< draft-ietf-dccp-spec-10.txt   draft-ietf-dccp-spec-11.txt >
Internet Engineering Task Force Eddie Kohler Internet Engineering Task Force Eddie Kohler
INTERNET-DRAFT UCLA INTERNET-DRAFT UCLA
draft-ietf-dccp-spec-10.txt Mark Handley draft-ietf-dccp-spec-11.txt Mark Handley
Expires: 7 September 2005 UCL Expires: 10 September 2005 UCL
Sally Floyd Sally Floyd
ICIR ICIR
7 March 2005 10 March 2005
Datagram Congestion Control Protocol (DCCP) Datagram Congestion Control Protocol (DCCP)
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of section 3 of RFC 3667. By submitting this Internet-Draft, each of section 3 of RFC 3667. By submitting this Internet-Draft, each
author represents that any applicable patent or other IPR claims of 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 is aware have been or will be disclosed, and any of
which he or she become aware will be disclosed, in accordance with which he or she become aware will be disclosed, in accordance with
skipping to change at page 1, line 37 skipping to change at page 1, line 37
months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress." reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on 7 September 2005. This Internet-Draft will expire on 10 September 2005.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2005). All Rights Reserved.
Abstract Abstract
The Datagram Congestion Control Protocol (DCCP) is a transport The Datagram Congestion Control Protocol (DCCP) is a transport
protocol that provides bidirectional unicast connections of protocol that provides bidirectional unicast connections of
congestion-controlled unreliable datagrams. DCCP is suitable for congestion-controlled unreliable datagrams. DCCP is suitable for
applications that transfer fairly large amounts of data, but can applications that transfer fairly large amounts of data, but can
benefit from control over the tradeoff between timeliness and benefit from control over the tradeoff between timeliness and
reliability. reliability.
skipping to change at page 5, line 16 skipping to change at page 5, line 16
1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 10
2. Design Rationale. . . . . . . . . . . . . . . . . . . . . . . 11 2. Design Rationale. . . . . . . . . . . . . . . . . . . . . . . 11
3. Conventions and Terminology . . . . . . . . . . . . . . . . . 12 3. Conventions and Terminology . . . . . . . . . . . . . . . . . 12
3.1. Numbers and Fields . . . . . . . . . . . . . . . . . . . 12 3.1. Numbers and Fields . . . . . . . . . . . . . . . . . . . 12
3.2. Parts of a Connection. . . . . . . . . . . . . . . . . . 13 3.2. Parts of a Connection. . . . . . . . . . . . . . . . . . 13
3.3. Features . . . . . . . . . . . . . . . . . . . . . . . . 13 3.3. Features . . . . . . . . . . . . . . . . . . . . . . . . 13
3.4. Round-Trip Times . . . . . . . . . . . . . . . . . . . . 14 3.4. Round-Trip Times . . . . . . . . . . . . . . . . . . . . 14
3.5. Security Limitation. . . . . . . . . . . . . . . . . . . 14 3.5. Security Limitation. . . . . . . . . . . . . . . . . . . 14
3.6. Robustness Principle . . . . . . . . . . . . . . . . . . 14 3.6. Robustness Principle . . . . . . . . . . . . . . . . . . 14
4. Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4. Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1. Packet Types . . . . . . . . . . . . . . . . . . . . . . 15 4.1. Packet Types . . . . . . . . . . . . . . . . . . . . . . 15
4.2. Sequence Numbers . . . . . . . . . . . . . . . . . . . . 16 4.2. Sequence Numbers . . . . . . . . . . . . . . . . . . . . 16
4.3. States . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.3. States . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.4. Congestion Control . . . . . . . . . . . . . . . . . . . 18 4.4. Congestion Control . . . . . . . . . . . . . . . . . . . 19
4.5. Features . . . . . . . . . . . . . . . . . . . . . . . . 19 4.5. Features . . . . . . . . . . . . . . . . . . . . . . . . 20
