[comp.dcom.lans] Connecting DEMPR to Chipcom 8023

abstine@sun.soe.clarkson.edu (Arthur Stine) (02/09/89)

I am having problems with a DEMPR attached to a Chipcom 8023 broadband modem.
Every few hours, it seems to be jamming up and ends up crashing or hanging
the stuff which is attached to the one thinwire segment attached to the dempr
(a couple VAXstation-2000's, PCs, etc). SQE is turned off on the 8023, but
currently local AUI echo is turned on. I am unsure whether this causes a
problem. For the period of time up to the jam, there appear to be no problems
with the net (no excessive collisions, mis-aligned packets, etc). The situation
is somewhat complicated by having a DELNI attached to the 8023 via its network
port. Prior to attaching the DEMPR, everything worked fine. The only thing
that appears to pick up this 'jam' is the dempr. the thinwire line was
previously attached via a pair a DEREP-RC's with a short section of fiber
and while attached to the DEREP's, the thinwire never experienced this problem.

Does anyone have experience with DEMPR's in this sort of config? any
pointers or insight?

art stine
sr network engineer
clarkson u

haas@wasatch.UUCP (Walt Haas) (02/10/89)

In article <2440@sun.soe.clarkson.edu>, abstine@sun.soe.clarkson.edu (Arthur Stine) writes:
> I am having problems with a DEMPR attached to a Chipcom 8023 broadband
> modem...  The situation is somewhat complicated by having a DELNI attached 
> to the 8023 via its network port...

Feeding a DELNI into a Chipcom modem is a violation of the configuration
rules because the DELNI generates runt packets.  The broadband doesn't deal
with runt packets very well unfortunately.  Something like the LANbridge or
equivalent must be used to filter runt packets.  This might be part of the
problem.

Cheers  -- Walt Haas    haas@cs.utah.edu    utah-cs!haas