Santosh:

Hi!

There are 2 more things (Major) that I need you to address.  Sorry, I
almost forgot.

(A) Please take a look at the SecDir comments here [1].

[1] 
https://mailarchive.ietf.org/arch/msg/secdir/o7CSlWeRPh4-BZBTI_eDyoBM7ak



(B)

During the IESG review of draft-ietf-isis-sbfd-discriminator the question
came up about how the mapping of S-BFD discriminators (advertised by IS-IS
in that draft, but there are also similar OSPF and L2TP drafts) to
specific applications/entities is to be done.  This conversation ended up
in me placing a DISCUSS on that document [2].

The problem is that draft-ietf-isis-sbfd-discriminator (and the OSPF and
L2TP drafts) declare the mapping out of scope. *AND*  This document
(draft-ietf-bfd-seamless-base) says this in Section 3. (Seamless BFD
Overview):

   An S-BFD module on each network node allocates one or more S-BFD
   discriminators for local entities, and creates a reflector BFD
   session.  Allocated S-BFD discriminators may be advertised by
   applications (e.g., OSPF/IS-IS).  Required result is that
   applications, on other network nodes, possess the knowledge of the
   mapping from remote entities to S-BFD discriminators.  The reflector
   BFD session is to, upon receiving an S-BFD control packet targeted to
   one of local S-BFD discriminator values, transmit a response S-BFD
   control packet back to the initiator.

This text reads to me that S-BFD is expecting ("Required result") the
mapping to be somehow provided by the "applications (e.g., OSPF/IS-IS)".
Note that one possible interpretation is not for OSPF/IS-IS to "know"
anything about S-BFD discriminators/entities, but to transport that
information (similar to transporting discriminators).  I can see at least
one relevant use case (in draft-ietf-bfd-seamless-use-case) that seems to
require the ability to distinguish and map:  Section 3.8. (Multiple BFD
Sessions to Same Target).

The point to address is this: what is the expectation (from the S-BFD
point of view) with respect to the mapping?

Answering may require a WG-wide discussion.  Depending on the answer,
there may be obvious effects (and work needed) in the isis, ospf and
l2tpext WGs, so please (with the help of the chairs) work with them.


Thanks!

Alvaro.

[2] 
https://datatracker.ietf.org/doc/draft-ietf-isis-sbfd-discriminator/ballot/

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