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