draft-ietf-tsvwg-udp-lite-01.txt   draft-ietf-tsvwg-udp-lite-02.txt 
Network Working Group L-A. Larzon Network Working Group L-A. Larzon
INTERNET-DRAFT Lulea University of Technology INTERNET-DRAFT Lulea University of Technology
Expires: June 2003 M. Degermark Expires: January 2003 M. Degermark
S. Pink S. Pink
The University of Arizona The University of Arizona
L-E. Jonsson (editor) L-E. Jonsson (Editor)
Ericsson Ericsson
G. Fairhurst (editor) G. Fairhurst (Editor)
University of Aberdeen University of Aberdeen
December 5, 2002 August, 2003
The UDP-Lite Protocol The UDP-Lite Protocol
<draft-ietf-tsvwg-udp-lite-01.txt> <draft-ietf-tsvwg-udp-lite-02.txt>
Status of this memo Status of this memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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.
skipping to change at page 2, line 7 skipping to change at page 13, line ?
Abstract Abstract
This document describes the UDP-Lite protocol, which is similar to This document describes the UDP-Lite protocol, which is similar to
UDP [RFC-768], but can also serve applications that in error-prone UDP [RFC-768], but can also serve applications that in error-prone
network environments prefer to have partially damaged payloads network environments prefer to have partially damaged payloads
delivered rather than discarded. If this feature is not used, UDP- delivered rather than discarded. If this feature is not used, UDP-
Lite is semantically identical to UDP. Lite is semantically identical to UDP.
Table of Contents Table of Contents
Larzon, et al. [Page 1]
1. Introduction...................................................2 1. Introduction...................................................2
2. Terminology....................................................3 2. Terminology....................................................3
3. Protocol Description...........................................3 3. Protocol Description...........................................3
3.1. Fields....................................................3 3.1. Fields....................................................3
3.2. Pseudo Header.............................................4 3.2. Pseudo Header.............................................4
3.3. Application Interface.....................................4 3.3. Application Interface.....................................4
3.4. IP Interface..............................................5 3.4. IP Interface..............................................5
3.5. Jumbograms................................................5 3.5. Jumbograms................................................5
4. Lower Layer Considerations.....................................5 4. Lower Layer Considerations.....................................6
5. Compatibility with UDP.........................................6 5. Compatibility with UDP.........................................6
6. Security Considerations........................................7 6. Security Considerations........................................7
7. IANA Considerations............................................7 7. IANA Considerations............................................8
8. References.....................................................8 8. References.....................................................8
8.1. Normative References......................................8 8.1. Normative References......................................8
8.2. Informative References....................................8 8.2. Informative References....................................9
9. Acknowledgements...............................................8 9. Acknowledgements...............................................10
10. Authors' Addresses............................................9 10. Authors' Addresses............................................11
1. Introduction 1. Introduction
Why another transport protocol? This document describes a new transport protocol, UDP-Lite, (also
known as UDPLite). This new protocol is based on three observations:
First, there is a class of applications that prefer to have damaged First, there is a class of applications that benefit from having
data delivered rather than discarded by the network. A number of damaged data delivered rather than discarded by the network. A number
codecs for voice and video fall into this class. These codecs are of codecs for voice and video fall into this class (e.g. the AMR
designed to cope better with errors in the payload than with loss of speech codec [RFC-3267], the Internet Low Bit Rate Codec [ILBRC], and
entire packets. error resilient H.263+ [ITU-H.263], H.264 [ITU-H.264; H.264] and
MPEG-4 [ISO-14496] video codecs). These codecs may be designed to
cope better with errors in the payload than with loss of entire
packets.
Second, there are a number of link technologies where data can be Second, all links that support IP transmission should use a strong
partially damaged. Several radio technologies exhibit this behavior link layer integrity check (e.g. CRC-32 [LINK]), and this MUST be
when operating at a point where cost and delay are sufficiently low. used by default for IP traffic. When the under-lying link supports
it, certain types of traffic (e.g. UDP-Lite) may benefit from a
different link behavior that permits partially damaged IP packets to
be forwaded when requested [LINK]. Several radio technologies (e.g.
