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

[Adam Vitkovsky]

Well I guess you'd like to ask what actually does rather than what might
exit the interface towards the ISP to whom you are pointing the default
route to. 
As the list of all allocated prefixes minus the list of prefixes you accept
from the other ISPs will only get you all the possibilities rather than
actual destinations used by your customers. 
So I guess the only way to really find out what destinations are covered by
the default route is enabling netflow/sflow on the particular interface and
analyze the captures. 

adam
-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
Jeffrey G. Fitzwater
Sent: Tuesday, July 02, 2013 11:01 PM
To: Saku Ytti
Cc: <cisco-nsp at puck.nether.net>
Subject: Re: [c-nsp] How to tell what routes are not in CEF and follow
DEFAULT path?

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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