[c-nsp] 2610 High CPU Load

[Rodney Dunn]

It's interrupt probably due to the packet switching.

The numbers referenced are almost always FE2FE no features for
raw NDR (no drop rate) test.

For serial it's going to be less. Add features and it's less also.

Rodney

On Fri, Nov 14, 2008 at 11:19:38AM +0200, Gideon le Grange wrote:
> Good day
> 
> I have a CPU load problem on a 2610. The router has a X21 Serial  
> interface and Ethernet, and does simple WAN routing. As the amount of  
> traffic increases, the CPU load increases as well, and when the  
> throughput is around 1.2Mbit at  about 2000 packet/s, the CPU is  
> running so high that the box becomes unresponsive. This router is  
> theory supposed to be capable of doing 7.68Mbps at 15,000 pps.
> 
> I've checked that the router isn't doing processor switching, and as  
> far as I can see the vast majority of the traffic is being fast  
> switched, yet I seem to be hitting the documented performance limits  
> for process switching.
> 
> If I have to replace the router I can, but would like to know why I'm  
> running into trouble when the current router is supposedly well within  
> it's limits.
> 
> The box is running 12.3(9), but I've had the same issue on a 12.1  
> version. Below is the output of 'show interfaces stat' and 'show  
> interface switching' .
> 
> Any ideas/help is appreciated.
> 
> ---
> 
> 
> 
> # sh int stat
> 
> 
> Ethernet0/0
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                Processor         97      10200        219      17650
>              Route cache     760678   57144419     626362   47003211
>                    Total     760775   57154619     626581   47020861
> Serial0/0
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                Processor        467      37390        337      43569
>              Route cache     626497   40745693     760817   49520393
>                    Total     626964   40783083     761154   49563962
> 
> -----
> 
> #sh int switching
> 
> 
> Ethernet0/0
>           Throttle count          0
>                    Drops         RP          0         SP          0
>              SPD Flushes       Fast          0        SSE          0
>              SPD Aggress       Fast          0
>             SPD Priority     Inputs       3524      Drops          0
> 
>     Protocol  IP
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                  Process       3577     283416       3699     340458
>             Cache misses         96          -          -          -
>                     Fast   20283972 1524355199   16554208 1236628784
>                Auton/SSE          0          0          0          0
> 
>     Protocol  ARP
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                  Process         44       2640       4328     259680
>             Cache misses          0          -          -          -
>                     Fast          0          0          0          0
>                Auton/SSE          0          0          0          0
> 
>     Protocol  CDP
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                  Process        435     178350        435     133110
>             Cache misses          0          -          -          -
>                     Fast          0          0          0          0
>                Auton/SSE          0          0          0          0
> 
>     Protocol  Other
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                  Process        869      46926       2601     156060
>             Cache misses          0          -          -          -
>                     Fast          0          0          0          0
>                Auton/SSE          0          0          0          0
> 
>     NOTE: all counts are cumulative and reset only after a reload.
> Serial0/0
>           Throttle count          0
>                    Drops         RP          0         SP          0
>              SPD Flushes       Fast          0        SSE          0
>              SPD Aggress       Fast          0
>             SPD Priority     Inputs       5209      Drops          0
> 
>     Protocol  IP
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                  Process      17620    1589429      13114    1548222
>             Cache misses      14327          -          -          -
>                     Fast   16555485 1071171389   20287359 1321039479
>                Auton/SSE          0          0          0          0
> 
>     Protocol  CDP
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                  Process        429     137280        437     122797
>             Cache misses          0          -          -          -
>                     Fast          0          0          0          0
>                Auton/SSE          0          0          0          0
> 
>     Protocol  Other
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>                  Process          1         14        238       3784
>             Cache misses          0          -          -          -
>                     Fast       2750      44000          0          0
>                Auton/SSE          0          0          0          0
> 
>     NOTE: all counts are cumulative and reset only after a reload.
> 
> 
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