Re: [Idr] BGP Auto-Discovery Protocol State Requirements

Robert Raszuk <> Fri, 19 March 2021 13:49 UTC

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From: Robert Raszuk <>
Date: Fri, 19 Mar 2021 14:49:05 +0100
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To: Jeffrey Haas <>
Cc: Tony Przygienda <>, "" <>, "Acee Lindem (acee)" <>
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Subject: Re: [Idr] BGP Auto-Discovery Protocol State Requirements
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> There's some discussion in the draft about what transport layer we use, and
> a few of the headaches.  For BGP auto-discovery, the major implication is
> how wide your want your messages to travel.

And this is precisely the fundamental point we would need to agree on.

Currently the answer is any transport. I recommended to limit it *only* to
L2 links (physical or emulated).

For the DC use case I think this is more then enough.

And if you take that as a base then to automatically establish BGP session
is not that hard. In fact you may not need any protocol at all.

*All you need is two steps: *

*Step 1 - Find out who is on your link (directly via ICMP or by looking at
likely already running LLDP or CDP :)*
*Step 2 - Among peers discovered in step 1 for each address you check if he
is listening on 179. If so you send him an OPEN. *


Some suggested to add this info to LLDP from step 1 which is not bad idea
either. But maybe IDR has no power to recommend additions to LLDP.

The above works fine for p2p and p2mp ethernets just fine. You can bring up
BGP for your DC core and you can bring BGP to your computes from TOR or
virtual instances running on computes as long as they talk
direectly to the underlay LAN.

- - -

Side comment: When we worked on single side BGP we had very similar
discussions. But large SP was very clear with the requirements ... If I
enable auto peering on my LAN towards customer all I care to accept his
sessions is MD5 match.