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can you tell when a port was last active
- Thread starter jdeane
- Start date
Probably the best way is to issue a 'show int fax/x' command where x/x is the port you want to look at.
You'll get something like the following:
Switch#sh int f0/1
FastEthernet0/1 is down, line protocol is down
Hardware is Fast Ethernet, address is 00d0.9751.ddc1 (bia 00d0.9751.ddc1)
MTU 1500 bytes, BW 0 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 100Mb/s, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:17, 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
1 packets input, 64 bytes
Received 0 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
6 packets output, 826 bytes, 0 underruns
0 output errors, 0 collisions, 3 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
The bits of interest in the output above are the bits that say "Last input never, output 00:00:17"
This tells you when traffic was last seen on the port. As you can see from my example, there hasn't been any input traffic and the last output traffic was seen 17 seconds ago.
Sometimes this approach is complicated by the fact if say a router or another switch is attached to the port in questions as it may be sending regular routing updates or something similar. Naturally this will ensure traffic is always being seen on the port.
Hope this helps
You'll get something like the following:
Switch#sh int f0/1
FastEthernet0/1 is down, line protocol is down
Hardware is Fast Ethernet, address is 00d0.9751.ddc1 (bia 00d0.9751.ddc1)
MTU 1500 bytes, BW 0 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 100Mb/s, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:17, 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
1 packets input, 64 bytes
Received 0 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
6 packets output, 826 bytes, 0 underruns
0 output errors, 0 collisions, 3 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
The bits of interest in the output above are the bits that say "Last input never, output 00:00:17"
This tells you when traffic was last seen on the port. As you can see from my example, there hasn't been any input traffic and the last output traffic was seen 17 seconds ago.
Sometimes this approach is complicated by the fact if say a router or another switch is attached to the port in questions as it may be sending regular routing updates or something similar. Naturally this will ensure traffic is always being seen on the port.
Hope this helps
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