[3GPP-QoS]) support this link behavior when operating at a point
where cost and delay are sufficiently low. If error-prone links are
aware of the error sensitive portion of a packet, it is also possible
for the physical link to provide greater protection to reduce the
probability of corruption of these error sensitive bytes (e.g., the
use of unequal Forward Error Correction).
Third, intermediate layers should not prevent error-tolerant Third, intermediate layers (i.e., IP and the transport layer
applications to run well in the presence of such links. The protocols) should not prevent error-tolerant applications from
intermediate layers are IP and the transport layer. IP is not a running well in the presence of such links. IP is not a problem in
problem in this regard since the IP header has no checksum that this regard, since the IP header has no checksum that covers the IP
covers the IP payload. The generally available transport protocol payload. The generally available transport protocol best suited for
best suited for these applications is UDP, since it has no overhead
for retransmission of erroneous packets, in-order delivery, or error Larzon, et al. [Page 2]
these applications is UDP, since it has no overhead for
retransmission of erroneous packets, in-order delivery, or error
correction. In IPv4 [RFC-791], the UDP checksum covers either the correction. In IPv4 [RFC-791], the UDP checksum covers either the
entire packet or nothing at all. In IPv6 [RFC-2460], the UDP checksum entire packet or nothing at all. In IPv6 [RFC-2460], the UDP checksum
is mandatory and must not be disabled. The IPv6 header does not have is mandatory and must not be disabled. The IPv6 header does not have
a header checksum and it was deemed necessary to always protect the a header checksum and it was deemed necessary to always protect the
IP addressing information by making the UDP checksum mandatory. IP addressing information by making the UDP checksum mandatory.
A transport protocol is needed that conforms to the properties of A transport protocol is needed that conforms to the properties of
link layers and applications described above [UDP-LITE]. The error- link layers and applications described above [LDP99]. The error-
detection mechanism of the transport layer must be able to protect detection mechanism of the transport layer must be able to protect
vital information such as headers, but also to optionally ignore vital information such as headers, but also to optionally ignore
errors best dealt with by the application. What should be verified by errors best dealt with by the application. The set of octets to be
the checksum is best specified by the sending application. verified by the checksum is best specified by the sending
application.
UDP-Lite provides a checksum with an optional partial coverage. When UDP-Lite provides a checksum with an optional partial coverage. When
using this option, a packet is divided into a sensitive part (covered using this option, a packet is divided into a sensitive part (covered
by the checksum) and an insensitive part (not covered by the by the checksum) and an insensitive part (not covered by the
checksum). Errors in the insensitive part will not cause the packet checksum). Errors in the insensitive part will not cause the packet
to be discarded by the transport layer at the receiving end host. to be discarded by the transport layer at the receiving end host.
When the checksum covers the entire packet, which should be the When the checksum covers the entire packet, which should be the
default, UDP-Lite is semantically identical to UDP. default, UDP-Lite is semantically identical to UDP.
Compared to UDP, the UDP-Lite partial checksum provides extra Compared to UDP, the UDP-Lite partial checksum provides extra
skipping to change at page 3, line 33 skipping to change at page 13, line ?
document are to be interpreted as described in [RFC-2119]. document are to be interpreted as described in [RFC-2119].
3. Protocol Description 3. Protocol Description
The UDP-Lite header is shown in figure 1. Its format differs from The UDP-Lite header is shown in figure 1. Its format differs from
UDP in that the Length field has been replaced with a Checksum UDP in that the Length field has been replaced with a Checksum
Coverage field. This can be done since information about UDP packet Coverage field. This can be done since information about UDP packet
length can be provided by the IP module in the same manner as for TCP length can be provided by the IP module in the same manner as for TCP
[RFC-793]. [RFC-793].
