draft-ietf-rohc-tcp-requirements-06.txt
Network Working Group Lars-Erik Jonsson Network Working Group L-E. Jonsson
INTERNET-DRAFT Ericsson INTERNET-DRAFT Ericsson
Expires: December 2003 June 12, 2003 Expires: December 2004 June 9, 2004
Requirements on ROHC TCP/IP Header Compression Requirements on ROHC TCP/IP Header Compression
<draft-ietf-rohc-tcp-requirements-06.txt> <draft-ietf-rohc-tcp-requirements-07.txt>
This document is an Internet-Draft and is in full conformance with By submitting this Internet-Draft, I (we) certify that any applicable
all provisions of Section 10 of RFC2026. patent or other IPR claims of which I am (we are) aware have been
disclosed, and any of which I (we) become aware will be disclosed, in
accordance with RFC 3668 (BCP 79).
By submitting this Internet-Draft, I (we) accept the provisions of
Section 3 of RFC 3667 (BCP 78).
Task Force (IETF), its areas, and its working groups. Note that other Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts. groups may also distribute working documents as Internet-Drafts.
material or cite them other than as "work in progress". material or cite them other than as "work in progress".
skipping to change at page 1, line 40
This document is a submission of the IETF ROHC WG. Comments should be This document is a submission of the IETF ROHC WG. Comments should be
directed to the ROHC WG mailing list, rohc@ietf.org. directed to the ROHC WG mailing list, rohc@ietf.org.
This document contains requirements on the TCP/IP header compression This document contains requirements on the TCP/IP header compression
scheme (profile) to be developed by the ROHC WG. The document scheme (profile) to be developed by the ROHC WG. The document
discusses the scope of TCP compression, performance considerations, discusses the scope of TCP compression, performance considerations,
assumptions on the surrounding environment, as well as IPR concerns. assumptions on the surrounding environment, as well as IPR concerns.
The structure of this document is inherited from the document The structure of this document is inherited from the document
defining RTP/UDP/IP requirements for ROHC. defining RTP/UDP/IP requirements [5] for ROHC.
1. Introduction.....................................................2
2. Header Compression Requirements..................................2
2.1. Impact on Internet Infrastructure...........................3
2.2. Supported Headers and Kinds of TCP Streams..................3
2.3. Performance Issues..........................................4
2.4. Requirements Related to Link Layer Characteristics..........6
2.5. Intellectual Property Rights (IPR)..........................7
3. Security Consideration...........................................7
4. IANA Considerations..............................................7
5. Acknowledgments..................................................7
6. Authors' Address.................................................7
7. References.......................................................8
1. Introduction 1. Introduction
The goal of the ROHC WG is to develop header compression schemes that The goal of the ROHC WG is to develop header compression schemes that
perform well over links with high error rates and long link roundtrip perform well over links with high error rates and long link roundtrip
times. The schemes must perform well for cellular links, using times. The schemes must perform well for cellular links, using
technologies such as WCDMA, EDGE, and CDMA-2000. However, the schemes technologies such as WCDMA, EDGE, and CDMA-2000. However, the schemes
should also be applicable to other future link technologies with high should also be applicable to other future link technologies with high
loss and long roundtrip times. loss and long roundtrip times.
The main objective for ROHC has been robust compression of The main objective for ROHC has been robust compression of
IP/UDP/RTP, but the WG is also chartered to develop new header IP/UDP/RTP, but the WG is also chartered to develop new header
compression solutions for IP/TCP [RFC-791, RFC-793]. Since TCP compression solutions for IP/TCP [1], [2]. Since TCP traffic, in
traffic, in contrast to RTP, has usually been sent over reliable contrast to RTP, has usually been sent over reliable links, existing
links, existing schemes for TCP [RFC-1144, RFC-2507] have not schemes for TCP, [3] and [4], have not experienced the same
experienced the same robustness problems as RTP compression. However, robustness problems as RTP compression. However, there are still many
there are still many scenarios where TCP header compression will be scenarios where TCP header compression will be implemented over less
implemented over less reliable links [RFC-3150, PILC-ARQ], making reliable links [11], [12], making robustness an important objective
robustness an important objective also for the new TCP compression also for the new TCP compression scheme. Other, equally important,
scheme. Other, equally important, objectives for ROHC TCP compression objectives for ROHC TCP compression are: improved compression
are: improved compression efficiency, enhanced capabilities for efficiency, enhanced capabilities for compression of header fields
compression of header fields including TCP options, and finally including TCP options, and finally incorporation of TCP compression
incorporation of TCP compression into the ROHC framework [RFC-3095]. into the ROHC framework [6].
