Administrator Guide

Layer 2 Switching Commands 400
This command does not affect the rate limits for control plane packets. It is
almost never necessary to use this command to change from the default
value. The use of this command should be restricted to situations in which
moderate to high rates of unknown unicast/multicast are continually sent to
the switch CPU as evidenced by the show process cpu command and where
the ipMapForwardingTask is showing high CPU usage. This occurs most
frequently in networks where a high number of ARPs are continually received
on untrusted ports, high numbers of L2 stations are timing out and
reappearing or multicast flooding is occurring in the network. If problems
with L2, L3 or multicast learning occur after changing this value, set the rate
limit back to the default value and take other steps to correct or mitigate the
underlying network issue directly.
Use the show system internal pktmgr command to show the configured
value.
Example
The following example shows output with higher than normal CPU usage due
to packets copied to the software forwarding task.
console#show process cpu
Memory Utilization Report
status bytes
------ ----------
free 1053933568
alloc 673873920
CPU Utilization:
PID Name 5 Secs 60 Secs 300 Secs
---------- ------------------- -------- -------- --------
1129 osapiTimer 0.00% 0.00% 0.01%
1133 _interrupt_thread 0.09% 0.01% 0.00%
1137 bcmCNTR.0 0.24% 0.31% 0.31%
1142 bcmRX 23.00% 27.01% 18.01%
1147 ipMapForwardingTas 32.97% 37.11% 29.92%
1155 bcmLINK.0 0.34% 0.36% 0.36%
1156 cpuUtilMonitorTask 0.09% 0.05% 0.04%
1170 nim_t 0.09% 0.08% 0.07%
1208 dot1s_timer_task 0.00% 0.00% 0.01%
1222 snoopTask 0.00% 0.00% 0.01%
1291 RMONTask 0.00% 0.02% 0.03%