Larzon, et al. [Page 3]
0 15 16 31 0 15 16 31
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| Source | Destination | | Source | Destination |
| Port | Port | | Port | Port |
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| Checksum | | | Checksum | |
| Coverage | Checksum | | Coverage | Checksum |
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| | | |
: Payload : : Payload :
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Checksum Coverage is the number of octets, counting from the first Checksum Coverage is the number of octets, counting from the first
octet of the UDP-Lite header, that are covered by the checksum. The octet of the UDP-Lite header, that are covered by the checksum. The
UDP-Lite header MUST always be covered by the checksum. Despite this UDP-Lite header MUST always be covered by the checksum. Despite this
requirement, the Checksum Coverage is expressed in octets from the requirement, the Checksum Coverage is expressed in octets from the
beginning of the UDP-Lite header, in the same way as for UDP. A beginning of the UDP-Lite header, in the same way as for UDP. A
Checksum Coverage of zero indicates that the entire UDP-Lite packet Checksum Coverage of zero indicates that the entire UDP-Lite packet
is covered by the checksum. This means that the value of the Checksum is covered by the checksum. This means that the value of the Checksum
Coverage field MUST be either 0 or at least 8. A UDP-Lite packet with Coverage field MUST be either 0 or at least 8. A UDP-Lite packet with
a Checksum Coverage value of 1 to 7 MUST be discarded by the a Checksum Coverage value of 1 to 7 MUST be discarded by the
receiver. UDP-Lite packets with a Checksum Coverage greater than the receiver. Irrespective of the Checksum Coverage, the computed
IP length MUST also be discarded. Checksum field MUST include a pseudo-header, based on the IP header
(see below). UDP-Lite packets with a Checksum Coverage greater than
the IP length MUST also be discarded.
Checksum is the 16-bit one's complement of the one's complement sum The Checksum field is the 16-bit one's complement of the one's
of a pseudo-header of information from the IP header, the number of complement sum of a pseudo-header of information collected from the
octets specified by the Checksum Coverage (starting at the first IP header, the number of octets specified by the Checksum Coverage
octet in the UDP-Lite header), virtually padded with a zero octet at (starting at the first octet in the UDP-Lite header), virtually
the end (if necessary) to make a multiple of two octets [RFC-1071]. padded with a zero octet at the end (if necessary) to make a multiple
If the computed checksum is 0, it is transmitted as all ones (the of two octets [RFC-1071]. Prior to computation, the checksum field
equivalent in one's complement arithmetic). MUST be set to zero. If the computed checksum is 0, it is transmitted
as all ones (the equivalent in one's complement arithmetic).
The transmitted checksum MUST NOT be all zeroes. If an application Since the transmitted checksum MUST NOT be all zeroes, an application
using UDP-Lite wishes to have no protection of the packet payload, it using UDP-Lite that wishes to have no protection of the packet
should use a Checksum Coverage value of 8. This differs from the use payload, should use a Checksum Coverage value of 8. This differs from
of UDP over IPv4, in that the minimal UDP-Lite checksum always covers the use of UDP over IPv4, in that the minimal UDP-Lite checksum
the UDP-Lite protocol header, which includes the Checksum Coverage always covers the UDP-Lite protocol header, which includes the
field. Checksum Coverage field.
Larzon, et al. [Page 4]
3.2. Pseudo Header 3.2. Pseudo Header
UDP and UDP-Lite use the same conceptually prefixed pseudo header UDP and UDP-Lite use the same conceptually prefixed pseudo header
from the IP layer for the checksum. This pseudo header is different from the IP layer for the checksum. This pseudo header is different
for IPv4 and IPv6. The pseudo header of UDP-Lite is different from for IPv4 and IPv6. The pseudo header of UDP-Lite is different from
the pseudo header of UDP in one way: The value of the Length field of the pseudo header of UDP in one way: The value of the Length field of
the pseudo header is not taken from the UDP-Lite header, but rather the pseudo header is not taken from the UDP-Lite header, but rather
from information provided by the IP module. This computation is done from information provided by the IP module. This computation is done
in the same manner as for TCP [RFC-793], and implies that the Length in the same manner as for TCP [RFC-793], and implies that the Length
field of the pseudo header includes the UDP-Lite header and all field of the pseudo header includes the UDP-Lite header and all
subsequent octets in the IP payload. subsequent octets in the IP payload.
3.3. Application Interface 3.3. Application Interface
An application interface should allow the same operations as for An application interface should allow the same operations as for
UDP. In addition to this, it should provide a way for the sending UDP. In addition to this, it should provide a way for the sending
application to pass the checksum coverage value to the UDP-Lite application to pass the Checksum Coverage value to the UDP-Lite
module. There should also be a way to pass the checksum coverage module. There should also be a way to pass the Checksum Coverage
value to the receiving application, or at least let the receiving value to the receiving application, or at least let the receiving
application block delivery of packets with coverage values less than application block delivery of packets with coverage values less than
a value provided by the application. a value provided by the application.
