[c-nsp] 3640 CPU load question

[Temkin, David]

I've found tcp / rtp header compression to be absolutely killer on
3640's.  Try turning it off and see if makes a marked difference.

-Dave 

> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net 
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Burton Windle
> Sent: Tuesday, October 26, 2004 1:06 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] 3640 CPU load question
> 
> I have a 3640 with 128mb memory running 12.2(24). It has one 
> FastEth interface, and 8 serial interfaces (each with an 
> Adtran T1 CSU hanging off of them).  The network setup is 
> hub-n-spoke, with the 3640 being the center of the WAN hub.
> 
> I would think the router should be snoozing; the FastE int 
> pushes about
> 1.5 megabits/sec (700 packets/second), and the busiest T1 
> averages much less than a full T1 (200pps, 400kilobit/sec). I 
> have no real ACLs to speak of, the router doesn't do any NAT, 
> and runs EIGRP. I do MRTG polling for the interface bandwith 
> stats every 5 minutes, and the router exports NetFlow data. I 
> also have 'ip tcp header-compression' & 'ip rtp 
> header-compression' turned on for each serial interface.
> 
> However, the router sits at 25% CPU usage (CPU utilization for five
> seconds: 30%/30%; one minute:  25%; five minutes: 25%) all 
> the time. Does this CPU usage seem high?
> 
> A 'show proc cpu' doesn't show anything interesting:
> 
> 5-3640-WAN#show proc cpu | exclude 0.00
> CPU utilization for five seconds: 30%/27%; one minute: 28%; 
> five minutes: 27%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>    3        7768      1233       6300  2.03%  0.61%  0.44% 
> 130 Virtual Exec
>   21     1735868   4072677        426  0.08%  0.06%  0.03%   
> 0 Per-Second Jobs
>   31     5343616  13613338        392  0.08%  0.13%  0.14%   
> 0 IP Input
>   70     2664044  19148167        139  0.08%  0.09%  0.06%   
> 0 IP-EIGRP Hello
> 
> Here is a snippet of the config for the interfaces:
> 
> interface FastEthernet0/0
>  ip address 192.168.1.4 255.255.255.0
>  ip route-cache flow
>  speed 100
>  full-duplex
> !
> interface Serial1/0
>  bandwidth 1536
>  ip address 10.255.110.1 255.255.255.252  service-policy 
> output WAN  ip tcp header-compression iphc-format  serial 
> restart-delay 0  ip rtp header-compression iphc-format !
> 
> 
> 
> A gentle proding with a Clue-By-Four would be appreciated.
> 
> -- 
> Burton Windle                           bwindle at fint.org
> 
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