Latecoll error on router

[cbeazley]

I have a 2600 cisco router and have setup a syslog server.
This routers only function is to establish a vpn tunnel do a pix device.

I keep getting Latecoll errors on my inner interface and can't figure out why. I have tried adjusting full-duplex to half and set speeds to 100 instead of auto. I have replaced the cables and still get the errors.

I have now hooked up a packet sniffer and see that I get a lot of loopback frames from that device but loopback is not set in the config.

Any ideas anyone ?

 

[hexn]

Im not sure about loopback frames, BUT, late collisions is when the cable is soooo long that the interfaces learns about a collision later than the standard time.

Loopback sounds fishy. Perhaps its packets are looping all around in your network somewhere, and it eventually collides.

 

[tbilan]

Post the configuration for the interface and a show interface.

 

[cbeazley]

Thanks for your replies.

It is most certainly not a long cable. Perhaps I'll try yet another cable since most people are suggesting a cable issue but perhaps it's more to do with it being connected to a hub and not a switch. The thing is that I have a firewall and 2 switches connected to the same hub so it may be the root of the complaint.

I'll post the config later since I have killed the ability to telnet to it.

 

[svermill]

I would guess that almost certainly one of the devices attached to that hub is still set for full duplex. All devices would need to be half. Furthermore, connecting a single hub to multiple switches or multiple ports on a single switch can easily cause loops. Make sure you've thought out your layer 2 topology carefully.

 

[jgercken]

What exactly do you mean by loopback frame? A late collision happens when a device detects a collision after at least 64bytes have been received. The thought is that 64bytes worth of data is long enough so that every device on the collision domain should see it and not xmit. The error can be caused by a faulty nic or hub, a bad cable, interference, or using too long of a cable.

I would remove devices one by one from the network and see if the errors stop. Also look for sources of EMI interference like power lines, light ballasts, etc.

-Jeff
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[marsd]

Late collisions sometimes indicate full duplex errors.
Bad cable usually shows up with CRC failures and the like.

Post your config.