[c-nsp] /31 network

[Kevin Graham]

> has anyone used /31 network instead of /30? I believe this is recommended to
> use /31 network? Need expert comments.

Support still seems very limited, but on a similar thread, has anyone toyed
with the 'ip unnumbered for Ethernet' feature? Initially it was just option-82
magic, but I noticed there's now also a "poll" option to support non-DHCP
hosts:

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/37sg/configuration/guides/unnumber.html

There's the single message from a CLI example:

     "Warning: dynamic routing protocols will not work on non-point-to-point
     interfaces with IP unnumbered configured."

...though without more discussion on the underlying functionality, that's
terribly vague (ie. would explicit neighbor configurations remedy the
limitiation?).