nanog mailing list archives
Re: Using /31 for router links
From: Nathan Ward <nanog () daork net>
Date: Sat, 23 Jan 2010 17:11:12 +1300
On 23/01/2010, at 1:31 PM, Jay Nugent wrote:
Greetings, On Fri, 22 Jan 2010, Seth Mattinen wrote:In the past I've always used /30's for PTP connection subnets out of old habit (i.e. Ethernet that won't take unnumbered) but now I'm considering switching to /31's in order to stretch my IPv4 space further. Has anyone else does this? Good? Bad? Based on the bit of testing I've done this shouldn't be a problem since it's only between routers.Yes, this *IS* done *ALL* the time. P-t-P means that there are ONLY two devices on the wire - hence point to point. It ONLY uses two IP addresses (one on each end) and there is no reason or need to ARP on this wire. So no need for a broadcast or network addresses - it is just the two end points.
ARP is still required on ethernet links, so that the MAC address can be discovered for use in the ethernet frame header. /31 does not change the behavior of ARP at all. -- Nathan Ward
Current thread:
- Using /31 for router links Seth Mattinen (Jan 22)
- Re: Using /31 for router links Jay Nugent (Jan 22)
- Re: Using /31 for router links Nathan Ward (Jan 22)
- RE: Using /31 for router links George Bonser (Jan 22)
- Re: Using /31 for router links Nathan Ward (Jan 22)
- Re: Using /31 for router links Joe Provo (Jan 22)
- Re: Using /31 for router links Seth Mattinen (Jan 22)
- Re: Using /31 for router links Chris Costa (Jan 22)
- Re: Using /31 for router links Jens Link (Jan 23)
- RE: Using /31 for router links Erik L (Jan 22)
- Re: Using /31 for router links Seth Mattinen (Jan 22)
- Re: Using /31 for router links kris foster (Jan 22)
- Re: Using /31 for router links Richard A Steenbergen (Jan 22)
- Re: Using /31 for router links Jay Nugent (Jan 22)
- Re: Using /31 for router links Tony Varriale (Jan 22)
- Re: Using /31 for router links Florian Weimer (Jan 23)