need for real-time reporting of session quality in enterprise and service provider networks. While the approach discussed in this document is quite general, this document is limited in scope to the delivery of particular RTCP summary reports. RTP Control Protocol (RTCP) [3] defines Sender Reports (SR) and Receiver Reports (RR) which are exchanged between the participants in a media session about the quality of the media session. RTCP Extended Reports (XR) [4] have also been defined to provide additional quality information. In particular, two summary reports are included: a statistics summary report and a VoIP (Voice over IP) metrics block. This summary information is of particular interest to certain parties who may not be participants in the media session. For example, a service provider might be interested in logging a summary report of the QoS of a VoIP session. Alternatively, an enterprise might want to compile a summary of the QoS of multimedia sessions established over a wide area network. In the case of a gateway or other high-density device, the device is likely to implement various AAA protocols and have the ability to log and export this type of RTCP summary reports. However, this is not practical in smaller endpoints such as SIP phones, clients, or mobile phones. This document discusses the requirements and a mechanism to allow a third party which is not a participant in a session receive RTCP summary reports. 2. Requirements REQ-1: An authorized third party should be able to receive selected RTCP reports on a near real time basis. REQ-2: The VoIP application should not have to store large amounts of information. REQ-3: The VoIP application must be able to authenticate the third party. REQ-4: The RTCP report information must be able to be transferred securely. REQ-5: A VoIP application participating in a bi-directional session will store and send RTCP summary reports for both directions. Johnston, et al. Expires January 16, 2005 [Page 3] Internet-Draft RTCP Summary Delivery July 2004 REQ-6: The reports will include or be associated with dialog identifiers for correlation purposes. 3. Motivations for the Approach Monitor the application: While QoS monitoring in network elements using for example SNMP is quite common, only the VoIP applications in endpoints are close enough to the experience of individual users, on a call by call basis in endpoints as diverse as desktop SIP phones, PDAs, PCs or mobile phones. For this reason, the approach taken here is to monitor the voice quality at the application level and not in network elements. Focus on voice specific impairments: RTCP extensions support the monitoring of various impairments such as packet loss, delay and jitter, but more important, specific metrics are included to measure burst errors that produce voice clipping. Voice clipping is the most annoying impairment in VoIP due to network congestion in the media path between VoIP applications. 4. Why SNMP is Not Appropriate Since this type of QoS monitoring seems related to management, SNMP could possibly be used to collect this type of data as well. SNMP is however primarily used for management of network devices as they relate to the infrastructure but is not typically used for management of applications on that infrastructure. The focus of SIP is applications and the performance management for those applications cannot rely on SNMP. SNMP may be used to manage some aspects of the physical device aspects of the SIP user agent Specifically, SNMP may be used to manage the SIP user agent - the phone, soft phone or gateway. However, the information available in RTCP summary reports is of less interest to the management of the UA and more of interest to the VoIP service provider. In many cases, separate entities will be involved. For example, an enterprise may manage their own SIP phones using SNMP, but a service provider provides SIP and gateway services. It is unlikely a service provider will have SNMP privileges and may not be able to manage NAT/firewall traversal, etc. For these reasons, SNMP is not a good fit for this "service level" management function. 