[atlas] Probe on a /31 or /32 IPv4 network

"(or we can use proxy ARP on the router if it becomes a problem)."

You're a braver man than I. 
Personally, the prospect of troubleshooting proxy-arp at 3 am doesn't sound like much fun. 
-James

-----Original Message-----
From: ripe-atlas-bounces at ripe.net [mailto:ripe-atlas-bounces at ripe.net] On Behalf Of Baptiste Jonglez
Sent: Friday, August 15, 2014 12:07 AM
To: ripe-atlas at ripe.net
Subject: Re: [atlas] Probe on a /31 or /32 IPv4 network

On Fri, Aug 15, 2014 at 06:23:09AM +0200, Mikael Abrahamsson wrote:
> On Thu, 14 Aug 2014, Baptiste Jonglez wrote:
> 
> >Using a gateway that is not on the same subnet doesn't sound very 
> >nice, but again, the goal is to avoid wasting precious IPv4 space.
> 
> What router platform are you using upstream from the probe? Doing a 
> /32 per vlan(ie sharing a larger subnet between different vlans) is 
> perfectly possible on several routing platforms.

We're using Linux.  Actually, we are already routing a /32 per VLAN on the router, but up to now, we were also setting up /32 "subnets" on the downstream routers or hosts.

> http://tools.ietf.org/html/rfc3069.html

Interesting read.  It basically amounts to use /32 routes on the router, and a larger subnet (e.g. /24) on hosts, as Philip suggests.

This is a bit of a hack when hosts want to talk to each other, but this is mostly ok for the probe (or we can use proxy ARP on the router if it becomes a problem).

Thanks for the help,
Baptiste