Question about experiences with BGP remote-AS

Tyler Conrad tyler at
Fri May 5 19:14:50 UTC 2017

Neighbor x.x.x.x local-as {whateverasn} no-prepend replace-as

On Friday, May 5, 2017, LF OD <bz_siege_01 at> wrote:

> We have a number of small routers in co-lo sites that peer with B2B
> partners. As more of our partners move to cloud, we are considering a
> consolidation effort and putting all of  our peering routers in a cloud
> exchange site on a single HA pair of routers. Now, each existing B2B
> peering router uses a unique private ASN to EBGP peer with partners and
> they, in turn, EBGP peer with our extranet perimeter ASNs for security
> vetting and other stuff.
> We looked for a medium-density router (or L3-switch) that can replace
> multiple small routers (b2b-only, no internet), but we need to retain all
> of our existing ASNs and peerings. As it turns out, there are many routers
> that can do VRFs but you cannot put a unique ASN on each VRF so replicating
> the old environment isn't quite that straightforward. The BGP remote-as
> looks to be a possible alternative solution, but we've never used it in
> production and we are unsure of the caveats. Taken at face value, it looks
> like we can mimic the multi-router/unique-ASN environment we have today on
> a single platform. However, networking is rarely as smooth as that so I'm
> asking some of the BGP gurus... what are the pros/cons of doing using
> remote-as? If anyone here uses it extensively, we could really use some
> feedback if you run into challenges or hidden surprises that we wouldn't
> normally think of beforehand.
> Thanks in advance!

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