4.6. Differences From TCP . . . . . . . . . . . . . . . . . . 20 4.6. Differences From TCP . . . . . . . . . . . . . . . . . . 21
4.7. Example Connection . . . . . . . . . . . . . . . . . . . 21 4.7. Example Connection . . . . . . . . . . . . . . . . . . . 22
5. Packet Formats. . . . . . . . . . . . . . . . . . . . . . . . 23 5. Packet Formats. . . . . . . . . . . . . . . . . . . . . . . . 23
5.1. Generic Header . . . . . . . . . . . . . . . . . . . . . 23 5.1. Generic Header . . . . . . . . . . . . . . . . . . . . . 24
5.2. DCCP-Request Packets . . . . . . . . . . . . . . . . . . 27 5.2. DCCP-Request Packets . . . . . . . . . . . . . . . . . . 27
5.3. DCCP-Response Packets. . . . . . . . . . . . . . . . . . 28 5.3. DCCP-Response Packets. . . . . . . . . . . . . . . . . . 28
5.4. DCCP-Data, DCCP-Ack, and DCCP-DataAck Packets. . . . . . 28 5.4. DCCP-Data, DCCP-Ack, and DCCP-DataAck Packets. . . . . . 29
5.5. DCCP-CloseReq and DCCP-Close Packets . . . . . . . . . . 30 5.5. DCCP-CloseReq and DCCP-Close Packets . . . . . . . . . . 30
5.6. DCCP-Reset Packets . . . . . . . . . . . . . . . . . . . 30 5.6. DCCP-Reset Packets . . . . . . . . . . . . . . . . . . . 31
5.7. DCCP-Sync and DCCP-SyncAck Packets . . . . . . . . . . . 33 5.7. DCCP-Sync and DCCP-SyncAck Packets . . . . . . . . . . . 34
5.8. Options. . . . . . . . . . . . . . . . . . . . . . . . . 34 5.8. Options. . . . . . . . . . . . . . . . . . . . . . . . . 35
5.8.1. Padding Option. . . . . . . . . . . . . . . . . . . 36 5.8.1. Padding Option. . . . . . . . . . . . . . . . . . . 36
5.8.2. Mandatory Option. . . . . . . . . . . . . . . . . . 36 5.8.2. Mandatory Option. . . . . . . . . . . . . . . . . . 37
6. Feature Negotiation . . . . . . . . . . . . . . . . . . . . . 37 6. Feature Negotiation . . . . . . . . . . . . . . . . . . . . . 38
6.1. Change Options . . . . . . . . . . . . . . . . . . . . . 37 6.1. Change Options . . . . . . . . . . . . . . . . . . . . . 38
6.2. Confirm Options. . . . . . . . . . . . . . . . . . . . . 38 6.2. Confirm Options. . . . . . . . . . . . . . . . . . . . . 39
6.3. Reconciliation Rules . . . . . . . . . . . . . . . . . . 38 6.3. Reconciliation Rules . . . . . . . . . . . . . . . . . . 39
6.3.1. Server-Priority . . . . . . . . . . . . . . . . . . 39 6.3.1. Server-Priority . . . . . . . . . . . . . . . . . . 39
6.3.2. Non-Negotiable. . . . . . . . . . . . . . . . . . . 39 6.3.2. Non-Negotiable. . . . . . . . . . . . . . . . . . . 40
6.4. Feature Numbers. . . . . . . . . . . . . . . . . . . . . 39 6.4. Feature Numbers. . . . . . . . . . . . . . . . . . . . . 40
6.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 40 6.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 41
6.6. Option Exchange. . . . . . . . . . . . . . . . . . . . . 42 6.6. Option Exchange. . . . . . . . . . . . . . . . . . . . . 42
6.6.1. Normal Exchange . . . . . . . . . . . . . . . . . . 42 6.6.1. Normal Exchange . . . . . . . . . . . . . . . . . . 43
6.6.2. Processing Received Options . . . . . . . . . . . . 43 6.6.2. Processing Received Options . . . . . . . . . . . . 43
6.6.3. Loss and Retransmission . . . . . . . . . . . . . . 45 6.6.3. Loss and Retransmission . . . . . . . . . . . . . . 45
6.6.4. Reordering. . . . . . . . . . . . . . . . . . . . . 46 6.6.4. Reordering. . . . . . . . . . . . . . . . . . . . . 46
6.6.5. Preference Changes. . . . . . . . . . . . . . . . . 47 6.6.5. Preference Changes. . . . . . . . . . . . . . . . . 47
6.6.6. Simultaneous Negotiation. . . . . . . . . . . . . . 47 6.6.6. Simultaneous Negotiation. . . . . . . . . . . . . . 47
6.6.7. Unknown Features. . . . . . . . . . . . . . . . . . 47 6.6.7. Unknown Features. . . . . . . . . . . . . . . . . . 47
6.6.8. Invalid Options . . . . . . . . . . . . . . . . . . 48 6.6.8. Invalid Options . . . . . . . . . . . . . . . . . . 48
6.6.9. Mandatory Feature Negotiation . . . . . . . . . . . 48 6.6.9. Mandatory Feature Negotiation . . . . . . . . . . . 49
