IX ARP Timeout

Thu Jan 28 11:44:28 UTC 2016

Hey,

> So I'm looking at the policies, recommended configurations, etc. of other IXes. We try to model a lot of ourselves on what the Europeans do (even if we come up short in some areas). I was reading through the AMS-IX guide.
>
> https://ams-ix.net/technical/specifications-descriptions/config-guide#3.1
>
> They recommend a four hour ARP timeout. Thoughts? Seems a bit excessive, but I don't have over 700 networks on my IX. That said, I don't have over 700 members on my IX generating a ton of ARP traffic, so I'm probably fine recommending a smaller value.
>
> I understand it's a balance between stale records and ARP volume. Just trying to gauge what the community thinks.

I don't think it matters much and at any rate you can't enforce it.
Someone more relevant is that MAC timeout is greater than ARP timeout.
And on IXP even this is not very important, provided no one is static
routing.
On environments I do control, I tend to configure ARP timeout under
300s, as usually MAC timeouts are 300s. By default Cisco is 4h, JunOS
is 20min, Linux is 60s.

-- 
  ++ytti