[nsp] using /31s

[Sam Munzani]

Unless you care about ICMP pinging your WAN interfaces, "ip unnumbered"
works fine when conservation of ip address is desired. To monitor the
interface, make snmp query to loopback interface(If any) with IfIndex of WAN
interface. Only the catch here is populating your SNMP app with IfIndex to
monitor OR query all interface with an snmpwalk and then set filters to
ignore status of other interface you don't care about.

Sam


> Mike Sawicki wrote:
>
> >Jeff is right.  The only time I ever use /31's is to reference ip pairs
> >in filtering/acl applications.  This is really the only realm in
> >which they are valid.  Try 'ip unnumbered' if you are getting
> >desperate for space.
> >
> >
> The problem w/
>
> 'ip unnumbered'
>
> Is that you now depend on another interface being up.  Granted the other
> interface is usually a ethernet interface which is pretty reliable, you
> open yourself up to one more point of failure.
>
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