Folks –
I apologize for the lateness of my comments – I don’t consistently track BIER
WG. Some of what I say below would certainly have been more beneficial if
provided earlier.
Nevertheless..
Regarding the proposal for new IGP Extensions for advertising BIER BFD
information:
I am troubled at the idea of having the IGP advertise information which
includes the BIER Bit-String representing the relevant BFR-IDs. This string
(defined in RFC 8296) can potentially be up to 4K bits (512 bytes) long.
This is a lot of information for the IGPs to carry – and is particularly
troublesome for IS-IS where it exceeds the carrying capacity of a single TLV
(max 255 bytes).
As a more minor point, the presence of the RESERVED field is inappropriate for
IS-IS. This is commonly done in OSPF to preserve 4 byte field alignment, but
this is useless in IS-IS and only serves to bloat the TLV size unnecessarily.
In a larger context, the only previous use of the IGPs to advertise BFD
discriminators that I am aware of was done in support of S-BFD (RFC 7883). To
my knowledge, implementations have not made use of this extension – perhaps in
part because assignment of discriminators based on information in an IGP
database has not proved appealing – which calls into question why we should do
this here.
NOTE: I am happy to hear feedback from others that RFC 7883 is in fact being
used.
Finally, I ask whether any implementation of this draft – even as a POC – has
been done? If so, what has been learned?
In general, I am concerned that in the absence of implementation experience we
may be standardizing things prematurely.
Thanx for listening to my very late remarks.
Les
From: [email protected] <[email protected]>
Sent: Tuesday, June 25, 2024 12:25 AM
To: [email protected]; [email protected]
Subject: [Bier] Call for review for draft-ietf-bier-bfd
Hi,
The draft-ietf-bier-bfd passed last call in BIER WG.
We'd like to get more review in BFD WG:
https://datatracker.ietf.org/doc/draft-ietf-bier-bfd/
Comments and suggestion welcomed, please send your comments before 9th, July.
And please volunteer if you want to be the shepherd of this draft.
Thank you!
Best regards,
Sandy
