IX ARP Timeout

Thu Jan 28 09:20:22 UTC 2016

Unless your IX has an unusual amount of churn, a four hour timeout really shouldn’t be a problem.

Stale records really shouldn’t be a problem as they should get overwritten with gratuitous ARPs when needed.

OTOH, having the ARP be somewhat sticky can not only reduce broadcast traffic, but also preserve visibility of what was when trying to troubleshoot.

I’m trying to think of a downside to a 400 second ARP timeout for an XP and I guess I’m short of creativity at the moment because I’m coming up blank.

Owen

> On Jan 27, 2016, at 19:02 , Mike Hammett <nanog at ics-il.net> wrote:
> 
> 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. 
> 
> 
> 
> 
> ----- 
> Mike Hammett 
> Intelligent Computing Solutions 
> http://www.ics-il.com 
> 
> Midwest-IX 
> http://www.midwest-ix.com 