5. SIP Events Approach In this approach, a new SIP events package [6] is be defined. The intended method to use for this event is PUBLISH [8], though it could Johnston, et al. Expires January 16, 2005 [Page 4] Internet-Draft RTCP Summary Delivery July 2004 also be used with SUBSCRIBE and NOTIFY. A VoIP application will PUBLISH performance data to a State Agent which will make the information available to other applications. 6. Event Package Formal Definition 6.1 Event Package Name This document defines a SIP Event Package as defined in RFC 3265 [2]. The event-package token name for this package is: "perfrpt" 6.2 Event Package Parameters No event package parameters are defined. 6.3 SUBSCRIBE Bodies No SUBSCRIBE bodies are described by this specification. 6.4 Subscription Duration Subscriptions to this event package MAY range from minutes to weeks. Subscriptions in hours or days are more typical and are RECOMMENDED. The default subscription duration for this event package is one hour. 6.5 NOTIFY Bodies There are two notify bodies: a general report and a threshold report. The general report is used for periodic, mid-call reporting and end of call reporting. The general report can include both local and remote metrics. The threshold report is used when call quality degrades. The general report is also included in the alert report to provide all of the necessary diagnostic information. This specification defines a new MIME type application/rtcp-xr which is a text encoding of the RTCP-XR statistics, with the addition of a few additional identifiers. The following syntax specification uses the augmented Backus-Naur Form (BNF) as described in RFC-2234 [7]. General Report Event: Johnston, et al. Expires January 16, 2005 [Page 5] Internet-Draft RTCP Summary Delivery July 2004 VQEvent = LocalMetrics CLRF RemoteMetrics LocalMetrics = ("LocalMetrics") HCOLON VoiceQualityMetrics RemoteMetrics = ("RemoteMetrics") HCOLON VoiceQualityMetrics VoiceQualityMetrics = ("VQMetrics") HCOLON CLRF CodecInfo CRLF JitterBufferInfo CRLF PacketLossMetrics CRLF BurstMetrics CLRF GapMetrics CLRF DelayMetrics CLRF SignalMetrics CLRF QualityScores CLRF CodecInfo = ("codec") EQUALS c-type SPACE packet-rate SPACE pl-conceal c-type = ("type") HCOLON HEX (HH) packet-rate = ("prate") HCOLON HEX (HH) pl-conceal = ("plc") HCOLON ("std" | "enh" | "unk") JitterBufferInfo = ("jb") EQUALS jb-type SPACE jb-rate SPACE jb-nominal SPACE jb-max SPACE jb-abs-max jb-type = ("type") HCOLON ("adapt" | "non-adapt" | "unknown") jb-rate = ("rate") HCOLON HEX (HHH) jb-max = ("max") HCOLON HEX (HHH) jb-nominal = ("nom") HCOLON HEX (HHH) jb-absmax = ("abmax") HCOLON HEX (HHH) PacketLossMetrics = ("pl") EQUALS loss-rate SPACE discard-rate loss-rate = ("loss") HCOLON HEX (HH) discard-rate = ("disc") HCOLON HEX (HH) BurstMetrics = ("burst") EQUALS density SPACE length GapMetrics = ("gap") EQUALS density SPACE length density = ("den") HCOLON HEX (HH) length = ("len") HCOLON HEX (HHHH) DelayMetrics = ("delay") EQUALS round-trip SPACE end-system round-trip = ("rt") COLON HEX (HHHH) end-system = ("es") COLON HEX (HHHH) SignalMetrics = ("signal") EQUALS signal SPACE echo-return-loss SPACE noise Johnston, et al. Expires January 16, 2005 [Page 6] Internet-Draft RTCP Summary Delivery July 2004 signal = ("sig") HCOLON HEX (HH) echo-return-loss = ("erl") HCOLON HEX (HH) noise = ("n") HCOLON HEX (HH) QualityScores = ("qs") EQUALS r-lq SPACE r-cg SPACE mos-lq SPACE mos-cq r-lq = ("r-lq") HCOLON HEX (HH) r-cq = ("r-cg") HCOLON HEX (HH) mos-lq = ("m-lq") HCOLON HEX (H"."H) mos-cq = ("m-cq") HCOLON HEX (H"."H) DialogID = ("DialogID") HCOLON callid *(SEMI dialogid-param) dialogid-param = to-tag / from-tag / generic-param callid = token to-tag = "to-tag" EQUAL token from-tag = "from-tag" EQUAL token Alert Format: VoiceQualityAlert = ("VQAlert") HCOLON SPACE ViolationMetric SPACE Severity CRLF VoiceQualityMetrics ViolationMetric = ("Type") HCOLON ("r-lq" / "r-cq" / "burst" / "erl" / "delay" / token ) Severity = ("Severity") HCOLON ("Warning" | "Critical" | "Clear") 6.6 Metric Definitions Codec Type The IANA defined audio codec value. Packetization Rate The rate, in milliseconds, at which the source audio is sampled. See RFC 3611 [4] for a full description of these metrics. Packet Loss Concealment Indicator of whether packet loss concealment is used. When