7. Sequence Numbers. . . . . . . . . . . . . . . . . . . . . . . 49 7. Sequence Numbers. . . . . . . . . . . . . . . . . . . . . . . 49
7.1. Variables. . . . . . . . . . . . . . . . . . . . . . . . 49 7.1. Variables. . . . . . . . . . . . . . . . . . . . . . . . 50
7.2. Initial Sequence Numbers . . . . . . . . . . . . . . . . 50 7.2. Initial Sequence Numbers . . . . . . . . . . . . . . . . 50
7.3. Quiet Time . . . . . . . . . . . . . . . . . . . . . . . 51 7.3. Quiet Time . . . . . . . . . . . . . . . . . . . . . . . 51
7.4. Acknowledgement Numbers. . . . . . . . . . . . . . . . . 51 7.4. Acknowledgement Numbers. . . . . . . . . . . . . . . . . 52
7.5. Validity and Synchronization . . . . . . . . . . . . . . 52 7.5. Validity and Synchronization . . . . . . . . . . . . . . 52
7.5.1. Sequence and Acknowledgement Number 7.5.1. Sequence and Acknowledgement Number
Windows. . . . . . . . . . . . . . . . . . . . . . . . . . 52 Windows. . . . . . . . . . . . . . . . . . . . . . . . . . 53
7.5.2. Sequence Window Feature . . . . . . . . . . . . . . 53 7.5.2. Sequence Window Feature . . . . . . . . . . . . . . 54
7.5.3. Sequence-Validity Rules . . . . . . . . . . . . . . 54 7.5.3. Sequence-Validity Rules . . . . . . . . . . . . . . 54
7.5.4. Handling Sequence-Invalid Packets . . . . . . . . . 56 7.5.4. Handling Sequence-Invalid Packets . . . . . . . . . 56
7.5.5. Sequence Number Attacks . . . . . . . . . . . . . . 57 7.5.5. Sequence Number Attacks . . . . . . . . . . . . . . 57
7.5.6. Examples. . . . . . . . . . . . . . . . . . . . . . 58 7.5.6. Examples. . . . . . . . . . . . . . . . . . . . . . 58
7.6. Short Sequence Numbers . . . . . . . . . . . . . . . . . 59 7.6. Short Sequence Numbers . . . . . . . . . . . . . . . . . 59
7.6.1. Allow Short Sequence Numbers Feature. . . . . . . . 60 7.6.1. Allow Short Sequence Numbers Feature. . . . . . . . 60
7.6.2. When to Avoid Short Sequence Numbers. . . . . . . . 60 7.6.2. When to Avoid Short Sequence Numbers. . . . . . . . 60
7.7. NDP Count and Detecting Application Loss . . . . . . . . 61 7.7. NDP Count and Detecting Application Loss . . . . . . . . 61
7.7.1. Usage Notes . . . . . . . . . . . . . . . . . . . . 62 7.7.1. Usage Notes . . . . . . . . . . . . . . . . . . . . 62
7.7.2. Send NDP Count Feature. . . . . . . . . . . . . . . 62 7.7.2. Send NDP Count Feature. . . . . . . . . . . . . . . 62
skipping to change at page 9, line 6 skipping to change at page 9, line 6
A.3. Clearing State . . . . . . . . . . . . . . . . . . . . . 121 A.3. Clearing State . . . . . . . . . . . . . . . . . . . . . 121
A.4. Processing Acknowledgements. . . . . . . . . . . . . . . 122 A.4. Processing Acknowledgements. . . . . . . . . . . . . . . 122
B. Appendix: Partial Checksumming Design Motivation. . . . . . . 123 B. Appendix: Partial Checksumming Design Motivation. . . . . . . 123
Normative References . . . . . . . . . . . . . . . . . . . . . . 124 Normative References . . . . . . . . . . . . . . . . . . . . . . 124
Informative References . . . . . . . . . . . . . . . . . . . . . 125 Informative References . . . . . . . . . . . . . . . . . . . . . 125
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 127 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 127
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 127 Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 127
Intellectual Property. . . . . . . . . . . . . . . . . . . . . . 128 Intellectual Property. . . . . . . . . . . . . . . . . . . . . . 128
List of Tables List of Tables
Table 1: DCCP Packet Types . . . . . . . . . . . . . . . . . . . 25 Table 1: DCCP Packet Types . . . . . . . . . . . . . . . . . . . 26
Table 2: DCCP Reset Codes. . . . . . . . . . . . . . . . . . . . 33 Table 2: DCCP Reset Codes. . . . . . . . . . . . . . . . . . . . 33
Table 3: DCCP Options. . . . . . . . . . . . . . . . . . . . . . 35 Table 3: DCCP Options. . . . . . . . . . . . . . . . . . . . . . 35