2. Header Compression Requirements 2. Header Compression Requirements
The following requirements have, more or less arbitrarily, been The following requirements have, more or less arbitrarily, been
divided into five groups. The first group deals with requirements divided into five groups. The first group deals with requirements
concerning the impact of a header compression scheme on the rest of concerning the impact of a header compression scheme on the rest of
the Internet infrastructure. The second group defines what kind of the Internet infrastructure. The second group defines what kind of
headers must be compressed efficiently, while the third and fourth headers must be compressed efficiently, while the third and fourth
groups concern performance requirements and capability requirements groups concern performance requirements and capability requirements
which stem from the properties of the anticipated link technologies. which stem from the properties of the anticipated link technologies.
Finally, the fifth section discusses Intellectual Property Rights Finally, the fifth section discusses Intellectual Property Rights
related to ROHC TCP compression. related to ROHC TCP compression.
2.1. Impact on Internet Infrastructure 2.1. Impact on Internet Infrastructure
1. Transparency: When a header is compressed and then decompressed, 1. Transparency: When a header is compressed and then decompressed,
the resulting header must be semantically identical to the the resulting header must be semantically identical to the
original header. If this cannot be achieved, the packet original header. If this cannot be achieved, the packet containing
containing the erroneous header must be discarded. the erroneous header must be discarded.
Justification: The header compression process must not produce Justification: The header compression process must not produce
headers that might cause problems for any current or future part headers that might cause problems for any current or future part
of the Internet infrastructure. of the Internet infrastructure.
Note: The ROHC WG has not found a case where "semantically Note: The ROHC WG has not found a case where "semantically
identical" is not the same as "bitwise identical". identical" is not the same as "bitwise identical".
2. Ubiquity: Must not require modifications to existing IP (v4 or 2. Ubiquity: Must not require modifications to existing IP (v4 or
v6) or TCP implementations. v6) or TCP implementations.
Justification: Ease of deployment. Justification: Ease of deployment.
Note: The ROHC WG may recommend changes that would increase the Note: The ROHC WG may recommend changes that would increase the
compression efficiency for the TCP streams emitted by compression efficiency for the TCP streams emitted by
implementations. However, ROHC cannot rely on such implementations. However, ROHC cannot rely on such recommendations
recommendations being followed. being followed.
Note: Several TCP variants are currently in use on the Internet. Note: Several TCP variants are currently in use on the Internet.
This requirement implies that the header compression scheme must This requirement implies that the header compression scheme must
work efficiently and correctly for all expected TCP variants. work efficiently and correctly for all expected TCP variants.
2.2. Supported Headers and Kinds of TCP Streams 2.2. Supported Headers and Kinds of TCP Streams
1. IPv4 and IPv6: Must support both IPv4 and IPv6. This means that 1. IPv4 and IPv6: Must support both IPv4 and IPv6. This means that
all possible changes in the IP header fields must be handled by all possible changes in the IP header fields must be handled by
the compression scheme, and commonly changing fields should be the compression scheme, and commonly changing fields should be
compressed efficiently. Compression must not be disabled if IPv4 compressed efficiently. Compression must not be disabled if IPv4
Options or IPv6 Extensions are present. The compression scheme Options or IPv6 Extensions are present. The compression scheme
must further consider as normal operation the scenario where must further consider as normal operation the scenario where
Explicit Congestion Notification (ECN) [RFC-3168] is applied and Explicit Congestion Notification (ECN) [10] is applied and support
support efficient compression also in the case when the ECN bits efficient compression also in the case when the ECN bits are used.
are used.
Justification: IPv4 and IPv6 will both be around for the Justification: IPv4 and IPv6 will both be around for the
foreseeable future, and Options/Extensions are expected to be foreseeable future, and Options/Extensions are expected to be more
more commonly used. ECN is expected to have a breakthrough and be commonly used. ECN is expected to have a breakthrough and be
widely deployed, especially in combination with TCP. widely deployed, especially in combination with TCP.
