RE: Opinions on Arista for BGP?

[Adam Thompson <athompson () merlin mb ca>]

TL;DR: Yes, go ahead, they’re good, we like them.

I won’t say they’re perfect, but we’re using them at the edge (two of them in a hybrid core/edge model right now, 
even!) and I would happily endorse them for edge routers.  Their BGP stack hasn’t put up any major roadblocks for us so 
far (at least, that weren’t, ahem, self-inflicted).  We’ve had 1 incident in the last ~2 years where a stuck route on 
one router needed a full reboot to clear out, following a partial outage - that’s the worst thing I can remember right 
now.

Don’t know if you know this already or not, so making it clear:  the one thing to beware of IMO, compared to e.g. a 
high-end Juniper MX960-style system where you can turn every single feature on without caring, is that the Aristas can 
do almost anything you can dream of… but not necessarily all at the same time on the same box, no matter which model 
you’re looking at.
So if you use it as an edge router?  Fine.  As a VXLAN gateway?  Fine.  As a core router or switch with every kind of 
accounting turned on?  Fine.  All of those things simultaneously?  Maaaaaybe.  It’ll be decision time for which 
specific, individual sub-features you can live without.  But you’re paying 1/10th (probably less!) of what you would 
for an MX960, so there you go.

If this helps, they’re similar to the Cisco Nexus platform in this regard, e.g. if you enable and use every single 
“Feature” on the fixed-configuration Nexuses you’ll start running out of hardware configuration resources to enable 
them long before you can finish configuring or using all those features.

This is something your Arista SE can go through with you in excruciating detail (keyword: “TCAM Profile”), if you think 
you might be veering into that territory.  After lots of iterations, and a new software release or two, our all-in-one 
boxes (7280SR2K) do more or less everything we want them to.  (Apparently we aren’t typical Arista customers.  Go 
figure.)  If you want to do BGP and MLAG at the same time on the same box, get your SE involved from the start.

For anyone not trying to overload the platform or do too much “weird” stuff, it should be a quick and easy deployment 
producing much happiness.

-Adam


Adam Thompson
Consultant, Infrastructure Services
[MERLIN]
100 - 135 Innovation Drive
Winnipeg, MB, R3T 6A8
(204) 977-6824 or 1-800-430-6404 (MB only)
athompson () merlin mb ca<mailto:athompson () merlin mb ca>
www.merlin.mb.ca<http://www.merlin.mb.ca/>

From: NANOG <nanog-bounces+athompson=merlin.mb.ca () nanog org> On Behalf Of David Hubbard
Sent: Thursday, March 31, 2022 8:10 AM
To: nanog () nanog org
Subject: Opinions on Arista for BGP?

Hi all, would love to get any current opinions (on or off list) on the stability of Arista’s BGP implementation these 
days.  Been many years since I last looked into it and wasn’t ready for a change yet.  Past many years have been IOS XR 
on NCS5500 platform and Arista everywhere but the edge.  I’ve been really happy with them in the other roles, so am 
thinking about edge now.  I do like and use XR’s RPL, and prefix/as/community/object sets, but we can live without via 
our own config management if there aren’t easy equivalents.  No fancy needs at all, just small web server networks, so 
just need reliable eBGP and internal OSPF/OSPFv3.

Thanks,

David