Show int "Last input never" but counts are g.t. zero?

Answered Question
Nov 12th, 2009
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I am trying to decide how recently an interface has been used, if at all. "Show int" says, "Last input never, output 1w 3d", but the input counts are all greater than zero. The link of course is down. How does this happen? Or am I misinterpreting what "Last input never, output never" means?



> show int fa0/5

FastEthernet0/5 is down, line protocol is down

Hardware is Fast Ethernet, address is 0004.27cd.4345 (bia 0004.27cd.4345)

MTU 1500 bytes, BW 0 Kbit, DLY 0 usec,

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

Encapsulation ARPA, loopback not set

Keepalive not set

Auto-duplex , Auto Speed , 100BaseTX/FX

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

Last input never, output 1w3d, output hang never

Last clearing of "show interface" counters never

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 0 bits/sec, 0 packets/sec

693231 packets input, 65801676 bytes

Received 5831 broadcasts, 0 runts, 0 giants, 0 throttles

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

0 watchdog, 5056 multicast

0 input packets with dribble condition detected

928808 packets output, 552742079 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out


Correct Answer by arjmenon about 7 years 7 months ago

http://www.cisco.com/en/US/docs/ios/interface/command/reference/ir_s4.html#wp1014358


Last input


Number of hours, minutes, and seconds since the last packet was

successfully received by the interface and processed locally on the

router. This field is useful for detecting when a dead interface failed.


Note This field is not updated by fast-switched traffic.


on the c4500 we have the "sh interfaces link in CLI"...

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Giuseppe Larosa Thu, 11/12/2009 - 23:57
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Hello Wiley,

on some switches I could see last input never for live ports with traffic over it!


this should be what Cisco would call a cosmetic bug.


Hope to help

Giuseppe


iyde Fri, 11/13/2009 - 09:18
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Hi.


Quite right! In some Catalyst switches (I believe Cat3550 and older) this bug is present. You can have an interface which is up/up and a lot of traffic running across but it still says "Last input never".

This cosmetic bug never got fixed - I expect that it is a hardware limitation.


HTH, Ingolf

Correct Answer
arjmenon Fri, 11/13/2009 - 23:57
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http://www.cisco.com/en/US/docs/ios/interface/command/reference/ir_s4.html#wp1014358


Last input


Number of hours, minutes, and seconds since the last packet was

successfully received by the interface and processed locally on the

router. This field is useful for detecting when a dead interface failed.


Note This field is not updated by fast-switched traffic.


on the c4500 we have the "sh interfaces link in CLI"...

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