Table 4: DCCP Feature Numbers. . . . . . . . . . . . . . . . . . 39 Table 4: DCCP Feature Numbers. . . . . . . . . . . . . . . . . . 40
Table 5: DCCP Congestion Control Identifiers . . . . . . . . . . 80 Table 5: DCCP Congestion Control Identifiers . . . . . . . . . . 80
Table 6: DCCP Ack Vector States. . . . . . . . . . . . . . . . . 90 Table 6: DCCP Ack Vector States. . . . . . . . . . . . . . . . . 90
Table 7: DCCP Drop Codes . . . . . . . . . . . . . . . . . . . . 96 Table 7: DCCP Drop Codes . . . . . . . . . . . . . . . . . . . . 96
1. Introduction 1. Introduction
The Datagram Congestion Control Protocol (DCCP) is a transport The Datagram Congestion Control Protocol (DCCP) is a transport
protocol that implements bidirectional, unicast connections of protocol that implements bidirectional, unicast connections of
congestion-controlled, unreliable datagrams. Specifically, DCCP congestion-controlled, unreliable datagrams. Specifically, DCCP
provides: provides:
skipping to change at page 12, line 40 skipping to change at page 12, line 40
We occasionally refer to the "left" and "right" sides of a bit We occasionally refer to the "left" and "right" sides of a bit
field. "Left" means towards the most significant bit, and "right" field. "Left" means towards the most significant bit, and "right"
means towards the least significant bit. means towards the least significant bit.
Random numbers in DCCP are used for their security properties, and Random numbers in DCCP are used for their security properties, and
SHOULD be chosen according to the guidelines in RFC 1750. SHOULD be chosen according to the guidelines in RFC 1750.
All operations on DCCP sequence numbers, and comparisons such as All operations on DCCP sequence numbers, and comparisons such as
"greater" and "greatest", use circular arithmetic modulo 2**48. "greater" and "greatest", use circular arithmetic modulo 2**48.
This form of arithmetic preserves the relationships between sequence This form of arithmetic preserves the relationships between sequence
numbers as they roll over from 2**48 - 1 to 0. Note that the common numbers as they roll over from 2**48 - 1 to 0. Implementation
strategies for DCCP sequence numbers will resemble those for other
circular arithmetic spaces, including TCP's sequence numbers [RFC
793] and DNS's serial numbers [RFC 1982]. Note that the common
technique for implementing circular comparison using two's- technique for implementing circular comparison using two's-
complement arithmetic, whereby A < B using circular arithmetic if complement arithmetic, whereby A < B using circular arithmetic if
and only if (A - B) < 0 using conventional two's-complement and only if (A - B) < 0 using conventional two's-complement
arithmetic, may be used for DCCP sequence numbers, provided they are arithmetic, may be used for DCCP sequence numbers, provided they are
stored in the most significant 48 bits of 64-bit integers. stored in the most significant 48 bits of 64-bit integers.
Reserved bitfields in DCCP packet headers MUST be set to zero by Reserved bitfields in DCCP packet headers MUST be set to zero by
senders, and MUST be ignored by receivers, unless otherwise senders, and MUST be ignored by receivers, unless otherwise
specified. This is to allow for future protocol extensions. In specified. This is to allow for future protocol extensions. In
particular, DCCP processors MUST NOT reset a DCCP connection simply particular, DCCP processors MUST NOT reset a DCCP connection simply
skipping to change at page 125, line 41 skipping to change at page 125, line 41
[BB01] S.M. Bellovin and M. Blaze. Cryptographic Modes of Operation [BB01] S.M. Bellovin and M. Blaze. Cryptographic Modes of Operation
for the Internet. 2nd NIST Workshop on Modes of Operation, for the Internet. 2nd NIST Workshop on Modes of Operation,
August 2001. August 2001.
