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Beginner

Strange ip cef behavior on Cisco 2951

Hello.

I have 2 Cisco 2951 configured with HSRP. Everything woks fine, but after few hours ip cef stop working. If I try to disable ip cef (no ip cef) and enable again (ip cef), it wont start. If I reboot the router ip cef work again as expected. I have 300 users on this router.

 

My software version flash0:c2951-universalk9-mz.SPA.150-1.M6.bin.

 

Any sugestion would be helpfull

Everyone's tags (1)
11 REPLIES 11
VIP Advisor

Re: Strange ip cef behavior on Cisco 2951

Look at some bugs reported :

 

https://www.cisco.com/c/en/us/td/docs/ios/15_0/release/notes/150MCAVS.html

 

if possible upgrade and check.

BB
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VIP Mentor

Re: Strange ip cef behavior on Cisco 2951

Hello,

 

sounds like a bug...can you upgrade to release 15.7.3M3 MD ? Your 15.0.1 release is fairly outdated (2012)...
 

Beginner

Re: Strange ip cef behavior on Cisco 2951

Guys, thank you for your fast response. Bug was my first thought...... Unfortunately we don not have contract with Cisco , because we buy this device as refurbished.......

I have c2900-universalk9-mz.SPA.155-3.M5.bin, but i receive message that this software is not OK, for this device.

 

So....I can't do nothing :-(

Rising star

Re: Strange ip cef behavior on Cisco 2951

How did you decide that it's cef?
Beginner

Re: Strange ip cef behavior on Cisco 2951

I replace routers Cisco 2850 with 2951 and made redesign. I monitored old routers and I saw that CPU utilization was around 40 - 50%. When I replace routers with 2951 I saw that CPU utilization on new routers was + 90% and find that SNMP process was troublemaker. I shut down SNMP, and everything was OK - CPU between 20 - 30 %. after 5 hours CPU rise to 80% and regarding to the high traffic utilization rise and rise.

After deep research I find that ip cef is disabled - strange because I didn't change this in configuration. Like already said I try enable ip cef again but nothing happened. When I reboot the router and write command show ip cef I see that ip cef works fine and it is enabled. When ip cef work as should work than CPU utilization is around 20%.

My thought was also that something is wrong with router and I switched (HSRP) from Primary router to Secondary (where I saw that ip CEF  was OK). It works 8 hours and than ip cef stop working too (show ip cef return that ip cef is disabled). On both routers is the same software.

So I decide that something is wrong with ip cef.....

 

VIP Advisor

Re: Strange ip cef behavior on Cisco 2951

That good diag step you followed.

 

I am not sure, i were you, since you do not have Cisco contact to upgrade IOS,

 

use EEM Script to run, if ip cef disabled enabled back ( enable some logs see why this was going to disable)

 

Still think how come ip cef disables  automatically ?

 

some post for reference, again they have recommended to contact TAC

 

https://community.cisco.com/t5/routing/cef-not-running-even-though-enabled-globally/td-p/2882256

 

 

 

BB
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Rising star

Re: Strange ip cef behavior on Cisco 2951

Maybe somthing wrong with the configuration...
Could you share it?
Beginner

Re: Strange ip cef behavior on Cisco 2951

.....maybe I am a litle bit lucky :-) . I find router with  software c2951-universalk9-mz.SPA.157-3.M3. So , I upload this software to my Primary gateway and , I will wait, to see what will be in next hours. Now I run on version 15.7-3M3.

 

Guys, you are awesome with your support. I will report how this case will finish.

VIP Advisor

Re: Strange ip cef behavior on Cisco 2951

Seems to be Luck Favoring you now this year.. keep post us what you find for us and community.

 

BB
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Beginner

Re: Strange ip cef behavior on Cisco 2951

I would like to inform you, that after software upgrade everything works fine ;-)

 

Thank you all for your help.

Regards

Highlighted
VIP Advisor

Re: Strange ip cef behavior on Cisco 2951

Good to know, if the thread is helpfull and solve, mark as solve, so it will be helpfull for other community members, if they have similar issue.

 

BB
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