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Draft-hares-idr-update-attrib-low-bits-fix-01

Draft-hares-idr-update-attrib-low-bits-fix-01. Sue Hares and John Scudder . Topics . What change is Why Changed Example of what broke What’s seen in Wild What broke . RFC4271 section 4.3 . 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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Draft-hares-idr-update-attrib-low-bits-fix-01

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  1. Draft-hares-idr-update-attrib-low-bits-fix-01 Sue Hares and John Scudder

  2. Topics • What change is • Why Changed • Example of what broke • What’s seen in Wild • What broke

  3. RFC4271 section 4.3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attr. Flags |Attr. Type Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Original Text: The lower-order four bits of the Attribute Flags octet are unused. They MUST be zero when sent and MUST be ignored when received Corrected Text: The lower-order four bits of the Attribute Flags octet are unused. They MUST be zero when originated or sent. When received, any MUST be accepted and ignored.

  4. RFC4271 Section 4.3 • Disagreement on what when sent means. • The issue has been that one school of thought considers that "when sent" means when originated. • Another holds that "when sent" means when originated or propagated. • This draft takes the second approach of "when sent" being when originated or propagated.

  5. Scenario that broke LANL AS100 JunOS LANL: originated routes with illegal flags (1 MBZ bit set to 1) JunoS – passed along AS200, AS300 – dropped session because of bit set (failed to ignore when received) AS 400: unaffected (ignored) Flags indicate Update message AS200 OpenBGPd AS300 OpenBGPd AS400 Red flags – dropped session Blue – working Excerpted from presentation by Jeff Wheeler jsw@inconcepts.bits

  6. Cases seen in Wild. • always ignore bits received, and always send zero (originated or propagated); • always ignore bits received, always send zero bits (originated), and propagate what was received; • if non-zero bits are received, drop the peering session; • by special condition (policy) handle set bits or set bits, and propagate;and • always sets bits under special conditions, and propagates bits.

  7. Discussion • What next (led by Stewart Bryant)

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