It's Ars Tech's turn to bang the IPv4 exhaustion drum

Kevin Loch kloch at
Tue Aug 19 15:29:12 CDT 2008

Randy Bush wrote:
>> In practice, many routers require the packet to go twice in the hardware if
>> the prefix length is > 64 bits, so even though it is a total waste of space,
>> it is not stupid to use /64 for point-to-point links and even for loopbacks!
> some of us remember when we thought similarly for /24s for p2p links,
> especially when using rip.
> and consider matsuzaki-san's dos vulnerability on a /64 p2p link.  the
> prudent operational advice today is to use a /127.

I thought there was an issue with duplicate address detection with /127
(RFC3627)?  /126 should work and lots of folks use /112 which is a more
human-friendly bit boundary.  /112 is also good for multiple access
vlans and just about anything that isn't using autoconfig.

- Kevin

More information about the NANOG mailing list