High CPU Utilization - TTY Background

[buchynska]

Hello. I have Cisco 2610, and its CPU utilization grows from 3% to 70% in 5 days, and i have to reload it every 4-5 days.

The process, which loads CPU most of all is TTY Background.

Command "logging synchronous" is not present, ip accounting, debugging is also turned off, and the traffic is actually very poor, errors - too, log is almost empty.

Do you have any ideas?

Regards, Galyna.

[n.bowbridge]

Which IOS version are you using?

[buchynska]

c2600-i-mz.123-1a.bin

[Bobby Thekkekandam]

I've seen cases where a modem connected to the aux port caused high cpu in TTY Background. Do you happen to have anything connected to the aux port?

-Bobby

[buchynska]

No, there is nothing on aux port.

[buchynska]

I have just noticed that CPU load suddently fell down from 50% to 8%.

All that happened on that time was i typed no shutdown on one of the Async interfaces, and after an hour - shutdown again, but didn't reload.

I'll see if it will grow the same way or not.

Anyway i don't like its unpredictable behavior.

[Bobby Thekkekandam]

That kind of makes sense, as the TTY background process is a generic process used by all terminal lines (console, aux, async, and so on.

Now, although you've checked for the classic signs of CSCdy01705, the version of IOS that you are running does not have the fix -- 12.3(2) was the first 12.3 mainline release with the fix. Also, there are numerous bugs with varying symptoms that were duplicated to the same bug, so you could still be running into that.

HTH,

Bobby