It is RECOMMENDED that the default behavior of UDP-Lite be to mimic It is RECOMMENDED that the default behavior of UDP-Lite be to mimic
UDP by having the Checksum Coverage field match the length of the UDP by having the Checksum Coverage field match the length of the
UDP-Lite packet, and verify the entire packet. Applications that want UDP-Lite packet, and verify the entire packet. Applications that wish
to define the payload as partially insensitive to bit errors (e.g. to define the payload as partially insensitive to bit errors (e.g.
error tolerant codecs using RTP [RFC-1889]) should do that by an error tolerant codecs using RTP [RFC-1889]) should do this by an
explicit system call on the sender side. Applications that wish to explicit system call on the sender side. Applications that wish to
receive payloads that were only partially covered by a checksum receive payloads that were only partially covered by a checksum
should inform the receiving system by an explicit system call. should inform the receiving system by an explicit system call.
The characteristics of the links forming an Internet path may vary The characteristics of the links forming an Internet path may vary
greatly. It is therefore difficult to make assumptions about the greatly. It is therefore difficult to make assumptions about the
level or patterns of errors that may occur in the insensitive part of level or patterns of errors that may occur in the corruption
the UDP-Lite payload. Applications that use UDP-Lite should not make insensitive part of the UDP-Lite payload. Applications that use UDP-
any assumptions regarding the correctness of the received data beyond Lite should not make any assumptions regarding the correctness of the
the indicated checksum coverage, and should if necessary introduce received data beyond the position indicated by the Checksum Coverage
their own appropriate validity checks. field, and should if necessary introduce their own appropriate
validity checks.
3.4. IP Interface 3.4. IP Interface
As for UDP, the IP module must provide the pseudo header to the UDP- As for UDP, the IP module must provide the pseudo header to the UDP-
Lite module. The UDP-Lite pseudo header contains the IP addresses and Lite protocol module (known as the UDPLite module). The UDP-Lite
protocol fields of the IP header, and also the length of the IP pseudo header contains the IP addresses and protocol fields of the IP
payload, which is derived from the Length field of the IP header. header, and also the length of the IP payload, which is derived from
the Length field in the IP header.
The sender IP module MUST NOT pad the IP payload with extra octets The sender IP module MUST NOT pad the IP payload with extra octets,
since the length of the UDP-Lite payload delivered to the receiver since the length of the UDP-Lite payload delivered to the receiver
depends on the length of the IP payload. depends on the length of the IP payload.
Larzon, et al. [Page 5]
3.5. Jumbograms 3.5. Jumbograms
The Checksum Coverage field is 16 bits and can represent a checksum The Checksum Coverage field is 16 bits and can represent a Checksum
coverage of up to 65535 octets. This allows arbitrary checksum Coverage value of up to 65535 octets. This allows arbitrary checksum
coverage for IP packets, unless they are Jumbograms. For Jumbograms, coverage for IP packets, unless they are Jumbograms. For Jumbograms,
the checksum can cover either the entire payload (when the Checksum the checksum can cover either the entire payload (when the Checksum
Coverage field has the value zero), or else at most the initial 65535 Coverage field has the value zero), or else at most the initial 65535
octets of the UDP-Lite packet. octets of the UDP-Lite packet.
4. Lower Layer Considerations 4. Lower Layer Considerations
Since UDP-Lite can deliver packets with damaged payloads to an Since UDP-Lite can deliver packets with damaged payloads to an
application that wants them, frames carrying UDP-Lite packets need application that wishes to receive them, frames carrying UDP-Lite
not be discarded by lower layers when there are errors only in the packets need not be discarded by lower layer protocols when there are
insensitive part. For a link that supports partial error detection, errors only in the insensitive part. For a link that supports partial
the Checksum Coverage field in the UDP-Lite header MAY be used as a error detection, the Checksum Coverage field in the UDP-Lite header
hint of where errors do not need to be detected. Lower layers MUST MAY be used as a hint of where errors do not need to be detected.
use a strong error detection mechanism to detect at least errors that Lower layers MUST use a strong error detection mechanism [LINK] to
occur in the sensitive part of the packet, and discard damaged detect at least errors that occur in the sensitive part of the
packets. The sensitive part consists of the octets between the first packet, and discard damaged packets. The sensitive part consists of
octet of the IP header and the last octet identified by the Checksum the octets between the first octet of the IP header and the last
Coverage field. At least the sensitive part would thus be treated in octet identified by the Checksum Coverage field. The sensitive part
exactly the same way as UDP packets. would thus be treated in exactly the same way as for a UDP packet.