PLC = "std", or standard, then a simple replay or interpolation algorithm is being used to fill-in the missing packet; this approach is typically able to conceal isolated lost packets at low packet loss rates. When PLC = "enh", or enhanced, then an enhanced interpolation algorithm is being used; algorithms of this type are able to conceal high packet loss rates effectively. When PLC = "unk", then no information is available Johnston, et al. Expires January 16, 2005 [Page 7] Internet-Draft RTCP Summary Delivery July 2004 concerning the use of PLC; however, for some codecs this may be inferred. Jitter Buffer Type Indicator of the jitter buffer is adaptive or static. When the jitter buffer is adaptive, then its size is being dynamically adjusted to deal with varying levels of jitter. When non- adaptive, the jitter buffer size is maintained at a fixed level. Jitter Buffer Rate This represents the implementation specific adjustment rate of a jitter buffer in adaptive mode. Jitter Buffer Nomimal Delay This is the current nominal jitter buffer delay in milliseconds, which corresponds to the nominal jitter buffer delay for packets that arrive exactly on time. This parameter MUST be provided for both fixed and adaptive jitter buffer implementations. Jitter Buffer Maximum Delay This is the current maximum jitter buffer delay in milliseconds which corresponds to the earliest arriving packet that would not be discarded. In simple queue implementations this may correspond to the nominal size. In adaptive jitter buffer implementations, this value may dynamically vary up to JB abs max (see below). Jitter Buffer Absolute Maximum Delay This is the absolute maximum delay in milliseconds that the adaptive jitter buffer can reach under worst case conditions. If this value exceeds 65535 milliseconds, then this field SHALL convey the value 65535. This parameter MUST be provided for adaptive jitter buffer implementations and its value MUST be set to JB maximum for fixed jitter buffer implementations. Packet Loss Ratio The fraction of packets lost within the network. Packet Discard Rate The fraction of packets discarded due to jitter Burst Density The fraction of packets lost and discarded within a burst (high loss rate) period. Burst Length (mS) The mean length of a burst. Johnston, et al. Expires January 16, 2005 [Page 8] Internet-Draft RTCP Summary Delivery July 2004 Gap Density The fraction of packets lost and discarded within a gap (low loss rate) period. Gap Length (mS) The mean length of a gap Round Trip Delay (mS) The round trip delay between RTP interfaces End System Round Trip Delay (mS) The "round trip" delay between the RTP interface and the analog or trunk interface. Signal Level (dBm) The signal level during talkspurts. Noise Level (dBm) The signal level during silence periods. Residual Echo Return Loss (dB) The residual (uncancelled) echo level from the analog or trunk interface. R - Listening Quality Estimated listening call quality expressed in a score from 0 - 100, per ITU-T standard G.107. R - Conversational Quality Estimated conversational call quality expressed in a score from 0 - 100, per ITU-T standard G.107. MOS-LQ Estimated listening call quality expressed as a MOS score MOS-CQ Estimated conversational call quality expressed as a MOS score 6.7 Use of PUBLISH Method A VoIP application which supports this specification will publish performance report information using the PUBLISH method. An application wishing to access this performance data maintains a State Agent for the perfrpt event package. The Request-URI of the PUBLISH Johnston, et al. Expires January 16, 2005 [Page 9] Internet-Draft RTCP Summary Delivery July 2004 method is set to the AOR of the VoIP application. The PUBLISH method is sent to the normal default outbound proxy server of the VoIP application. The State Agent can use normal mechanisms for publication throttling or rejection of the information as described in the PUBLISH [8] specification. 