2. Mobile IP: The kinds of headers used by Mobile IP{v4,v6} must be 2. Mobile IP: The kinds of headers used by Mobile IP{v4,v6} must be
supported and should be compressed efficiently. For IPv4 these supported and should be compressed efficiently. For IPv4 these
include headers of tunneled packets. For IPv6 they include include headers of tunneled packets. For IPv6 they include headers
headers containing the Routing Header, the Binding Update containing the Routing Header, the Binding Update Destination
Destination Option, and the Home Address Option. Option, and the Home Address Option.
Justification: It is very likely that Mobile IP will be used by Justification: It is very likely that Mobile IP will be used by
cellular devices. cellular devices.
3. Generality: Must handle all headers from arbitrary TCP streams. 3. Generality: Must handle all headers from arbitrary TCP streams.
Justification: There must be a generic scheme which can compress Justification: There must be a generic scheme which can compress
reasonably well for any TCP traffic pattern. This does not reasonably well for any TCP traffic pattern. This does not
preclude optimizations for certain traffic patterns. preclude optimizations for certain traffic patterns.
4. IPSEC: The scheme should be able to compress headers containing 4. IPSEC: The scheme should be able to compress headers containing
IPSEC sub-headers. IPSEC sub-headers.
Justification: IPSEC is expected to be used to provide necessary Justification: IPSEC is expected to be used to provide necessary
end-to-end security. end-to-end security.
Note: It is not possible to compress the encrypted part of an ESP Note: It is not possible to compress the encrypted part of an ESP
header, nor the cryptographic data in an AH header. header, nor the cryptographic data in an AH header.
5. TCP: All fields supported by [RFC-2507] should be handled with 5. TCP: All fields supported by [4] should be handled with efficient
efficient compression, and so also the cases when the SYN, FIN or compression, and so also the cases when the SYN, FIN or TCP ECN
TCP ECN [RFC-3168] bits are set. [10] bits are set.
Justification: These bits are expected to be commonly used. Justification: These bits are expected to be commonly used.
6. TCP options: The scheme must support compression of packets with 6. TCP options: The scheme must support compression of packets with
any TCP option present, even if the option itself is not any TCP option present, even if the option itself is not
compressed. Further, for some commonly used options the scheme compressed. Further, for some commonly used options the scheme
should provide compression mechanisms also for the options. should provide compression mechanisms also for the options.
Justification: Since various TCP options are commonly used, Justification: Since various TCP options are commonly used,
applicability of the compression scheme would be significantly applicability of the compression scheme would be significantly
reduced if packets with options could not be compressed. reduced if packets with options could not be compressed.
Note: Options that should be compressed are: Note: Options that should be compressed are:
- Selective Acknowledgement (SACK), [RFC-2018, RFC-2883] - Selective Acknowledgement (SACK), [8], [9]
- Timestamp, [RFC-1323] - Timestamp, [7]
2.3. Performance Issues 2.3. Performance Issues
1. Performance/Spectral Efficiency: The scheme must provide low 1. Performance/Spectral Efficiency: The scheme must provide low
relative overhead under expected operating conditions; relative overhead under expected operating conditions; compression
compression efficiency should be better than for RFC2507 under efficiency should be better than for RFC 2507 [4] under equivalent
equivalent operating conditions. operating conditions.
Justification: Spectrum efficiency is a primary goal. Justification: Spectrum efficiency is a primary goal.
Note: The relative overhead is the average header overhead Note: The relative overhead is the average header overhead
relative to the payload. Any auxiliary (e.g., control or relative to the payload. Any auxiliary (e.g., control or feedback)
feedback) channels used by the scheme should be taken into channels used by the scheme should be taken into account when
account when calculating the header overhead. calculating the header overhead.
2. Losses between compressor and decompressor: The scheme should make 2. Losses between compressor and decompressor: The scheme should make
sure that losses between compressor and decompressor do not sure losses between compressor and decompressor do not result in
result in losses of subsequent packets, or cause damage to the losses of subsequent packets, or cause damage to the context that
context that result in incorrect decompression of subsequent result in incorrect decompression of subsequent packet headers.
packet headers.
