Re: Distributed Router Fabrics

[Tom Beecher <beecher () beecher cc>]

Again, it depends.

DFs at the edge as you're talking about are tricky. We worked on some
designs a couple years ago. FIB management can become really tricky, with a
lot of big peers and/or connections to the DFZ. If you do it wrong you can
get tricky hotspotting or bouncing issues with your N/S traffic.

It's doable of course, but in many circumstances I think these make the
most sense down in the aggregation layers of a design.

On Thu, Dec 26, 2024 at 9:30 PM Mike Hammett <nanog () ics-il net> wrote:

> *nods* Yeah, I knew that's how a traditional chassis worked. In a
> distributed setup, you have the option for a single "line card", which
> obviously doesn't happen in the traditional chassis world.
>
>
> I do see in a DDCv2 document where they briefly mention 2 compute boxes,
> so now that makes sense. I had to look up some of the acronyms because the
> document didn't define them within itself.
>
>
>
> -----
> Mike Hammett
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> ------------------------------
> *From: *"Randy Bush" <randy () psg com>
> *To: *"Mike Hammett" <nanog () ics-il net>
> *Cc: *"NANOG" <nanog () nanog org>
> *Sent: *Thursday, December 26, 2024 4:51:45 PM
> *Subject: *Re: Distributed Router Fabrics
>
> > > In a distributed fabric, where is the traditional control plane run?
> > > Say I've got 100 BGP sessions of upstream,peer, and downstream across
> > > ten routers. Is each pizza box grinding this out on its own, or is the
> > > work done on the x86 box mentioned in the larger installations?
> >
> > one way to think of it is that each pizza box (customer facing ports)
> > recognizes control plane messages (e.g. port 179) and "punts" them to
> > the control plane box, aka routing engine.
>
> fwiw, that is pretty much what line cards on a big-box fabric do, punt
> to the RE.
>
> randy