Link layers that do not support partial error detection suitable for Link layers that do not support partial error detection suitable for
UDP-Lite, as described above, MUST detect errors in the entire UDP- UDP-Lite, as described above, MUST detect errors in the entire UDP-
Lite packet, and discard damaged packets. The whole UDP-Lite packet Lite packet, and MUST discard damaged packets [LINK]. The whole UDP-
is thus treated in exactly the same way as a UDP packet. Lite packet is thus treated in exactly the same way as a UDP packet.
It should be noted that UDP-Lite would only make a difference to the It should be noted that UDP-Lite would only make a difference to an
application if partial error detection, based on the partial checksum application if partial error detection, based on the partial checksum
feature of UDP-Lite, is implemented also by link layers, as discussed feature of UDP-Lite, is implemented also by link layers, as discussed
above. Obviously, partial error detection at the link layer would above. Partial error detection at the link layer would only make a
only make a difference when implemented over error-prone links. difference when implemented over error-prone links.
5. Compatibility with UDP 5. Compatibility with UDP
UDP and UDP-Lite have similar syntax and semantics. Applications UDP and UDP-Lite have similar syntax and semantics. Applications
designed for UDP may therefore use UDP-Lite instead, and will by designed for UDP may therefore use UDP-Lite instead, and will by
default receive the same full packet coverage. The similarities also default receive the same full packet coverage. The similarities also
ease implementation of UDP-Lite, since only minor modifications are ease implementation of UDP-Lite, since only minor modifications are
needed to an existing UDP implementation. needed to an existing UDP implementation.
UDP-Lite has been allocated a separate IP protocol identifier, XXXX UDP-Lite has been allocated a separate IP protocol identifier, XXXX
[INSERT IANA NUMBER BEFORE PUBLICATION], that allows a receiver to (UDPLite) [INSERT IANA NUMBER BEFORE PUBLICATION], that allows a
identify whether UDP or UDP-Lite is used. A system unaware of UDP- receiver to identify whether UDP or UDP-Lite is used. A destination
Lite will in general return an ICMP Protocol Unreachable error end host that is unaware of UDP-Lite will, in general, return an ICMP
message to the sender. This simple method of detecting UDP-Lite
unaware systems is the primary benefit of having separate protocol Larzon, et al. [Page 6]
identifiers. "Protocol Unreachable" or an ICMPv6 "Payload Type Unknown" error
message (depending on the IP protocol type). This simple method of
detecting UDP-Lite unaware systems is the primary benefit of having
separate protocol identifiers.
The remainder of this section provides the rationale for allocating a The remainder of this section provides the rationale for allocating a
separate IP protocol identifier for UDP-Lite, rather than sharing the separate IP protocol identifier for UDP-Lite, rather than sharing the
IP protocol identifier with UDP. IP protocol identifier with UDP.
There are no known interoperability problems between UDP and UDP-Lite There are no known interoperability problems between UDP and UDP-Lite
if they were to share the protocol identifier with UDP. Specifically, if they were to share the protocol identifier with UDP. Specifically,
there is no case where a potentially problematic packet is delivered there is no case where a potentially problematic packet is delivered
to an unsuspecting application; a UDP-Lite payload with partial to an unsuspecting application; a UDP-Lite payload with partial
checksum coverage cannot be delivered to UDP applications, and UDP checksum coverage cannot be delivered to UDP applications, and UDP
packets that only partially fill the IP payload cannot be delivered packets that only partially fill the IP payload cannot be delivered
to applications using UDP-Lite. to applications using UDP-Lite.
