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[show interfaces] output errors


when looking at a gigabitethernet interface i found that it's experimenting output errors. i was wondering exactly what could cause this and how to fix it. as far as i know having output errors on a GE is not posible wihout having underruns. anybody can explain to me what an output error means?

show interfaces gigabiteternet4/16

GigabitEthernet4/16 is up, line protocol is up

Hardware is Gigabit Ethernet Port, address is 0009.e844.8def (bia 0009.e844.8def)

Description: Puerto Reservado para red - Servidores

MTU 1500 bytes, BW 100000 Kbit, DLY 10 usec,

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

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s

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

Last input never, output never, output hang never

Last clearing of "show interface" counters 1w0d

Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

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

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

944321295 packets input, 2720591607 bytes, 0 no buffer

Received 70828 broadcasts, 0 runts, 0 giants, 0 throttles

3973 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 input packets with dribble condition detected

405055722 packets output, 2638160929 bytes, 0 underruns

277529 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out




Re: [show interfaces] output errors

definition from cco

Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams might have more than one error, and others might have errors that do not fall into any of the specifically tabulated categories.

I would look at a burst of traffic hitting the interface and filling the Rx ring hence causing drops. The burst of traffic is too much for the interfasce to handle so it drops the packets .


Re: [show interfaces] output errors

fyi: if the product is a cat6500 or cat4500 use the "show int gig4/16 counters errors" command instead. Gives a more readable breakdown of errors on a interface.


Re: [show interfaces] output errors

I have found the doc I was looking for on CCO

this states

Number of times that the receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.

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