[BEL98] S.M. Bellovin. Cryptography and the Internet. Proc. CRYPTO [BEL98] S.M. Bellovin. Cryptography and the Internet. Proc. CRYPTO
'98 (LNCS 1462), pp46-55, August, 1988. '98 (LNCS 1462), pp46-55, August, 1988.
[CCID 2 PROFILE] S. Floyd and E. Kohler. Profile for DCCP [CCID 2 PROFILE] S. Floyd and E. Kohler. Profile for DCCP
Congestion Control ID 2: TCP-like Congestion Control. draft- Congestion Control ID 2: TCP-like Congestion Control. draft-
ietf-dccp-ccid2-08.txt, work in progress, November 2004. ietf-dccp-ccid2-10.txt, work in progress, March 2005.
[CCID 3 PROFILE] S. Floyd, E. Kohler, and J. Padhye. Profile for [CCID 3 PROFILE] S. Floyd, E. Kohler, and J. Padhye. Profile for
DCCP Congestion Control ID 3: TFRC Congestion Control. draft- DCCP Congestion Control ID 3: TFRC Congestion Control. draft-
ietf-dccp-ccid3-08.txt, work in progress, November 2004. ietf-dccp-ccid3-11.txt, work in progress, March 2005.
[M85] Robert T. Morris. A Weakness in the 4.2BSD Unix TCP/IP [M85] Robert T. Morris. A Weakness in the 4.2BSD Unix TCP/IP
Software. Computer Science Technical Report 117, AT&T Bell Software. Computer Science Technical Report 117, AT&T Bell
Laboratories, Murray Hill, NJ, February 1985. Laboratories, Murray Hill, NJ, February 1985.
[PMTUD] Matt Mathis, John Heffner, and Kevin Lahey. Path MTU [PMTUD] Matt Mathis, John Heffner, and Kevin Lahey. Path MTU
Discovery. draft-ietf-pmtud-method-01.txt, work in progress, Discovery. draft-ietf-pmtud-method-01.txt, work in progress,
February 2004. February 2004.
[RFC 792] J. Postel, editor. Internet Control Message Protocol. [RFC 792] J. Postel, editor. Internet Control Message Protocol.
skipping to change at page 126, line 18 skipping to change at page 126, line 18
[RFC 1750] D. Eastlake, S. Crocker, and J. Schiller. Randomness [RFC 1750] D. Eastlake, S. Crocker, and J. Schiller. Randomness
Recommendations for Security. RFC 1750. Recommendations for Security. RFC 1750.
[RFC 1812] F. Baker, editor. Requirements for IP Version 4 Routers. [RFC 1812] F. Baker, editor. Requirements for IP Version 4 Routers.
RFC 1812. RFC 1812.
[RFC 1948] S. Bellovin. Defending Against Sequence Number Attacks. [RFC 1948] S. Bellovin. Defending Against Sequence Number Attacks.
RFC 1948. RFC 1948.
[RFC 1982] R. Elz and R. Bush. Serial Number Arithmetic. RFC 1982.
[RFC 2018] M. Mathis, J. Mahdavi, S. Floyd, and A. Romanow. TCP [RFC 2018] M. Mathis, J. Mahdavi, S. Floyd, and A. Romanow. TCP
Selective Acknowledgement Options. RFC 2018. Selective Acknowledgement Options. RFC 2018.
[RFC 2401] S. Kent and R. Atkinson. Security Architecture for the [RFC 2401] S. Kent and R. Atkinson. Security Architecture for the
Internet Protocol. RFC 2401. Internet Protocol. RFC 2401.
[RFC 2463] A. Conta and S. Deering. Internet Control Message [RFC 2463] A. Conta and S. Deering. Internet Control Message
Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6)
Specification. RFC 2463. Specification. RFC 2463.
skipping to change at page 127, line 46 skipping to change at page 127, line 46
UK UK
Sally Floyd <floyd@icir.org> Sally Floyd <floyd@icir.org>
ICSI Center for Internet Research ICSI Center for Internet Research
1947 Center Street, Suite 600 1947 Center Street, Suite 600
Berkeley, CA 94704 Berkeley, CA 94704
USA USA
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society 2004. This document is subject Copyright (C) The Internet Society 2005. This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
 End of changes. 23 change blocks. 
35 lines changed or deleted 40 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/