Re: [mpls] Two new drafts on (micro-)BFD over MC-LAG interfaces

[Manav Bhatia <[e-mail]>]

I believe it had to do with multicast datapath (especially link local)
being different from the unicast datapath in most routers. Using link local
multicast IP addresses may not necessarily guarantee Unicast IP
reachability.

When writing 7130 we spent quite a bit of time ensuring that we dont carve
out a special data path for the micro-BFD packets. Using link local would
have made it a lot simpler.

And this is where i think the current proposal is flawed -- they use link
local multicast to ensure IP unicast reachability which is incorrect.

Cheers, Manav

On Thu, Apr 7, 2016 at 11:16 PM, Mach Chen <[e-mail]> wrote:

> Hi Greg and all,
>
>
>
> I just have quick review on the drafts. If my understanding is correct,
> the idea is to use multicast destination address other than unicast address
> when  sending BFD packets over LAG links. And actually this idea has been
> proposed in https://tools.ietf.org/html/draft-chen-bfd-interface-00 (the
> predecessor of RFC 7130). And at that time, the co-authors of RFC 7130 did
> discuss the idea of using multicast destination address, but for some
> reason I forget now(I may need to reiterate the discussions on the
> archive), the idea was abandoned, although I still think multicast
> destination address is a smart idea.
>
>
>
> Best regards,
>
> Mach
> ------------------------------
> *From:* Rtg-bfd [[e-mail]] on behalf of Gregory Mirsky [
> [e-mail]]
> *Sent:* Tuesday, April 05, 2016 6:16
> *To:* [e-mail]; [e-mail]
> *Cc:* [e-mail];
> [e-mail]; [e-mail]; Alia Atlas (
> [e-mail])
> *Subject:* Two new drafts on (micro-)BFD over MC-LAG interfaces
>
> Dear All,
>
> two new drafts, related to RFC 7130, were published before the meeting:
>
> ·         BFD on MC-LAG interfaces in IP network
> <https://tools.ietf.org/html/draft-tanmir-rtgwg-bfd-mc-lag-ip-00>
>
> ·         BFD on MC-LAG interfaces in IP/MPLS network
> <https://tools.ietf.org/html/draft-tanmir-rtgwg-bfd-mc-lag-mpls-00>
>
>
>
> Greatly appreciate your reviews, comments, questions and suggestions.
>
>
>
> Regards,
>
>         Greg
>