Re: BFD WG adoption for draft-haas-bfd-large-packets

"Albert Fu (BLOOMBERG/ 120 PARK)" <> Mon, 29 October 2018 17:38 UTC

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Date: Mon, 29 Oct 2018 17:38:32 -0000
From: "Albert Fu (BLOOMBERG/ 120 PARK)" <>
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Subject: Re: BFD WG adoption for draft-haas-bfd-large-packets
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Hi Les,

> Jeff/Albert -
> Given the MTU issue is associated with a link coming up - and the use of Echo would allow the problem to be detected and prevent the BFD session from coming up - 
> and you are acknowledging that the protocol allows padded Echo packets today ...
> is there really a need to do anything more?
>    Les

Actually, all the issues we have observed were not associated 
with link going up. The MTU issues occurred after OSPF/BGP had 
established adjacency without any events on the routers. 
ospf/BGP hellos/keepalives continued to be transmitted fine (small
packet size), but applications sending max size packets over the 
link would time out and fail. 

Hence, I mentioned several times that this issue is rather time 
consuming to troubleshoot, as the cause is with the Telco network
and outside of our control and we do not see any alarms.

I did also look at BFD echo mode. As Jeff indicated, this is not 
widely deployed (among the vendors we use, only one supports it).