[SCION] 2nd BR in one AS

Juan A. García-Pardo juan.garcia at inf.ethz.ch
Fri Oct 14 09:31:34 CEST 2022

Hi Alexander,

> Hello team,
> Is there a way to configure more than one Border Router for one AS ?
> I’m trying to configure two, kind of redundant setup, and establish
> intra-AS link between them.
Yes, you can configure more than one border router per AS. The restriction
is that they all have to contain distinct inter-AS interfaces. For
instance, you can use two border routers to communicate two user ASes of
yours, using a CHILD/PARENT "link_to" field in the "topology.json"
configuration file. You will have to add a new interface number under
"border_routers" -> "interfaces".

> What should be LinkTo type in topology.json for intra-AS connection ?
SCION (and scionlab) doesn't support intra-AS connectivity/configuration,
only inter-domain.

I tried to configure it as a PEER, and although BorderRouter service
> accepts it, and lists it as an available interface but I don’t see any
> attempts to initiate BFD session over that link.
Hmm PEER, in particular, has the extra problem that is not yet supported in
the open-source implementation of the protocol, which is what we use in
scionlab. We would like to implement it soon, but we  still haven't found
the resources for it.

Please don't hesitate to ask more questions if the setup is not clear, of
if you have a different need for it.
Thanks and best regards,

Juan A.

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