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Flooding the device with messages affects the device CPU performance. You can limit the rate of messages received on the device by configuring a limit for the CPU CAR.
The CPU CAR is enabled by default.
 Note |
CPU CAR is not supported with the shutdown function |
To configure limit for the CPU CAR, perform this procedure.
| Command or Action | Purpose | |
|---|---|---|
|
Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
|
Step 2 |
configure terminal Example: |
Enters global configuration mode. |
|
Step 3 |
[no] cpu-car rate Example: |
(Optional) Allows packets within the specified CPU-car rate. Use the no cpu-car command to restore the default value of 400pps. |
The commands in the following table can be used to monitor CPU performance
|
Command |
Purpose |
|---|---|
|
show cpu-car |
Displays CPU-car performance. |
|
show cpu-statistics [ethernet port-number] |
Displays CPU receiving packet port statistics. Use the clear cpu-statistics command to clear the port statistics. |
|
show cpu-classification [interface ethernetport-number] |
Displays CPU receiving packet classification statistics. Use the clear cpu-classification [interface ethernetport-number] to clear the packet classification statistics. |
|
show cpu-utilization |
Displays CPU utilization. |
The following example shows how to configure the CPU CAR speed to 50pps.
Device> enable
Device# configure terminal
Device(config)# cpu-car 50
Device(config)# show cpu-car
Send packet to cpu rate = 50 pps. Ixia A sends icmp request messages to the DUT: at a rate of 100 pps for 10 seconds, the total number of messages on the dut is 600, indicating that the cpu-car function takes effect.
Device> enable
Device# configure terminal
Device(config)# clear cpu-statistics
Device(config)# clear cpu-classification
Device(config)# clear interface
Device(config)# show cpu-statistics ethernet 1/2
Show packets sent to cpu statistic information
port 64Byte 128Byte 256Byte 512Byte 1024Byte 2048Byte
e1/2 600 0 0 0 0 0
Device(config)# show cpu-classification
Type Count Percent(%)
Total 600 100
BPDU 0 0
ERRP 0 0
ARP 0 0
MLD 0 0
IGMP 0 0
ICMP 600 100
OSPF 0 0
RIP 0 0
DHCP 0 0
SNMP 0 0
Telnet 0 0
PIM 0 0
BGP 0 0
SSH 0 0
Other 0 0
Device(config)# show statistics interface ethernet 1/2
Port number : e1/2
last 5 minutes input rate 5248 bits/sec, 10 packets/sec
last 5 minutes output rate 433832 bits/sec, 771 packets/sec
64 byte packets:1048
65-127 byte packets:0
128-255 byte packets:0
256-511 byte packets:0
512-1023 byte packets:0
1024-1518 byte packets:0
1048 packets input, 67072 bytes , 0 discarded packets
1048 unicasts, 0 multicasts, 0 broadcasts
0 input errors, 0 FCS error, 0 symbol error, 0 false carrier
0 runts, 0 giants
19 packets output, 1216 bytes, 0 discarded packets
0 unicasts, 9 multicasts, 10 broadcasts
0 output errors, 0 deferred, 0 collisions
0 late collisions
Total entries: 1.
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