Hardware CEF entry usage is at 95% capacity for IPv4 unicast protocol

If you see this log which is “Hardware CEF entry usage is at 95% capacity for IPv4 unicast protocol” in you cisco 7600 router, you need fix it as soon as possible. This log means you CEF table soon will be full.  
if the routes entry is exceed the CEF table capacity,  traffic to the exceeded route will be drop.  if this router is you internet gateway router, the symptom for you will be some websites are unreachable.

RSP720-3CXL CEF table is up to 1M of IPV4 + MPLS +IP Multicast + IPV6  routes.  The default value is below

IPv4 + MPLS         - 512k (default)
IPv6 + IP Multicast - 256k (default)

Use the below command to see your router current CEF maximum entry

show mls cef maximum-routes

The output is below

Current :

-------

 IPv4 + MPLS         - 512k (default)
 IPv6 + IP Multicast - 256k (default)

Use "show mls cef su" to see how many actual routes currently is

The output is below
Total routes:                     519884
    IPv4 unicast routes:          495601
    IPv4 Multicast routes:        3    
    MPLS routes:                  6602 
    IPv6 unicast routes:          17678
    IPv6 multicast routes:        3    
    EoM routes:                   0

The below command is how to adjust the CEF table

(config)#mls cef maximum-routes ?
  ip            number of ip routes
  ip-multicast  number of multicast routes
  ipv6          number of ipv6 routes
  mpls          number of MPLS labels

for example, change the CEF for ipv4 to 768K

(config)# mls cef maximum-routes ip 768

You need save it and reload router.

Use the “show mls cef maximum-routes” to verify the change before reload.  The output for "show mls cef maximum-routes" before reload is like below

Current :-
-------
 IPv4 + MPLS         - 512k (default)
 IPv6 + IP Multicast - 256k (default)
User configured :-
---------------
 IPv4                - 768k 
 MPLS                - 16k (default)
 IPv6 + IP Multicast - 120k (default)
Upon reboot :-
-----------
 IPv4                - 768k 
 MPLS                - 16k (default)
 IPv6 + IP Multicast - 120k (default)

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