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high ignored count and high cpu utilization on 7401 PE router

pppyyyppp
Level 1
Level 1

R1#show int gig0/1

GigabitEthernet0/1 is up, line protocol is up

Hardware is i82543 (Livengood), address is 0008.e2f8.ac06 (bia 0008.e2f8.ac06)

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation 802.1Q Virtual LAN, Vlan ID 1., loopback not set

Keepalive set (10 sec)

Full-duplex, 1000Mb/s, link type is autonegotiation, media type is SX

output flow-control is XON, input flow-control is XON

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 00:30:44

Input queue: 0/75/3024334/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 3095000 bits/sec, 1273 packets/sec

5 minute output rate 4091000 bits/sec, 949 packets/sec

3255495 packets input, 727349130 bytes, 0 no buffer

Received 115669 broadcasts, 0 runts, 0 giants, 2 throttles

3024215 input errors, 800 CRC, 16 frame, 0 overrun, 3023399 ignored <----------

0 watchdog, 764539 multicast, 0 pause input

0 input packets with dribble condition detected

2703073 packets output, 1235096281 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 pause output

0 output buffer failures, 0 output buffers swapped out

A few second later,

R1#show int gig0/1

GigabitEthernet0/1 is up, line protocol is up

Hardware is i82543 (Livengood), address is 0008.e2f8.ac06 (bia 0008.e2f8.ac06)

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation 802.1Q Virtual LAN, Vlan ID 1., loopback not set

Keepalive set (10 sec)

Full-duplex, 1000Mb/s, link type is autonegotiation, media type is SX

output flow-control is XON, input flow-control is XON

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 00:33:20

Input queue: 0/75/4022935/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 2875000 bits/sec, 1406 packets/sec

5 minute output rate 4134000 bits/sec, 1137 packets/sec

3512480 packets input, 779541769 bytes, 0 no buffer

Received 125967 broadcasts, 0 runts, 0 giants, 2 throttles

4022816 input errors, 1055 CRC, 21 frame, 0 overrun, 4021740 ignored <----------

0 watchdog, 997384 multicast, 0 pause input

0 input packets with dribble condition detected

2929340 packets output, 1321198621 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 pause output

0 output buffer failures, 0 output buffers swapped out

From: http://www.cisco.com/univercd/cc/td/doc/cisintwk/itg_v1/tr1904.htm

ignored : Shows the number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different from the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be increased.

However, when we show proc cpu, the value for 5 seconds is 98%/93%. The interrupt utilization is high at 93% and the process utilization is 98-93=5%. In this case, can we saftely say that there are too much traffic hitting the router's gig0/1 and thus cause high interrupt utilization. Is there anything else we can do?

1 Reply 1

umedryk
Level 5
Level 5

Check which process is loading the CPU. Unusual activity related to a process results in an error message in the log. Therefore, the output of the show logging exec command should be checked first for any errors related to the process which consumes lots of CPU cycles

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a00800a70f2.shtml

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