On 2019-03-31, Remi Locherer <remi.loche...@relo.ch> wrote: > On Sun, Mar 31, 2019 at 01:09:06PM +0200, Claudio Jeker wrote: >> On Fri, Mar 29, 2019 at 08:36:26AM +0100, open...@kene.nu wrote: >> > I forgot to add to my previous email. One thing that could be useful >> > in this case is to mimic the Cisco option "neighbor x.x.x.x >> > remove-private-as" which removes any private ASes from the path on any >> > updates to a peer. Just throwing it out there, cant be a very >> > difficult option to implement I guess? >> >> I think changing the AS PATH is a bad thing, removing elements from your >> AS path has a major impact on the route selection and opens doors for >> routing loops. In general I will only add features like 'as-override' when >> there is a clear reason why it is needed. >> So my question is, why do you need to use private AS numbers in your >> internal network? > > It's common to use private AS numbers in data center networks for Clos > topologies (one AS number per leaf switch and one for all spine switches > because of ECMP). > > Private AS numbers are also used for large DMVPN deployments.
Also if you have a downstream with two connections to your network, that isn't eligible to get a public ASN (e.g. doesn't have a second upstream provider).