6.8 Examples Call Alert Scenario PUBLISH sip:alice@chicago.example.com SIP/2.0 Via: SIP/2.0/UDP pc22.example.com;branch=z9hG4bK3343d7 Max-Forwards: 70 To: From: Alice ;tag=a3343df32 Call-ID: k3l43id034kevnx7334s CSeq: 4321 PUBLISH Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Event: perfrpt Accept: application/sdp, message/sipfrag Content-Type: application/rtcp-xr Content-Length: ... Event:perfrpt VQAlert: AlertType:r-lq Severity:Warning LocalMetrics:VQMetrics: codec=type:0 prate:20 plc:enh jb=type:adapt rate:2 nom:40 max:80 abmax:120 pl=loss:5 disc:2 burst=den:0 len:0 gap=den:2 len:0 delay=rt:200 es:140 signal=sig:2 rerl:14 n:1 qs=r-lq:82 r-cq:80 ml:3.4 mc:3.3 RemoteMetrics:VQMetrics: codec=type:0 prate:20 plc:std jb=type:adapt rate:2 nom:40 max:80 abmax:120 plm=loss:02 disc:01 burst=den:0 len:0 gap=den:2 len:0 delay=rt:100 es:140 signal=sig:2 rerl:14 n:1 qs=r-lq:81 r-cq:90 ml:3.1 mc:3.2 DialogID:38419823470834;to-tag=8472761;from-tag=9123dh311 Johnston, et al. Expires January 16, 2005 [Page 10] Internet-Draft RTCP Summary Delivery July 2004 This alert indicates that the quality of the call in progress has degraded to an unacceptable level. In this case, the packet loss rate was 5%, the packet discard rate (due to jitter) was 2%, there were no bursts, the gap loss/discard rate was 2%, the round trip delay was 160mS, the end system delay was 140mS, the R factor was 85, the MOS-LQ 3.6, the MOS-CQ 3.5. The remote metrics were available via RTCP XR [4 ] so they are also included in the event. End of Session Scenario PUBLISH sip:alice@chicago.example.com SIP/2.0 Via: SIP/2.0/UDP pc22.example.com;branch=z9hG4bK3343d7 Max-Forwards: 70 To: From: Alice ;tag=a3343df32 Call-ID: k3l43id034kevnx7334s CSeq: 4331 PUBLISH Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Event: perfrpt Accept: application/sdp, message/sipfrag Content-Type: application/rtcp-xr Content-Length: ... Event:perfrpt LocalMetrics:VQMetrics: codec=type:0 prate:20 plc:std jb=type:adapt rate:2 nom:40 max:80 abmax:120 pl=loss:05 disc:02 burst=den:0 len:0 gap=den:2 len:0 delay=rt:200 es:140 signal=sig:2 rerl:14 n:1 qs=r-lq:90 r-cq:80 ml:3.4 mc:3.3 RemoteMetrics:VQMetrics: codec=type:0 prate:20 plc:std jb=type:adapt rate:2 nom:40 max:80 abmax:120 pl=loss:02 disc:01 burst=den:0 len:0 gap=den:2 len:0 dly=rt:100 es:140 sig=sig:2 rerl:14 n:1 qs=r-lq:90 r-cq:90 ml:3.1 mc:3.2 DialogID:38419823470834;to-tag=8472761;from-tag=9123dh311 This event report provides the parameters as they were at the end of the session. Johnston, et al. Expires January 16, 2005 [Page 11] Internet-Draft RTCP Summary Delivery July 2004 7. Call Flow Examples This section shows a number of call flow examples showing how the event package works. 7.1 End of Session Notification Call Flow Alice Proxy/Registrar Collector Bob | | | | | | | | | REGISTER Allow-Event:perfrpt F1 | | |------------------->| | | | 200 OK F2 | | | |<-------------------| | | | INVITE F3 | | | |------------------->| | | | | INVITE F4 | | | |---------------------------------------->| | | 200 OK F5 | | | |<----------------------------------------| | 200 OK F6 | | | |<-------------------| | | | ACK F7 | | | |------------------->| | | | | ACK F8 | | | |---------------------------------------->| | RTP | | | |<============================================================>| | RTCP | | | |<============================================================>| | | | | | BYE F9 | | | |------------------->| BYE F10 | | | |---------------------------------------->| | | 200 OK F11 | | | |<----------------------------------------| | 200 OK F12 | | | |<-------------------| | | | PUBLISH Event:perfrpt F13 | | |------------------->| | | | | PUBLISH Event:perfrpt F14 | | |------------------->| | | | 200 OK F15 | | | |<-------------------| | | 200 OK F16 | | | |<-------------------| | | Figure 1. Summary report sent after session termination. Johnston, et al. Expires January 16, 2005 [Page 12] Internet-Draft RTCP Summary Delivery July 2004 7.2 Mid Session Report Alice Proxy/Registrar Collector Bob | | | | | INVITE F1 | | | |------------------->| | | | | INVITE F2 | | | |---------------------------------------->| | | 200 OK F3 | | | |<----------------------------------------| | 200 OK F4 | | | |<-------------------| | | | ACK F5 | | | |------------------->| | | | | ACK F6 | | | |---------------------------------------->| | RTP | | | |<============================================================>| | RTCP | | | |<============================================================>| | PUBLISH