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high ignored packets on ethernet interface

I have a 3640 router with one ethernet interface (NM1E2W) and one E1 serial interface. The ethernet interface is connected to a Cisco3550-EMI switch. The ethernet port is in a Vlan which there is only a few router resides. The end-users are in different Vlans. The serial interface is a 2Mb/s interface and connected to a WAN remote office.

The input errors on the ethernet interface is relatively high as seen below. With the guidance of 'output interpreter' I have tuned the Public buffer pool. However the problem still continues. The number of ignored packets increases.

Does anyone has any idea how I can solve this problem? (the IOS version is 12.2(17a))

Ethernet0/0 is up, line protocol is up

Hardware is AmdP2, address is 0004.ddbb.96c1 (bia 0004.ddbb.96c1)

Internet address is xxx

MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,

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

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

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 07:44:14

Input queue: 0/150/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 39000 bits/sec, 7 packets/sec

5 minute output rate 7000 bits/sec, 5 packets/sec

743250 packets input, 143930814 bytes, 0 no buffer

Received 18529 broadcasts, 0 runts, 0 giants, 0 throttles

12058 input errors, 0 CRC, 0 frame, 0 overrun, 12058 ignored

0 input packets with dribble condition detected

775357 packets output, 92544476 bytes, 0 underruns

3 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

3 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out


Re: high ignored packets on ethernet interface

An ignore is a packet that your router does not understand , if you notice your ignores and input errors are thre same , they are also logged as input errors . If you are running an ip only feature set there is soem other protocol on that segment that your ethernet is receiving then ignoring and dropping , track this down and your ignores will cease


Re: high ignored packets on ethernet interface

I don't think that ignored packet count are due to different protocols that came to the routers interface. I have used sniffers to see if there are any non-IP protocol packets coming to the interface and there are none.

More over the official explanation of the ignored packet counts is as follows:

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.

Does anyone have any other idea.

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