Justification: Even though link layer retransmission in most cases Justification: Even though link layer retransmission in most cases
is expected to almost eliminate losses between compressor and is expected to almost eliminate losses between compressor and
decompressor, there are still many scenarios where TCP header decompressor, there are still many scenarios where TCP header
compression will be implemented over less reliable links [RFC- compression will be implemented over less reliable links [11],
3150, PILC-ARQ]. In such cases, loss propagation due to header [12]. In such cases, loss propagation due to header compression
compression could affect certain TCP mechanisms that are capable could affect certain TCP mechanisms that are capable of handling
of handling some losses, and have a negative impact on the some losses, and have a negative impact on the performance of TCP
performance of TCP loss recovery. loss recovery.
3. Residual errors in compressed headers: Residual errors in 3. Residual errors in compressed headers: Residual errors in
compressed headers may result in delivery of incorrectly compressed headers may result in delivery of incorrectly
decompressed headers not only for the damaged packet itself, but decompressed headers not only for the damaged packet itself, but
also for subsequent packets, since errors may be saved in the also for subsequent packets, since errors may be saved in the
context state. For TCP, the compression scheme is not required to context state. For TCP, the compression scheme is not required to
implement explicit mechanisms for residual error detection, but implement explicit mechanisms for residual error detection, but
the compression scheme must not affect TCP's end-to-end the compression scheme must not affect TCP's end-to-end mechanisms
mechanisms for error detection. for error detection.
Justification: For links carrying TCP traffic, the residual error Justification: For links carrying TCP traffic, the residual error
rate is expected to be insignificant. However, residual errors rate is expected to be insignificant. However, residual errors may
may still occur, especially in the end-to-end path, and therefore still occur, especially in the end-to-end path, and therefore it
it is crucial that TCP is not prevented from handling these. is crucial that TCP is not prevented from handling these.
Note: This requirement implies that the TCP checksum must be Note: This requirement implies that the TCP checksum must be
carried unmodified in all compressed headers. carried unmodified in all compressed headers.
Note: The error detection mechanism in TCP may be able to detect Note: The error detection mechanism in TCP may be able to detect
residual bit errors, but the mechanism is not designed for this residual bit errors, but the mechanism is not designed for this
purpose, and might actually provide a rather weak protection. purpose, and might actually provide a rather weak protection.
Therefore, although it is not a requirement on the compression Therefore, although it is not a requirement on the compression
scheme, the decompressor should discard packets which are known scheme, the decompressor should discard packets which are known to
to contain residual errors. contain residual errors.
4. Short-lived TCP transfers: The scheme should provide mechanisms 4. Short-lived TCP transfers: The scheme should provide mechanisms
for efficient compression of short-lived TCP transfers, for efficient compression of short-lived TCP transfers, minimizing
minimizing the size of context initiation headers. the size of context initiation headers.
Justification: Many TCP transfers are short-lived. This may lead Justification: Many TCP transfers are short-lived. This may lead
to a low gain for header compression schemes that for all new to a low gain for header compression schemes that for all new
packet streams require full headers to be sent initially and packet streams require full headers to be sent initially and allow
allow small compressed headers only after the initiation phase. small compressed headers only after the initiation phase.
Note: This requirement implies that mechanisms for "context Note: This requirement implies that mechanisms for "context
sharing" (concurrent packet streams share context information) or sharing" (concurrent packet streams share context information) or
"context re-use" (new contexts can be built on information from "context re-use" (new contexts can be built on information from
previous contexts) should be considered. previous contexts) should be considered.
5a. Moderate Packet Misordering: The scheme should efficiently handle 5a. Moderate Packet Misordering: The scheme should efficiently handle
moderate misordering (2-3 packets) in the packet stream reaching moderate misordering (2-3 packets) in the packet stream reaching
the compressor. the compressor.
the TCP stream reaching the compressor. the TCP stream reaching the compressor.
Justification: Misordering happens regularly in the Internet. Justification: Misordering happens regularly in the Internet.
However, since the Internet is engineered to run TCP reasonably However, since the Internet is engineered to run TCP reasonably
well, excessive misordering will not be common and need not be well, excessive misordering will not be common and need not be
handled with optimum efficiency. handled with optimum efficiency.
6. Processing delay: The scheme should not contribute significantly 6. Processing delay: The scheme should not contribute significantly
to the system delay budget. to the system delay budget.
2.4. Capability Requirements Related to Link Layer Characteristics 2.4. Requirements Related to Link Layer Characteristics
1. Unidirectional links: Must be possible to implement (possibly with 1. Unidirectional links: Must be possible to implement (possibly with
less efficiency) without explicit feedback messages from less efficiency) without explicit feedback messages from
decompressor to compressor. decompressor to compressor.
