High IP Input CPU load on Cisco 881

[leksanderz]

Good day everyone.

I have the problem with high CPU consumption by IP Input process. I have tried to beat this by myself according to troubleshooting high CPU load guide and troubleshooting high CPU load caused by IP Input process guide as well, but unfortunately with no success.

I have a Cisco 881 router (config without sensitive data and unrelated stuff is attached, also I've removed 94 ip dhcp pool entries, used for static DHCP assigning) and two SF-300/48 switches, each of them connected to router via interfaces FA0/0 and FA0/1 respectively. Interface FA0/4 is a WAN interface with 100 Mb/s link to the ISP.

I have tried connecting to the router only via my test notebook. Still, the maximum speed I've got is ~25 Mb/s download and ~65Mb/s upload. At the time of speed testing sh proc cpu command indicates 99%/34% CPU load. At normal (without any significant traffic load) CPU load rests at 16%/5%. I've attached sh proc cpu sorted command listing at the time of speed testing, too.

I am asking for your advice, and waiting for any assistance.

[Mark Malone · Accepted solution]

hi theres a huge amount of interrupt traffic at cpu level there , 34% , thats processed switched traffic hitting the cpu causing spike, cef is in place, how hot are your interfaces running as there fast ethernet ? looks like router could be overloading

You will never get a 100mb out of an 881 anyway ,25mb is about right for those routers , even the spec sheet states that but they can vary a bit depending whats configured , ipsec can half the throughput , NAT uses up resources too, i have seen them only getting 15mb with that enabled

https://supportforums.cisco.com/sites/default/files/attachments/discussion/white_paper_c11_595485_19.pdf

http://www.cisco.com/c/en/us/support/docs/routers/7500-series-routers/41160-highcpu-ip-input.html

[leksanderz]

Thank you for information provided, it seems now that problem is absent.