Partial Checksums - Pointers to the Issues

• UDP-Lite:
  • L-A. Larzon, M. Degermark, S. Pink, L-E. Jonsson (editor), and G. Fairhurst (editor). The UDP-Lite Protocol. draft-ietf-tsvwg-udp-lite-01.txt, work in progress, December 2002.
    "This document describes the UDP-Lite protocol, which is similar to UDP [RFC-768], but can also serve applications that in error-prone network environments prefer to have partially damaged payloads delivered rather than discarded... The security impact of UDP-Lite is related to its interaction with authentication and encryption mechanisms."

  • The IESG Discussion of draft-ietf-tsvwg-udp-lite, in progress.

• DCCP:
  • Eddie Kohler, Mark Handley, Sally Floyd, and Jitendra Padhye, Datagram Congestion Control Protocol (DCCP), draft-ietf-dccp-spec-03.txt, internet-draft, work in progress. From Section 18.1 on "CSlen and Partial Checksumming":
    "Many of the applications that we envisage using DCCP are resilient to some degree of data loss, or they would typically have chosen a reliable transport. Some of these applications may also be resilient to data corruption---some audio payloads, for example. These resilient applications might prefer to receive corrupted data than to have DCCP drop a corrupted packet... Corrupted packets do not need to cause as strong a reduction in transmission rate as the congestion response would dictate (so long as the DCCP header and options are not corrupt)... In addition, partial checksums do not co-exist well with IP-level authentication mechanisms such as IPsec AH, which cover the entire packet with a cryptographic hash... It remains to be seen whether [partial checksums] are useful in practice."

  • Eddie Kohler, Mark Handley, and Sally Floyd, Designing DCCP: Congestion Control Without Reliability, under submission. From Section 4.4 on Partial checksums:
    "Because DCCP is a congestion-controlled transport protocol, some of the design issues for adding partial checksums to DCCP are more complex (and perhaps more compelling) that the issues with UDP... We note that the usefulness of partial checksums remains to be determined."

  • Sally Floyd, Re: [dccp] dccp spec review (Rescorla) email to the dccp mailing list, June 2003.
    "Partial checksums: ... There are a number of issues here:
    (1) Are bit errors sufficiently frequent in the current Internet to make partial checksums worth the trouble?...
    (2) If bit errors aren't sufficiently frequent in the current Internet, would we like to enable future link level technologies that can be just a touch more relaxed about allowing bit errors, or not?"

• Corruption Notification:
  If the Internet architecture included mechanisms for corruption notification from link layers to transport end nodes, this would affect some of the discussion in DCCP regarding partial checksums.

• Link Technologies Delivering Corrupted Data to IP layer.

Return to [Sally Floyd].
Last modified: July 2003.