Conference netcad::hub_mgnt

1530.0. "CRC-errors from DEChub 900 ?" by COMBAT::JONSSON (Lars Jonsson) Wed Oct 05 1994 13:27

Hi friends,

I saw a very strange behaviour on a DEChub900 at a customer site this week.
The hub is configured with 3 IMB-channels. A DR900FP receives tre separete
ethernets from fiber and connects these to the IMB's. Channel 1 has 1 DR900TM
connected. Channel 2 has 3 DR900TM connected and the third channel has 1 
DR900TM connected. Also, there are a DS90L+ and a DR90C connected to the 
thinwire channel. The Thinwire channel is connected to the third IMB via 
the DR900FP. I was very careful to check that no loops were configured.

Similar configurations where performed, using hubwatch, on 6 other hubs.
When machines where connected to the DR900TM's, I noticed that they started to
logg block check errors. I had no network analyser at hand, but the customer 
had an Macintosh application called Etherpeak, which showed us approximately
1 % CRC-errors on two of the segments. Repeater counters on this hub looked OK,
but the DR900FP that connects to this hub, showed CRC and alignment errors.
After changing fiber, tranceiver cables, UTP-tranceivers without any luck, we
rebooted the hub (power cord out&in).
This cured the problem ! No more errors logged from the machines, no more 
CRC-errors from Etherpeak. Both segments looked very OK.

What happened to the hub ?
Has anyone seen anything like this before ? 


Regards
Lars