[c-nsp] How to tell what routes are not in CEF and follow DEFAULT path?

[Clint Wade]

The only way I am aware of would be to do a "show ip cef <Intf>" on the
interfaces facing your ISP. Although if you're carrying a full BGP table
that's most likely all you would see. The only other way I am aware of via
the cef table is to do a "show ip cef <10.10.10.1> where the 1 is a valid
host in that internal network, CEF will output the entry for the interface
that subnet is routed to.


All of these require legwork and are not completely automated. Any routes
that CEF kicks back as not having an internal route are going to show a
next-hop via 0.0.0.0/0


On Tue, Jul 2, 2013 at 4:00 PM, Jeffrey G. Fitzwater <jfitz at princeton.edu>wrote:

> I have 0.0.0.0 pointing to one of our ISP so that any prefix < /24 ( which
> we don't permit in from any ISP) would get pushed to that ISP which might
> have route.
>
> I am just trying to figure out how may are being pushed to default.
>
>
>
> Jeff F.
> On Jul 2, 2013, at 4:53 PM, Saku Ytti <saku at ytti.fi>
>  wrote:
>
> > On (2013-07-02 20:19 +0000), Jeffrey G. Fitzwater wrote:
> >
> >> I would like to find out what routes are NOT in my route table and
> therefore follow the DEFAULT path to 0.0.0.0.
> >>
> >> Would  "show ip cef unresolved" work ?  I get nothing back when I run
> it but maybe there is nothing to see.
> >
> > What you imagine is FIB covering all possibilities and then next-hop or
> > null, it would not scale and makes no sense. 0.0.0.0 is branch when there
> > is no matching top-level branch.
> >
> > You could produce such data offline and aggregate it to maximally.
> >
> > --
> >  ++ytti
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