Alia Atlas' Discuss on draft-ietf-bfd-seamless-base-09: (with DISCUSS and COMMENT)
"Alia Atlas" <akatlas@gmail.com> Mon, 02 May 2016 22:14 UTC
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From: Alia Atlas <akatlas@gmail.com>
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Subject: Alia Atlas' Discuss on draft-ietf-bfd-seamless-base-09: (with DISCUSS and COMMENT)
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Date: Mon, 02 May 2016 15:14:46 -0700
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Alia Atlas has entered the following ballot position for draft-ietf-bfd-seamless-base-09: Discuss When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-bfd-seamless-base/ ---------------------------------------------------------------------- DISCUSS: ---------------------------------------------------------------------- a) In Sec 7.2.3: "If the SBFDReflector is generating a response S-BFD control packet for a local entity that is in service, then "state" in response BFD control packets MUST be set to UP." So far, it looked like the SBFDReflector only sends BFD control packets in response to receiving such packets from SBFDInitiators. This paragraph (not just copied) does not clearly describe the desired behavior. If the monitored local entity is "temporarily out of service", does the SBFDReflector respond back to the SBFDInitiator with 2 BFD control packets - one indicating UP (as a MUST) and then the next indicating ADMINDOWN? Is the SBFDReflector expected to store a list of active SBFDInitiators and proactively send BFD control packets indicating ADMINDOWN? Please clarify in non-trivial detail. b) Appendix A: The looping problem is nicely defined but the text still discusses three potential solutions; clearly the use of the D bit has been chosen. It would be much nicer to have the justification in line, but for this discuss - the unselected alternatives don't belong. c) Sec 7.2.1: " S-BFD packet MUST be demultiplexed with lower layer information (e.g., dedicated destination UDP port, associated channel type)." Please add a clear reference to [draft-ietf-bfd-seamless-ip] here to show where to find the dedicated UDP port for S-BFD; I think this or some other mechanism needs to be a normative reference, because I don't see how one could implement S-BFD without this knowledge. In particular, since the format for an S-BFD control packet is exactly the same as for BFD and since only this demultiplexing with lower layer information is used to tell the difference between S-BFD and BFD packets, this document requires more specifics. ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- 1) In the last paragraph of Sec 4.2: " Even when following the separate discriminator pool approach, collision is still possible between one S-BFD application to another S-BFD application, that may be using different values and algorithms to derive S-BFD discriminator values. If the two applications are using S-BFD for a same purpose (e.g., network reachability), then the colliding S-BFD discriminator value can be shared. If the two applications are using S-BFD for a different purpose, then the collision must be addressed. How such collisions are addressed is outside the scope of this document." Sec 4.1 talks about the need for the S-BFD Discriminator to be unique within an Administrative Domain. I don't see any details of that addressed here. What is addressed here seems to be the case for multiple S-BFD discriminators applying to the same node - which is specifically discouraged at the end of Sec 3. Rather than simply describing the issue as "outside the scope of this document", please either describe it as "future work and multiple S-BFD discriminators is discouraged" or add a reference. 2) In Sec 6.1: "bfd.SessionType:" is defined but the only possible values are for SBFD. Is it possible for a BFD session to still use the same bfd structure? I don't see a value for SessionType there; I'd expect to see at least a value for the original BFD session and possible an undefined or unspecified value for future proofing.
- Alia Atlas' Discuss on draft-ietf-bfd-seamless-ba… Alia Atlas
- Alia Atlas' Discuss on draft-ietf-bfd-seamless-ba… Alia Atlas
- Re: Alia Atlas' Discuss on draft-ietf-bfd-seamles… Carlos Pignataro (cpignata)
- Re: Alia Atlas' Discuss on draft-ietf-bfd-seamles… Alia Atlas
- Re: Alia Atlas' Discuss on draft-ietf-bfd-seamles… Alia Atlas
- Re: Alia Atlas' Discuss on draft-ietf-bfd-seamles… Carlos Pignataro (cpignata)
- Re: Alia Atlas' Discuss on draft-ietf-bfd-seamles… Carlos Pignataro (cpignata)