'clear int fa0/1' command on 2621 1

[chieftan]

Anyone know what might cause an interface to go into a kind of 'blocked' state where the 'clear int fa0/1' command causes it to work again?

Could it be a buffer issue?

 

[rainman]

The only reason that I know of that a switchport would go into a blocked status is due to a spanning-tree error (loop). Do you have two ethernet links that are going to the same switch and one is working but the other is blocking?


-Rainman

 

[3wsparky]

whats on the other end of this router , many routers if they detect dirty signals or unknown voltages shutdown to protect the network this can be caused by powercuts brown outs that sort of thing.

 

[chieftan]

Thanks for the responses so far:-

When I complete a show int command the following output is shown:-

FastEthernet0/0 is up, line protocol is up
Hardware is AmdFE, address is 000f.2442.9540 (bia 000f.2442.9540)
Description: ERAN internal i/f
Internet address is xxx.xxx.xxx.xxx / 24 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, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/32/1000/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/100 (size/max)
5 minute input rate 5000 bits/sec, 9 packets/sec
5 minute output rate 2000 bits/sec, 3 packets/sec
9693994 packets input, 895551918 bytes
Received 73526 broadcasts, 0 runts, 0 giants, 0 throttles
1 input errors, 0 CRC, 0 frame, 0 overrun, 1 ignored
0 watchdog
0 input packets with dribble condition detected
8930840 packets output, 1379364120 bytes, 0 underruns
0 output errors, 0 collisions, 14 interface resets
0 babbles, 13 late collision, 33 deferred
33 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

I realise from this output that there are a lot if interface resets, but am unsure of what this is telling me.

Can anyone help?

Thanks

 

[voltron1011]

Wow, there is something going on there. You've got resets, collisions, lost carrier errors. There is something dirty plugged into that port. What do you have plugged into it? A host? Another router or switch?

 

[chieftan]

I think I have found what the problem is.....

Well, not on this interface (I have posted fa0/0 and was meant to post fa0/1 which is even worse).
int fa0/1 is connected to a port on a 3550 switch, and guess what, the port it is connected to is set to FULL DUPLEX but the fa0/1 port is set to HALF DUPLEX.....would this be causing the problems?

 

[voltron1011]

Yes, this will cause massive problems. I would set both to auto-negotiate and see what they agree on.

 

[voltron1011]

If that doesn't work, I'd set them both to 100 full-duplex

 

[chieftan]

Thanks voltron.... I thought this might be the case