It won't achieve anything. Infact, matching against a
null0 interface isn't going to gain you anything since
it will always match. So, you might as well just match
on other criteria and leave the 'match interface
null0' out of your route-map statement.
Maybe the person who did the config your trying to
figure out didn't understand route maps or something
and plugged in commands until it worked....
As far as which interfaces it will match, since null0
is up all the time - it will match on the criteria in
the ACL if you have 'match ip address' and set the
criteria defined if any. I can't think of a reason to
use null0 for match interface offhand because it's
basically the same as not having a 'match interface'
in the config.
Now, a 'set interface null0' makes sense. That would
take the traffic that matched the ACL and route it to
the null0 interface which would blackhole/kill that
traffic basically.
--- Stephen Skinner <[EMAIL PROTECTED]> wrote:
> Hi ,
> Can i ask ??
>
> but i thought that the null0 int was always up (i.e
> loopback fashion)
> so what is the point of putting the second null0
> statement???
>
> Confused...(but thick enough to be happy)
>
> steve
>
> >From: "Erick B." <[EMAIL PROTECTED]>
> >Reply-To: "Erick B." <[EMAIL PROTECTED]>
> >To: Jon Kuhn <[EMAIL PROTECTED]>,
> "'[EMAIL PROTECTED]'"
> ><[EMAIL PROTECTED]>
> >Subject: Re: OSPF config
> >Date: Tue, 20 Feb 2001 15:43:14 -0800 (PST)
> >
> >I would say it will always go through, since null0
> is
> >always up. The route-map will perform the actions
> >specified if the match conditions are all true. The
> >second null0 is a second interface to match against
> if
> >first one is down/unavailabe.
> >
> >if you had:
> >
> >route-map test perm 10
> > match interface s0 s1
> > set ip next-hop x.x.x.x
> >
> >if s0 is down, but s1 is up then the next-hop will
> be
> >changed. If s1 was also down then nothing would be
> >changed and normal routing would occur.
> >
> >
> >--- Jon Kuhn <[EMAIL PROTECTED]> wrote:
> > > Hi all,
> > >
> > > There's a route map for an OSPF configuration
> I'm
> > > working on that has a
> > > line:
> > >
> > > match interface Null0 Null0
> > >
> > > Does this mean match any interface or no
> interface?
> > > I can't get any
> > > information from cisco.
> > >
> > > Thanks!
> > > Jon
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