Subject: Mirja Kühlewind's No Objection on draft-ietf-bfd-seamless-ip-04: (with COMMENT)

From: "Mirja Kuehlewind" <[email-masked]>
Date: Tue, 03 May 2016 02:46:26 -0700

Mirja Kühlewind has entered the following ballot position for
draft-ietf-bfd-seamless-ip-04: No Objection

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COMMENT:
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This part is unclear to me:
"It is, however, possible for an
   SBFDInitiator to carefully set "your discriminator" and TTL fields to
   perform a continuity test towards a target, but to a transit network
   node and not to the target itself. [...] 
   This also requires S-BFD control packets not be dropped by the
   responder node due to TTL expiry.  Thus implementations on the
   responder MUST allow received S-BFD control packets taking TTL expiry
   exception path to reach corresponding reflector BFD session."

You basically perform a traceroute with (S-)BFD, right? Why do you need
the last sentence? Wouldn't it be okay, if the packet get dropped by the
responder, to simply re-send with a higher TTL?

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From: "Carlos Pignataro (cpignata)" <[email-masked]>
Date: Tue, 3 May 2016 09:52:50 +0000

Hi Mirja,

Thanks for the question, please see inline. 

Thumb typed by Carlos Pignataro.
Excuze typofraphicak errows

> On May 3, 2016, at 05:46, Mirja Kuehlewind <[email-masked]> wrote:
> 
> You basically perform a traceroute with (S-)BFD, right?

Almost. We are performing an S-BFD-aware traceroute with S-BFD. 

> Why do you need

No. Basically we need the router to process the pocket as S-BFD (i.e. Intercept it for processing on TTL expiry). Otherwise, we would get an ICMP back while what we are after is an S-BFD back. 

Thanks!

Carlos.