However, if the protocol identifier were to be shared between UDP and However, if the protocol identifier were to have been shared between
UDP-Lite, and a UDP-Lite implementation was to send a UDP-Lite packet UDP and UDP-Lite, and a UDP-Lite implementation was to send a UDP-
using a partial checksum to a UDP implementation, the UDP Lite packet using a partial checksum to a UDP implementation, the UDP
implementation would silently discard the packet, because a implementation would silently discard the packet, because a
mismatching pseudo header would cause the UDP checksum to fail. mismatching pseudo header would cause the UDP checksum to fail.
Neither the sending nor the receiving application would be notified. Neither the sending nor the receiving application would be notified.
Potential solutions to this could have been: Potential solutions to this could have been:
1) explicit application in-band signaling (while not using the 1) explicit application in-band signaling (while not using the
partial checksum coverage option) to enable the sender to learn partial checksum coverage option) to enable the sender to learn
whether the receiver is UDP-Lite enabled or not, or whether the receiver is UDP-Lite enabled or not, or
2) use of out-of-band signaling such as H.323, SIP, or RTCP to 2) use of out-of-band signaling such as H.323, SIP, or RTCP to
convey whether the receiver is UDP-Lite enabled. convey whether the receiver is UDP-Lite enabled.
Anyway, since UDP-Lite has now been assigned its own protocol Since UDP-Lite has been assigned its own IP protocol identifier,
identifier, there is no need to consider the possibility of delivery there is no need to consider this possibility of delivery of a UDP-
of a UDP-Lite packet to an unsuspecting UDP port. Lite packet to an unsuspecting UDP port.
6. Security Considerations 6. Security Considerations
The security impact of UDP-Lite is related to its interaction with The security impact of UDP-Lite is related to its interaction with
authentication and encryption mechanisms. When the partial checksum authentication and encryption mechanisms. When the partial checksum
option of UDP-Lite is enabled, the insensitive portion of a packet option of UDP-Lite is enabled, the insensitive portion of a packet
may change in transit. This is contrary to the idea behind most may change in transit. This is contrary to the idea behind most
authentication mechanisms: authentication succeeds if the packet has authentication mechanisms: authentication succeeds if the packet has
not changed in transit. Unless authentication mechanisms that operate not changed in transit. Unless authentication mechanisms that operate
only on the sensitive part of packets are developed and used, only on the sensitive part of packets are developed and used,
authentication will always fail on UDP-Lite packets where the authentication will always fail for UDP-Lite packets where the
insensitive part has been damaged. insensitive part has been damaged.
The IPSec integrity check (Encapsulation Security Protocol, ESP, or The IPSec integrity check (Encapsulation Security Protocol, ESP, or
Larzon, et al. [Page 7]
Authentication Header, AH) is applied (at least) to the entire IP Authentication Header, AH) is applied (at least) to the entire IP
packet payload. Corruption of any bit within the protected area will packet payload. Corruption of any bit within the protected area will
then result in the discarding of the UDP-Lite packet by the IP then result in the IP receiver discarding the UDP-Lite packet.
receiver.
Encryption is also an issue when using UDP-Lite. If a few bits of an When IPSEC is used with ESP payload encryption, a link can not
encrypted packet are damaged, the decryption transform will typically determine the specific transport protocol of a packet being forwarded
spread errors so that the packet becomes too damaged to be of use. by inspecting the IP packet payload. In this case, the link MUST
Many strong encryption transforms today exhibit this behavior, for provide a standard integrity check covering the entire IP packet and
reasons obvious from a security point of view. There exist encryption payload. UDP-Lite provides no benefit in this case.
transforms, stream ciphers, which do not spread errors in this way
when the damage occurs in the insensitive part of the packet. Encryption (e.g., at the transport or application levels)
may be used. Note that omitting an integrity check can, under
certain circumstances, compromise confidentiality [Bell98].
If a few bits of an encrypted packet are damaged, the decryption
transform will typically spread errors so that the packet becomes
too damaged to be of use. Many encryption transforms today exhibit
this behavior. There exist encryption transforms, stream ciphers,
which do not cause error propagation. Proper use of stream ciphers
can be quite difficult, especially when authentication-checking is
omitted [BB01]. In particular, an attacker can cause predictable
changes to the ultimate plaintext, even without being able to
decrypt the ciphertext.
