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CEF No_route

milan.kulik
Level 10
Level 10

Hi,

I can see

Router1#sh cef drop
CEF Drop Statistics
Slot  Encap_fail  Unresolved Unsupported    No_route      No_adj  ChkSum_Err
RP      11181644          30746                       0                  479299                0        3           992     

on my router with the number of   No_route increasing.

   Looking to the Command Reference, No_route " Indicates the number of packets dropped due to a missing  prefix in the FIB table." 

  What I don't understand is:

When there is a static default route present in the RIB (my case), how can any packet be dropped due to "missing prefix in the FIB"?

Thanks,

Milan

2 Replies 2

gephelps
Cisco Employee
Cisco Employee

Can the router resolve the next hop for the default route?

Yes, it can.

The only non-standard fact is it's using a recursive route lookup for the default route next-hop:

Router1#sh ip route 0.0.0.0
Routing entry for 0.0.0.0/0, supernet
Known via "static", distance 1, metric 0, candidate default path
  Redistributing via bgp 65000
Routing Descriptor Blocks:
  * 192.168.189.6
Route metric is 0, traffic share count is 1


Router1#sh ip cef 200.1.1.1
0.0.0.0/0, version 20760790, epoch 0, per-destination sharing
0 packets, 0 bytes
Flow: Origin AS 0, Peer AS 0, mask 0
  via 192.168.189.6, 0 dependencies, recursive
    next hop 192.168.167.3, FastEthernet0/0 via 192.168.189.0/24
valid adjacency
  Recursive load sharing using 192.168.189.0/24.

BR,

Milan

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