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

[Saku Ytti]

On (2013-07-02 21:00 +0000), Jeffrey G. Fitzwater 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.

You'd need to analyse your copy of FIB offline, it wouldn't be too hard,
but I'm dubious of its benefits.


Maybe more useful would be to see what traffic actually hits it, you could
do this via evil hack.

Loop two cables together:

Int gigaloop1
  ip address 10.10.10.0 255.255.255.254
int gigaloop2
  ip vrf forwarding HACK
  ip address 10.10.10.1 255.255.255.254
int Internets
  ip address 192.0.2.1 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 gigaloop1 10.10.10.1
ip route vrf HACK 0.0.0.0 0.0.0.0 Internets 192.0.2.2
!
monitor session 1 source interface gigaloop1
monitor session 1 destination interface gigaspan


Now you'd have port-monitor for traffic hitting default route :)


(Extra points for doing this by poking in TCAM new LTL index for the 0.0.0.0
adjacency index)

-- 
  ++ytti