Token Ring Horror Troubleshooting

IANAC (I am not a CNE) but...
>Now the question:  What tools are available on the AS/400, short of
>buying a sniffer, which will help me check the health of our network. 

For a problem like this, it might be cheaper to find a local consultant
that already owns the appropriate tools, and knows how to use them, to do
the diagnostic for you.

>We may have a bad MAU, because a majority of the PCs reporting problems
>are connected to the same MAU, but how do I check?
One option is to play musical users.  Keep track of whos on the suspect MAU
"A" and thought-to-be-ok
MAU "B".  Swap all(or even just a sampling) of the users from the A to B
and see if the problem goes to the people who have been moved to the
suspect MAU or follows them to the new one.  (Hint:  Keep the patch cables
on the MAU following the end users; that way if there is a bad cable there,
the problem will follow the user.)

>Also, has anyone tried using two different brands of MAUs within the
>same ring?

Different brands should be OK if they are compatible.  IBM 8228s are
'passive'  MAUs.  I don't know about the
Andrew one you have, check to make sure it's passive not active, because I
don't think you can mix passive and active MAUs within a ring.    You said
it's supposed to be compatible with the 8228, but not how you determined
that.  Double check with their tech support, even if the documentation says
it is...typos happen. 

Did this problem show up when the Andrew MAU was added to the ring?  Or did
you previously have peaceful coexistance?

><snip> we run a combination of UTP and STP cables.  
I'm not sure if mixing UTP and STP on one ring is OK to do. Some cards have
to be told which they are attached to, might be better off to use one or
the other.  If you can't replace one or the other because of the amount of
each in existance, it might be easier (???) to split the ring into two
rings, one STP ring, and one UTP ring.  Might have to be careful with the
patch cabling if you go that route though.  STP is reccommended for IBM
products (at least that's what my Novell CNE Study Guide says.)  UTP at
16MBPS apparently doesn't work well in practice, so if possible replace it
with STP.  My aforementioned book says "...16 Mb/s Token Ring over UTP is
almost impossible to achieve."

And, if you haven't already, try reseating all the cabling & plugs on the
suspect MAU, including the ring in/ring out cables.  If some of the cabling
is homemade, and looks like it isn't well seated in the RJ45 plug or looks
like it got a bad kink/bend (the kind that might break wires internally,
resulting in intermittant contact), consider it suspect and replace them.

Hope that helps!

Ilena Ayala
Barsa Consulting Group
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