On 7 Mar 2024, at 10:39, Jethro Binks <[log in to unmask]> wrote:

> In our case, we are one AS throughout, we don't have the collegiate fun you guys have, so no need for MSDP internally between bits of our network.

Just to be clear (as it may be pertinent to others looking at this), our backbone is one AS and peers with Janet; the Colleges may be separate ASs, if they choose to use BGP to connect to us.

In addition, however, our Data Centre Network is a separate AS (actually about six ASs because of historical nonsense, as well as VMware NSX-T), central wireless infrastructure is separate, and our fabric sites are separate ASs (each physical site corresponds to a separate fabric, where they're in use) so we have lots of ASs and the need for inter-domain multicast even without the federated College environment, just because of the scale and technical requirements of the technology (Cisco SDA, Aruba fabric stuff and Cisco ACI in the data centre).

It's possible people running fabrics will end up hitting the same issues: even if they have a single fabric for the organisation, the handoff to the upstream network is often done with eBGP, so you might end up with 2/3 ASs at least (backbone/border, campus and data centre network).

I just did a count and we have 48 ASs internally and they only seem to be going up!

  - Bob


-- 
Robert Franklin <[log in to unmask]> / (+44 1223 7) 48479
University Information Services: Network Systems, University of Cambridge

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