Event:perfrpt F7 | | |------------------->| | | | | PUBLISH Event:perfrpt F8 | | |------------------->| | | | 200 OK F9 | | | |<-------------------| | | 200 OK F10 | | | |<-------------------| | | | | | | | BYE F12 | | | |------------------->| BYE F13 | | | |---------------------------------------->| | | 200 OK F14 | | | |<----------------------------------------| | 200 OK F15 | | | |<-------------------| | | | PUBLISH Event:perfrpt F16 | | |------------------->| | | | | PUBLISH Event:perfrpt F17 | | |------------------->| | | | 200 OK F18 | | | |<-------------------| | | 200 OK F19 | | | |<-------------------| | | Figure 2. Summary report sent during session with threshold report. Johnston, et al. Expires January 16, 2005 [Page 13] Internet-Draft RTCP Summary Delivery July 2004 8. IANA Considerations This document registers a new SIP Event Package and a new MIME type. 8.1 SIP Event Package Registration Package name: perfrpt Type: package Contact: Alan Johnston Published Specification: This document Johnston, et al. Expires January 16, 2005 [Page 14] Internet-Draft RTCP Summary Delivery July 2004 8.2 application/rtcp-xr MIME Registration MIME media type name: application MIME subtype name: rtcp-xr Mandatory parameters: none Optional parameters: none Encoding considerations: text Security considerations: See next section. Interoperability considerations: none. Published specification: This document. Applications which use this media type: This document type is being used in notifications of VoIP quality reports. Additional Information: Magic Number: None File Extension: None Macintosh file type code: "TEXT" Personal and email address for further information: Alan Johnston Intended usage: COMMON Author/Change controller: The IETF. 9. Security Considerations RTCP reports can contain sensitive information since they can provide information about the nature and duration of a session established between two endpoints. As a result, any third party wishing to obtain this information should be properly authenticated and the information transferred securely. Johnston, et al. Expires January 16, 2005 [Page 15] Internet-Draft RTCP Summary Delivery July 2004 10. Updates since -02 - Removed discussion of alternative mechanisms - Changed from NOTIFY transport to PUBLISH transport. - Changed package name from "rtcp-xr" to "perfrpt" - Corrected call flows. - Minor updates to message body format. - Added IANA registration for perfrpt SIP Event Package and application/rtcp-xr MIME registration. - Added more discussion for motivation and reasons why SNMP is not suitable 11. Contributors The authors would like to thank Dave Oran and Tom Redman for their discussions. 12 Informative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] 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. [3] Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003. [4] Friedman, T., Caceres, R. and A. Clark, "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, November 2003. [5] Huitema, C., "Real Time Control Protocol (RTCP) attribute in Session Description Protocol (SDP)", RFC 3605, October 2003. [6] Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002. [7] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. Johnston, et al. Expires January 16, 2005 [Page 16] Internet-Draft RTCP Summary Delivery July 2004 [8] Niemi, A., "An Event State Publication Extension to the Session Initiation Protocol (SIP)", draft-ietf-sip-publish-04 (work in progress), May 2004. Authors' Addresses Alan Johnston MCI 100 South 4th Street St. Louis, MO 63104 EMail: alan.johnston@mci.com Henry Sinnreich MCI 400 International Parkway Richardson, TX 75081 EMail: henry.sinnreich@mci.com Alan Clark Telchemy Incorporated 3360 Martins Farm Road, Suite 200 Suwanee, GA 30024 EMail: alan@telchemy.com Amy Pendleton Nortel Networks 2380 Performance Drive Richardson, TX 75081 EMail: aspen@nortelnetworks.com Johnston, et al. Expires January 16, 2005 [Page 17] Internet-Draft RTCP Summary Delivery July 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in 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 made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Johnston, et al. Expires January 16, 2005 [Page 18]