7. IANA Considerations 7. IANA Considerations
A new IP protocol number, XXXX [INSERT NUMBER BEFORE PUBLICATION], A new IP protocol number, XXXX [INSERT NUMBER BEFORE PUBLICATION],
has been assigned for UDP-Lite. has been assigned for UDP-Lite. The name associated with this
protocol number is "UDPLite". This ensures compatibility across a
wide range of platforms, since on some platforms the "-" character
may not form part of a protocol entity name.
[NOTE, REMOVE BEFORE PUBLICATION] [NOTE, REMOVE BEFORE PUBLICATION]
IANA assignment instruction: IANA assignment instruction:
- The IANA must reserve an IP protocol number for UDP-Lite. The IANA must reserve an IP protocol number for UDP-Lite.
IANA - Please NOTE the name of the registry entry MUST be
"UDPLite", as detailed above.
[END OF NOTE] [END OF NOTE]
Larzon, et al. [Page 8]
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC-768] Postel, J., "User Datagram Protocol", RFC 768 (STD6), [RFC-768] Postel, J., "User Datagram Protocol", RFC 768 (STD6),
August 1980. August 1980.
[RFC-791] Postel, J., "Internet Protocol", RFC 791 (STD5), [RFC-791] Postel, J., "Internet Protocol", RFC 791 (STD5),
September 1981. September 1981.
skipping to change at page 8, line 29 skipping to change at page 13, line ?
Internet Checksum", RFC 1071, September 1988. Internet Checksum", RFC 1071, September 1988.
[RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119 (BCP15), March 1997. Requirement Levels", RFC 2119 (BCP15), March 1997.
[RFC-2460] Deering, S., and R. Hinden, "Internet Protocol, Version 6 [RFC-2460] Deering, S., and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998. (IPv6) Specification", RFC 2460, December 1998.
8.2. Informative References 8.2. Informative References
[Bell98] Bellovin, S.M., "Cryptography and the Internet",
Proceedings of CRYPTO 98, August, 1988.
[BB01] Bellovin, S.M., and M. Blaze, "Cryptographic Modes of
Operation for the Internet", 2nd NIST Workshop on Modes
of Operation, August 2001.
[3GPP] "Technical Specification Group Services and System
Aspects; Quality of Service (QoS) concept and
architecture", TS 23.107 V5.9.0, Technical Specification
3rd Generation Partnership Project, June 2003.
[H.264] Hannuksela, M.M., T. Stockhammer, M. Westerlund. And
D. Singer, "RTP payload Format for H.264 Video", Internet
Draft, Work in Progress, March 2003.
[ILBRC] S.V. Andersen, et. al., "Internet Low Bit Rate Codec",
draft-ietf-avt-ilbc-codec-01.txt, Internet Draft, Work in
Progress, March 2003.
[ISO-14496] ISO/IEC International Standard 1446 (MPEG-4),
"Information Technology Coding of Audio-Visual
Objects", January 2000.
[ITU-H.263] "Video Coding for Low Bit Rate Communication," ITU-T
Recommendation H.263, January 1998.
Larzon, et al. [Page 9]
[ITU-H.264] "Draft ITU-T Recommendation and Final Draft International
Standard of Joint Video Specification",
ITU-T Recommendation H.264, May 2003.
[LINK] Phil Karn, Editor, "Advice for Internet Subnetwork
Designers", Work in Progress, IETF.
[RFC-1889] Schulzrinne, H., Casner, S., Frederick, R., and [RFC-1889] Schulzrinne, H., Casner, S., Frederick, R., and
V. Jacobson, "RTP: A Transport Protocol for Real-Time V. Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", RFC 1889, January 1996. Applications", RFC 1889, January 1996.
[RFC-2026] Bradner, S., "The Internet Standards Process", RFC 2026, [RFC-2026] Bradner, S., "The Internet Standards Process", RFC 2026,
October 1996. October 1996.
[RFC-2402] Kent, S., and R. Atkinson, "IP Authentication Header", [RFC-2402] Kent, S., and R. Atkinson, "IP Authentication Header",
RFC 2402, November 1998. RFC 2402, November 1998.
[RFC-2406] Kent, S., and R. Atkinson, "IP Encapsulating Security [RFC-2406] Kent, S., and R. Atkinson, "IP Encapsulating Security
Payload (ESP)", RFC 206, November 1998. Payload (ESP)", RFC 206, November 1998.
