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Re: [Idr] BGP Auto discovery - L2 liveliness??

Robert Raszuk <robert@raszuk.net> Fri, 20 July 2018 17:20 UTC

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From: Robert Raszuk <robert@raszuk.net>
Date: Fri, 20 Jul 2018 19:20:46 +0200
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To: "Acee Lindem (acee)" <acee=40cisco.com@dmarc.ietf.org>, lsvr@ietf.org
Cc: "Rajiv Asati (rajiva)" <rajiva@cisco.com>, idr wg <idr@ietf.org>
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Subject: Re: [Idr] BGP Auto discovery - L2 liveliness??
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Acee,

I have a comment on this section 6 and subsequent section 5.2.2 of the
document you quoted:

Link Hello are proposed to detect the L2-L2.5-L3 liveness. Well there is a
lot of real life issues with link liveness appearing sporadically and only
at some specific packet sizes. The Hello of fixed size of 25 octets will
not detect it. A sweep size is a must.

That perhaps will not likely appear in p2p fiber - however if someone is
trying to use emulated L2 links as part of DC infra it may very well be the
case.

Thx,
R.



On Fri, Jul 20, 2018 at 7:02 PM, Acee Lindem (acee) <
acee=40cisco.com@dmarc.ietf.org> wrote:

> Hi Rajiv,
> This function is described in section 6 of https://www.ietf.org/id/draft-
> ymbk-lsvr-lsoe-01.txt. I guess you are questioned whether it should be a
> requirement of this mechanism.
>
> Thanks,
> Acee
>
> On 7/20/18, 11:43 AM, "Rajiv Asati (rajiva)" <rajiva@cisco.com> wrote:
>
>
>     Could someone please explain - How is L2 liveliness important for
> auto-discovery between 2 directly connected BGP neighbors (referring to the
> topology shown yesterday)? Or is it really meant to benefit the peering
> relationship (once established) - bring down the peer if L2 fails or vice
> versa?
>
>     Or is it meant to benefit the (tenant/services) traffic (past bgp NLRI
> exchange) ? Likely not, since  (tenant/services) traffic may be L3 (or
> MPLS), and L2 liveliness would not be sufficient (after all, L2 can be
> working, while L3 might not or MPLS might not).
>
>     Cheers,
>     Rajiv
>
>
>
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