[c-nsp] 2610 High CPU Load

[Gideon le Grange]

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.