Justification: There are links that do not provide a feedback Justification: There are links that do not provide a feedback
channel or where feedback is not desirable for other reasons. channel or where feedback is not desirable for other reasons.
2. Misordering between compressor and decompressor: The header 2. Misordering between compressor and decompressor: The header
compression scheme must be able to handle misordered packets compression scheme must be able to handle misordered packets
and decompressor would therefore not be applicable in many and decompressor would therefore not be applicable in many
tunneling scenarios. However, in the case of tunneling, it is tunneling scenarios. However, in the case of tunneling, it is
usually possible to get misordering indications. Therefore, the usually possible to get misordering indications. Therefore, the
compression scheme does not have to support detection of compression scheme does not have to support detection of
misordering, but can assume that such information is available misordering, but can assume that such information is available
from lower layers. from lower layers.
3. Link delay: Must operate under all expected link delay conditions. 3. Link delay: Must operate under all expected link delay conditions.
4. Header compression coexistence: The scheme must fit into the ROHC 4. Header compression coexistence: The scheme must fit into the ROHC
framework together with other ROHC profiles (e.g. [RFC-3095]). framework together with other ROHC profiles (e.g. [6]).
2.5. Intellectual Property Rights (IPR) 2.5. Intellectual Property Rights (IPR)
The ROHC WG must spend effort to achieve a high degree of The ROHC WG must spend effort to achieve a high degree of confidence
confidence that there is no IPR covering a final compression that there is no IPR covering a final compression solution for TCP.
solution for TCP.
Justification: Currently there is no TCP header compression
scheme available that can efficiently compress the packet headers
of modern TCP, e.g. with SACK, ECN, etc. ROHC is expected to fill
this gap by providing a ROHC TCP scheme that is applicable in the
wide area Internet, not only over error-prone radio links. It
must thus attempt to be as future-proof as possible, and only
unencumbered solutions will be acceptable to the Internet at
large.
3. IANA Considerations
A protocol which meets these requirements will require the IANA to Justification: Currently there is no TCP header compression scheme
assign various numbers. This document by itself, however, does not available that can efficiently compress the packet headers of modern
require any IANA involvement. TCP, e.g. with SACK, ECN, etc. ROHC is expected to fill this gap by
providing a ROHC TCP scheme that is applicable in the wide area
Internet, not only over error-prone radio links. It must thus attempt
to be as future-proof as possible, and only unencumbered solutions
will be acceptable to the Internet at large.
4. Security Considerations 3. Security Consideration
A protocol specified to meet these requirements must be able to A protocol specified to meet these requirements must be able to
compress packets containing IPSEC headers according to the IPSEC compress packets containing IPSEC headers according to the IPSEC
requirement, 2.2.4. There may be other security aspects to consider requirement, 2.2.4. There may be other security aspects to consider
in such protocols. This document by itself, however, does not add in such protocols. This document by itself, however, does not add
any security risks. any security risks.
5. Acknowledgements 4. IANA Considerations
A protocol that meets these requirements will require the IANA to
assign various numbers. This document by itself, however, does not
require any IANA involvement.
5. Acknowledgments
This document has evolved through fruitful discussions with and input This document has evolved through fruitful discussions with and input
from Gorry Fairhurst, Carsten Bormann, Mikael Degermark, Mark West, from Gorry Fairhurst, Carsten Bormann, Mikael Degermark, Mark West,
Jan Kullander, Qian Zhang, Richard Price, and Aaron Falk. The Jan Kullander, Qian Zhang, Richard Price, and Aaron Falk. The
document quality was significantly improved thanks to Peter Eriksson, document quality was significantly improved thanks to Peter Eriksson,
who made a thorough linguistic review. who made a thorough linguistic review.
6. References 6. Authors' Address
[RFC-791] Jon Postel, Internet Protocol, RFC 791, September 1981. Lars-Erik Jonsson Tel: +46 920 20 21 07
Ericsson AB Fax: +46 920 20 20 99
SE-971 28 Lulea
Sweden EMail: lars-erik.jonsson@ericsson.com
[RFC-793] Jon Postel, Transport Control Protocol, RFC 793, 7. References
[RFC-1144] Van Jacobson, "Compressing TCP/IP Headers for Low-Speed [1] Jon Postel, Internet Protocol, RFC 791, September 1981.
