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Catalyst Underruns/Output Buffer Failures

I can't find any information (bug Navigator, technical tips, CCO documentation, etc.) which I understand about Underruns in the output of the command

"show interface FastEthenet 0/X" for a Catalyst 3500XL.

I have the next output in some of my ports:

HQ-SW#show interface

FastEthernet0/47 is up, line protocol is up

Hardware is Fast Ethernet, address is 0002.b9cd.822f (bia 0002.b9cd.822f)

MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

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

Encapsulation ARPA, loopback not set

Keepalive not set

Auto-duplex (Full), Auto Speed (100), 100BaseTX/FX

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

Last input never, output 00:00:01, output hang never

Last clearing of "show interface" counters 1d00h

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 4000 bits/sec, 4 packets/sec

154735 packets input, 29142807 bytes

Received 284 broadcasts, 0 runts, 0 giants, 0 throttles

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

0 watchdog, 0 multicast

0 input packets with dribble condition detected

245598 packets output, 23693638 bytes, 1019 underruns

0 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

1019 output buffer failures, 0 output buffers swapped out

I can't understand why I'm having Underruns and for this I assume are the output buffer failures.

Does Underruns meant those frames that the switch port can't handle because it hasn't buffers?

what are causing in this case overruns?, there isn't any excesive utilization with this switch port, very low indeed, or any speed mismatch, and you can see only 280 broadcasts.


Re: Catalyst Underruns/Output Buffer Failures

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