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Webcast-Catalyst9k
New Member

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

I'm using router 7609 for bgp peering and when i reload the router then i faced following error. Please help me to get rid of this error.

*Jul 12 17:09:36.862: %MLSCEF-SP-STDBY-4-FIB_EXCEPTION_THRESHOLD: Hardware CEF entry usage is at 95% capacity for IPv4 unicast protocol.

*Jul 12 17:09:39.261: %CFIB-SP-STDBY-3-CFIB_EXCEPTION: FIB TCAM exception for IPv4 unicast. Packets through some routes will be dropped.

Use "mls cef maximum-routes" to modify the FIB TCAM partition or/and consider a hardware upgred.

Examine your network and collect the necessary information from this setup.

The only way to recover from this state is by reload the  router.

9 REPLIES
Cisco Employee

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

Hi Prabin,

Check out this thread - it is relevant to your issue.

https://supportforums.cisco.com/thread/2113775

Best regards,

Peter

New Member

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

Hello Peter,

Thank you very much for your response.

I read that post and other forum too. I incresed to maximum value by entering command "

mls cef maximum-routes ip" but again faced same problem.

Is it necessary to change my sup engine 720?

New Member

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

Hi Prabin,

please share the output of:

show mls cef max

show mls cef summary

Regds,

-Ankit

Ankit Gupta Cisco Systems India
New Member

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

Dear Ankit,

mls cef maximum-routes ip 239K

Router#sh mls cef maximum-routes

FIB TCAM maximum routes :

=======================

Current :-

-------

IPv4                - 222k

MPLS                - 2k (default)

IPv6 + IP Multicast - 16k (default)

Router#sh mls cef summ

Total routes:                     229033

    IPv4 unicast routes:          226980

    IPv4 Multicast routes:        3    

    MPLS routes:                  2048 

    IPv6 unicast routes:          2    

    IPv6 multicast routes:        3    

    EoM routes:                   0 

I read from post that if the cef value is maximum then there will be increase in CPU processing power. If that happens then  will it create a problem and how to solve this one?

With Regards

Prabin

Hall of Fame Super Gold

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

You have to choices:

receive less prefixes

or

upgrade hardware.

Nothing else.

New Member

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

Hello Prabin,

As you have reached the max limit, than you need to upgrade hardware or else try to reduce the routes. In case of SUP720, i dont think that this will have any impact on the CPU.

Regds,

Ankit Gupta

Ankit Gupta Cisco Systems India
Bronze

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

Hi Prabin,

Just curious.

Hope you are peering with Service providers for Internet. If yes, why are you receiving so many routes? You may ask
your provider to reduce or filter at your level as the second option. Pls question whether you need ALL those detailed routes in the first place.

Ashok.

Sent from Cisco Technical Support iPhone App

With best regards... Ashok ----------- Pls kindly rate if helpful or answered your question.
New Member

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

Dear Ashok,

We are peering with 2 ISP and with National Internet Exchange (NIX) also.

I'm not so much expert in BGP so just want to know if we reduce or filter routes then will that create problem?

With Regards,

Prabin

Bronze

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

Hi Prabin,

Ok. I would suggest you to please go through the following link...

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c95bb.shtml

You need to do BGP Fine tuning and interact with your providers to apply proper filters wherever possible depends upon what you require instead of accepting FULL routes from all the providers add up to 211K+.

Replacing the hardware is not a good option than re-designing your network to customize to your needs.

With best regards...
Ashok
-----------
Pls kindly rate if helpful or answered your question.

With best regards... Ashok ----------- Pls kindly rate if helpful or answered your question.
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