March HIP Checksum Coverage draft-dawkins-hip-checksum-coverage-00 XingFeng Jiang, Philip Matthews, Spencer Dawkins IETF 70 – December 2007 Vancouver, British Columbia

March How we got here P2PSIP HIPHOP proposes HIP-layer forwarding Other proposals also have this concept –Draft-ietf-hip-rvs and draft-ietf-hip-nat-traversal Looking at HIP 16-bit checksum –Includes transport pseudo-header –Pseudo header updated when packet forwarded, thus checksum must be updated at each hop.

March Proposal Remove transport pseudo-header from HIP checksum calculation –No need to update checksum when forwarding –Pseudo-header no longer needed for HIP Draft also proposed to change checksum to CRC32c – dropping this idea after feedback –This change requires larger checksum field –Would change common HIP/SHIM6 header format –Breaks incremental checksum update

March Discussion Is proposed HIP checksum redundant? –Signature and HMAC also cover HIP header + HIP parameters. –When we run HIP over UDP, UDP checksum also covers HIP packet. –Always set HIP checksum to zero? HIP-HOP thinking about HIP msgs with bodies –i.e. NextHeader field <> NoNext Header –Not the first to propose this, either –Should HIP checksum cover body?