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Viewing inactive ports on a Cisco 2960 switch

IgorHamzic
Level 1
Level 1

Hi.Is there a way to view which ports have been inactive for a long time on a switch i.e. no one has connected to them and/or no traffic has been passed on them for some time?

Thanks in advance for any help.

10 Replies 10

IgorHamzic
Level 1
Level 1

Thanks for the replies.One more question.I have used the show command on one interface and in the last input line it displays the following:

FastEthernet6/2 is up, line protocol is up (connected)

Hardware is Fast Ethernet Port, address is 000f.90b7.d061 (bia 000f.90b7.d061)

Description: [--- telephone connection ---]

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

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

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s, link type is auto, media type is 10/100BaseTX

input flow-control is unsupported output flow-control is unsupported

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

Last input 16w4d, output never, output hang never

There is a PC connected to the port but it says the last input was over 4 months ago.Shouldn't the last input line show a much smaller value, probably in seconds?

Interesting, are the input/output packets increasing ?

Yes.

74 packets input, 9152 bytes, 0 no buffer

Received 2 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

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

0 input packets with dribble condition detected

2223 packets output, 222022 bytes, 0 underruns

After a couple of minutes:

188 packets input, 38164 bytes, 0 no buffer

Received 3 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

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

0 input packets with dribble condition detected

5286 packets output, 494429 bytes, 0 underruns

Also I just checked a Cisco 4500 and I see the same thing happening. I checked a port where just recently a PC was added and is working.

It shows also that the last input was some weeks ago but the input/output count of packets keeps rising.

That's odd, then the Last input entry is meaningless. I'll have to investigate on that. In the meantime, I suggest you follow my other recommendation and clear the counter, wait a few weeks then check for ports with 0 packets.

Already did it on both 2960 an 4500.I'll wait a couple of weeks than see what's happening with ports.

I agree that the last input entry is meaningless if it doesn't display proper values.

ankbhasi
Cisco Employee
Cisco Employee

Hi Friend,

I cannot recall any short cut to get the details of all ports at once. Yes you can issue a command "sh interface " to get the last input timer status.

GigabitEthernet1/0/3 is up, line protocol is up (connected)

Hardware is Gigabit Ethernet, address is 0018.186e.7d83 (bia 0018.186e.7d83)

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

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

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX

input flow-control is off, output flow-control is unsupported

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

Last input 00:00:23, output 00:00:01, output hang never

In last line of the output where it says last input 00:00:23 this explains number of hours, minutes, and seconds since the last packet was successfully received by an interface.

In interface is in down down status it will show last input never.

HTH

Ankur

Ah ! Great input there Ankur. I totally missed the last input|output field on the interface output.

With that said, the OP can issue.

show int | i Fast|(Last input)

a 2960 won't keep this kind of info but if you ever need it on a 4500 just use the "show interface link " command and this will show you the last time it was used.

Edison Ortiz
Hall of Fame
Hall of Fame

I'm afraid the switch won't keep historical data as to the last time the port was used.

My only recommendation is to clear the counters now, wait couple of weeks, then run the following command:

sh int | i Fast|0 packets

This command will display all interfaces in the switch that have 0 packets (in/out) since you last cleared the interface - which means those ports have not been used for that duration.

HTH,

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