On Fri, May 19, 2000 at 02:45:33AM -0500, Ralf Schönian wrote:
>
>
> Dear specialists,
>
> we have a big problem in our token ring. I can see with Ethereal a lot
> of ring purges but I don´t know, how I can find out which station is
> the reason for this behaviour.
> Please, can someone give me an advice which steps I can do to
> isolate the error?!
>
> With kindest regards, R. Schoenian.
Look at your trmac packets that are Report Errors. (trmac.mv == 0x29)
Ring Purges are produced once there's a breakdown in the token protocol.
Hopefully you'll have an "Isolating Error" (see the trmac decode)
that tells you why the purge occurred. If the error is isolating, then
the fault domain can be determined from the trmac packet itself. (This
is why token-ring is *so* cool).
The trmac packet itself has a MAC address, and it has it's Nearest Active
Upstream Neighbor's MAC address (trmac.naun), which is the previous
active MAC address on the ring. The fault domain is somewhere between
the NAUN and the MAC address of the machine producing the trmac frame:
NAUN ----> cabling ---> TR MAU/switch ---> cabling --> MAC
>From my experience, I'd look first take the NAUN machine off the ring and
see if things get better. I've seen many TR cards go crazy, and they simply
have to be replaced.
For a good book on Token-Ring, I recommend:
NetWare LAN Analysis, Second Edition
Laura A. Chappell and Dan E. Hakes
(c) 1994 Novell, Inc.
Novell Press, San Jose.
ISBN: 0-7821-1362-1
Yes, it's a NetWare book, but it has some of the easiest-to-understand
explanations of how token-ring works that I've seen.
--gilbert
