input errors problem

[lamaq]

I have a Cisco 1720 router that keeps giving me input error problems. Usually after about an hour or so the errors build up and the Internet connection is dropped meaning I have to reboot the router.

The setup of the network is: the router connects to a hub which in turn connects to a Nortel Contivity box and a Nokia IP330 Firewall which recently replaced my old firewall. When I connect the router directly to the firewall there is no input errors. I have checked the hub and the cables so there is no problem there.

Any help would be much appreciated.

 

[thebruge]

Lamaq can you be a little more descriptive, what input errors do you see? Can you send a "show int" from the router? Do you see any errors on the console?

 

[lamaq]

this is what i get from a show int f0:

FastEthernet0 is up, line protocol is up
Hardware is PQUICC_FEC, address is ********
Description: ******
Internet address is *******
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 00:26:13
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 56000 bits/sec, 27 packets/sec
5 minute output rate 402000 bits/sec, 41 packets/sec
53842 packets input, 23931195 bytes
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
44 input errors, 42 CRC, 3 frame, 0 overrun, 0 ignored
0 watchdog
0 input packets with dribble condition detected
64347 packets output, 60618046 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred


This has happened after only 20 minutes since I did a clear counters command.

 

[thebruge]

The problem could be the following:

- Full-duplex, 100Mb/s, 100BaseTX/FX

But you say that the router is connected to a hub, if this is the case then try and put the interface to half-duplex and see if this helps.

 

[lamaq]

Thanks, I'll give that a try.

 

[lamaq]

Still have input errors. I will check that the firewall and contivity box are not set to full duplex as well.

 

[lamaq]

I still get errors after changing the duplex settings on the firewall and contivity box. I should also mention that the router was working fine before the new firewall was put in and nothing has changed on the router configuration.

 

[thebruge]

The input errors on the router are CRC's so this means that the packets recieved at Layer 2 had the incorrect and are being dropped. Can you try a couple of things, move the firewall to another port on the hub, try another cable between firewall and hub, give the hub a reboot

 

[lamaq]

I've already tried all those things I'm afraid. I replaced all the cables and tried a couple of different hubs so I don't think that's the problem.

 

[thebruge]

What if you remove the Nortel box from teh hub, does this help?

 

[lamaq]

I can't remember exactly but I think it did stop all the errors when I dropped the Contivity off the network a couple of weeks back. I can't drop it now because there are people using the box at the moment. Somehow the new firwall is causing problems with the Contivity and/or router.

 

[thebruge]

Maybe on thing could be to put a sniffer on the hub and see who is sending the packets with a bad L2 size. It might help you track down the cause of the problem.

 

[lamaq]

I'll give that a try, thanks.