1841 at 99% CPU what can I do?

[Andy White]

Hello,

I've never had a router's CPU suddenly hit 99% and just stay like it for hours even after a reboot.  This router really does nothing with regards to CPU, I'm looking at it's CPU history (via SolarWinds Orion NPM software that we use) and it is arounf 1-3% all the time for the past 2 years.

What commands can I use to diagnose the issue?

I did a show debugigng and it seems no debugging is running

Thanks

[Sandeep Choudhary]

Can you paste the output of this command;:

show processes cpu

see this link:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_tech_note09186a00800a65d0.shtml?referring_site=bodynav

Regards

Please rate if it helps.

[Peter Paluch]

Hi Andy,

Can you see the output of the show process cpu sorted 1m and post it here? This output should tell you the processes whose 1-minute CPU load average is the highest. This should eventually help us see what process consumes the most of your CPU power.

Best regards,

Peter

[Andy White]

Thanks guys, it's

97.37%    IP NAT Ager

The routers main purpose is to NAT to be honest.

[Sandeep Choudhary]

Hi Andy,

To find out the root cause you can enable netflow in your local lan  interface and find out whats happening with the traffic transactions.

With that you can come to a solid conclusion or atleast get a clue on what is making or hogging the CPU up.

Configure ip route-cache flow under your local lan ethernet interface and make use of show ip cache flow to check the traffic transactions.

Hope the below link helps u out.

http://www.cisco.com/en/US/docs/ios/12_3/switch/command/reference/swi_s1.html#wp1066187

may be its a Buggy IOS, upgrade.?

regds

Please rate if it helps.

[Andy White]

Maybe a bug, Neflow is already running and shows hardly any traffic.

[Andy White]

Memory is up from 20% to 80% too.

[Harish Balakrishnan]

Hello Andy

Can you give a     clear ip nat translation *     and see whether the CPU comes down.. and what is the traffic on the outgoin interface show interface < interface name>

Regards

Harish.

[Andy White]

Hi, I've already clear the table and it still stays at 99%

IOS is old, had a look a newer IOS but there are so many to choose, I'd appreciate if you can help locate a newer one?  Form the below output it would seem that the memory is 128mb and flash 32mb, I tried to see if this current IOS has been deferred but it wasn't listed.

Compiled Fri 30-Nov-07 14:10 by prod_rel_team

ROM: System Bootstrap, Version 12.3(8r)T8, RELEASE SOFTWARE (fc1)

NAT_router uptime is 3 hours, 23 minutes

System returned to ROM by power-on

System restarted at 11:14:50 bst Mon Oct 8 2012

System image file is "flash:c1841-ipbasek9-mz.124-18.bin"

Cisco 1841 (revision 5.0) with 114688K/16384K bytes of memory.

Processor board ID FCZ092822QY

2 FastEthernet interfaces

DRAM configuration is 64 bits wide with parity disabled.

191K bytes of NVRAM.

31744K bytes of ATA CompactFlash (Read/Write)

[Sandeep Choudhary]

Hi Andy,

See this link:http://tools.cisco.com/ITDIT/CFN/
Chosse what services you want on router and  decide which IOS u can take.

Regards

Please rate if it helps.