Serial Links", RFC 1144, February 1990.
[RFC-2507] Mikael Degermark, Bjorn Nordgren, Stephen Pink, "IP [2] Jon Postel, Transport Control Protocol, RFC 793, September 1981.
Header Compression", RFC 2507, February 1999.
[RFC-3096] Mikael Degermark, "Requirements for IP/UDP/RTP header [3] Van Jacobson, "Compressing TCP/IP Headers for Low-Speed Serial
Links", RFC 1144, February 1990.
[4] Mikael Degermark, Bjorn Nordgren, Stephen Pink, "IP Header
Compression", RFC 2507, February 1999.
[5] Mikael Degermark, "Requirements for IP/UDP/RTP header
compression", RFC 3096, July 2001. compression", RFC 3096, July 2001.
[RFC-3095] Carsten Bormann, et. al., "Robust Header Compression [6] Carsten Bormann, et. al., "Robust Header Compression (ROHC)",
(ROHC)", RFC 3095, July 2001. RFC 3095, July 2001.
[RFC-1323] Van Jacobson, Bob Braden, Dave Borman, "TCP Extensions [7] Van Jacobson, Bob Braden, Dave Borman, "TCP Extensions for High
for High Performance", RFC 1323, May 1992. Performance", RFC 1323, May 1992.
[RFC-2018] Matt Mathis, Jamshid Mahdavi, Sally Floyd, Allyn [8] Matt Mathis, Jamshid Mahdavi, Sally Floyd, Allyn Romanow, "TCP
Romanow, "TCP Selective Acknowledgement Option", RFC Selective Acknowledgement Option", RFC 2018, October 1996.
2018, October 1996.
[RFC-2883] Sally Floyd, Jamshid Mahdavi, Matt Mathis, Matthew [9] Sally Floyd, Jamshid Mahdavi, Matt Mathis, Matthew Podolsky, "An
Podolsky, "An Extension to the Selective Acknowledgement Extension to the Selective Acknowledgement (SACK) Option for
(SACK) Option for TCP", RFC 2883, July 2000. TCP", RFC 2883, July 2000.
[RFC-3168] K. K. Ramakrishnan, Sally Floyd, David L. Black, "The [10] K. K. Ramakrishnan, Sally Floyd, David L. Black, "The Addition
Addition of Explicit Congestion Notification (ECN) to of Explicit Congestion Notification (ECN) to IP", RFC 3168,
IP", RFC 3168, September 2001. September 2001.
[RFC-3150] Spencer Dawkins, Gabriel Montenegro, Markku Kojo, [11] Spencer Dawkins, Gabriel Montenegro, Markku Kojo, Vincent
Vincent Magret, "End-to-end Performance Implications of Magret, "End-to-end Performance Implications of Slow Links", RFC
Slow Links", RFC 3150, July 2001. 3150, July 2001.
[PILC-ARQ] Gorry Fairhurst, Lloyd Wood, "Advice to link designers [12] Gorry Fairhurst, Lloyd Wood, "Advice to link designers on link
on link Automatic Repeat reQuest (ARQ)", RFC 3366, Automatic Repeat reQuest (ARQ)", RFC 3366, August 2002.
7. Author's Address Intellectual Property Statement
Lars-Erik Jonsson Tel: +46 920 20 21 07 The IETF takes no position regarding the validity or scope of any
Ericsson AB Fax: +46 920 20 20 99 Intellectual Property Rights or other rights that might be claimed to
Box 920 pertain to the implementation or use of the technology described in
SE-971 28 Lulea this document or the extent to which any license under such rights
Sweden EMail: lars-erik.jonsson@ericsson.com 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 IETF's procedures with respect to rights in IETF Documents can
be found in RFC 3667 (BCP 78) and RFC 3668 (BCP 79).
Full Copyright Statement 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.
Copyright (C) The Internet Society (2001). All Rights Reserved. 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.
This document and translations of it may be copied and furnished to Copyright Statement
The limited permissions granted above are perpetual and will not be Copyright (C) The Internet Society (2004). This document is subject
revoked by the Internet Society or its successors or assigns. to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
This document and the information contained herein is provided on an Disclaimer of Validity
This Internet-Draft expires December 12, 2003. This document and the information contained herein are provided on an
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