[c-nsp] tcp 179 traffic causing high cpu on 3750/3560

[Anton Kapela]

>    It turned out that all the packets I could capture this 
> way during the high CPU period, had all in common TCP source 
> or destination port 179 (bgp).

Check out:

http://www.cisco.com/cgi-bin/Support/Bugtool/onebug.pl?bugid=CSCec51966

>   I guess this can be exploited to keep the CPU usage high on 
> 3750s, by just passing this kind of traffic through. However 
> it seems that there is a limit on CPU interrupt usage since I 
> haven't seen this going over 80% so far.

Indeed it can!

The notes from the prior CSC were:

"TCP traffic to port 179 (BGP) that is being switched through a Cisco
3550
series system is process switched.

This could lead to DoS symptoms (High CPU, malloc failures etc.) on a
Cisco
3550 system."

Getting editorial for a moment, I must air my amazement that this bug
apparently appeared again, in another platform. What the f is going on
with default tcam programming?

-Tk