Re: DECnet phase IV node drops itself. Why? How?

From: AEF (spamsink2001_at_yahoo.com)
Date: 09/30/05 

Date: 29 Sep 2005 17:04:21 -0700

Colin Butcher wrote:
> When you talk of "redundancy transceivers" - what make are they? How do the

I'll check tomorrow. I'm at home and can't look at them now.

> transceivers make a decision to flip over which path they talk over - and
> back again? How are the switches the transceivers connect to connected to

I don't know.

> the rest of the network?

They are plugged into Cisco switches.

> Are they interconnected?

There are two jacks on one side of the transceiver. A cable from each
of these two jacks goes to a jack on each of two Cisco switches.

Do they have any special
> attributes to handle the path changes?

I'm not aware of any.

Have you made any changes to the
> DECnet timers etc. to accommodate the lower layer doing path switching?

No. AFAICT we are running with default DECnet values except for the
maximum no. of links which we set to 256 on all nodes.

 What
> else has changed in the network that may have introduced additional delays
> and latency to that path switch-over process?

London is preparing for a move to a new data center. We haven't been
kept totally up to date on what they are doing.

> Chipcom Online used to make such transceivers which work in conjunction with
> a special central pair of repeaters (usually star-wired to the transceivers
> and inter-linked).
>
> You've read the DECnet Phase IV functional specifications to help determine
> exactly what the errors you're seeing relate to?

Nope. I'm not an expert on the network side of things.

Please keep in mind that these systems are currently working fine. This
was only a problem for about 1 minute on a recent Sunday evening (see
original post, times are UTC (GMT)). There are no end users on the
system then.

Mostly I just wanted to know what it means that a node drops itself.
How can it do that? What does it mean independent of the structure of
my network? In particular, could it mean that the transceiver itself is
going bad? If that's a possiblity, I need to replace it -- especially
since this node (NODE_X) is one end of the DNIP tunnel to our New York
City VAX systems.

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