[UDP-LITE] Larzon, L-A., Degermark, M., and S. Pink, "UDP Lite for [RFC-3267] Sjoberg, J., M. Westerlund, A. Lakeaniemi, and Q. Xie,
"Real-Time Transport Protocol (RTP) Payload Format and
File Storage Format for the Adaptiove Multi-Rate (AMR)
and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs",
RFC 3267, June 2002.
[LDP99] Larzon, L-A., Degermark, M., and S. Pink, "UDP Lite for
Real-Time Multimedia Applications", Proceedings of the Real-Time Multimedia Applications", Proceedings of the
IEEE International Conference of Communications (ICC), IEEE International Conference of Communications (ICC),
1999. 1999.
9. Acknowledgements 9. Acknowledgements
Thanks to Ghyslain Pelletier for significant technical and editorial Thanks to Ghyslain Pelletier for significant technical and editorial
comments. Thanks also to Elisabetta Carrara and Mats Naslund for comments. Thanks also to Steven Bellovin, Elisabetta Carrara, and
reviewing the security considerations chapter, and to Peter Eriksson Mats Naslund for reviewing the security considerations chapter, and
for doing a language review and thereby improving the clarity of this to Peter Eriksson for a language review and thereby improving the
document. clarity of this document.
Larzon, et al. [Page 10]
10. Authors' Addresses 10. Authors' Addresses
Lars-Ake Larzon Lars-Ake Larzon
Department of CS & EE Department of CS & EE
Lulea University of Technology Lulea University of Technology
S-971 87 Lulea, Sweden S-971 87 Lulea, Sweden
Email: lln@cdt.luth.se Email: lln@cdt.luth.se
Mikael Degermark Mikael Degermark
Department of Computer Science Department of Computer Science
skipping to change at page 10, line 5 skipping to change at page 13, line ?
Box 920 Box 920
S-971 28 Lulea, Sweden S-971 28 Lulea, Sweden
Email: lars-erik.jonsson@ericsson.com Email: lars-erik.jonsson@ericsson.com
Godred Fairhurst Godred Fairhurst
Department of Engineering Department of Engineering
University of Aberdeen University of Aberdeen
Aberdeen, AB24 3UE, UK Aberdeen, AB24 3UE, UK
Email: gorry@erg.abdn.ac.uk Email: gorry@erg.abdn.ac.uk
Larzon, et al. [Page 11]
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
skipping to change at page 10, line 33 skipping to change at page 13, line ?
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
This Internet-Draft expires June 5, 2003. This Internet-Draft expires December, 2003.
Larzon, et al. [Page 12]
[NOTE, REMOVE BEFORE PUBLICATION]
Document History 02j - This section is intended to assist the AD in
review of the document. It must be deleted by the RFC Editor.
(1) IANA Assignemnet Name chnage UDP-Lite renamed UDPLite to
increase the portability of the code to operating systems that
use the "-" character as a part of the mapping function (i.e.
not allowed in the protocol ID).
Having done this, I now worry a little that this may now divorce
the RFC from the previous published work --- should we also
refer people to UDP-Lite?
(2) Text added to 2nd para, section 3.1 to say pseudo header always
present.
(3) Text added to 2nd para, section 3.1 to say initial checksum value
is zero.
(4) Section 5, added IPv6 text: A destination end host that is
unaware of UDP-Lite will, in general, return an ICMP "Protocol
Unreachable" or an ICMPv6 "Payload Type Unknown" error message
(depending on the IP protocol type).
(5) BSD Code behaviour? This is a protocol problem with a BSD
implementation, not a spec fault.
(6) Examples added of applications
(7) Examples of systems that would use it
(8) Security issues (text requested by IESG).
(9) Minor NiTs with written English corrected.
(10) Introduction starts rather strangely - can we fix this?
(11) Security AD Text Revised, and now OK.
(12) Revised security note:
When IPSEC is used with ESP payload encryption, there is no
visibility of the transport header, and therefore a link can not
determine which transport layer protocol is used, and would not be
able to determine the value of the Checksum Coverage field. UDP-Lite
provides no benefit in this case, and the link MUST provide a
standard integrity check.
[END OF NOTE]
 End of changes. 

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