Cisco Fddi Problems

Cisco Fddi Problems

Post by 25833-Mallesh Mariswa » Wed, 09 Nov 1994 02:00:33

We have an FDDI ring connecting 3 buildings. We have 5 Cisco AGS+ (Two of which are
runnign CCTL2) and 2 cisco 7000 attached to the FDDI ring. Each of these routers have
several ethernet interfaces.

Recently, we are experiencing performance problems with Appletalk protocol. A 1.8M file
takes more than 3 minutes, when it travels thru ethernet to an AGS+ (cctl2, FCI microcode
10.2) on to the FDDI ring to an a CISCO 7000 (running 10.0(4), FDDI microcode 10.0) to
a novell server with appletalk sharing on the ethernet. File transfers using IP and IPX
work fine taking the same path.

We started noticing this when we upgraded one of our AGS+ routers to a 7000.
Any help in debugging this is greatly appreciated.

Mallesh Mariswamy


1. Cisco FDDI problems with old and new intfcs?

We haven't had any response from the TAC (case A86101) on this
question, so we thought we'd ask a wider audience.

Question: Has anyone else seen problems with a mix of old and new
Cisco FDDI interfaces that have caused interface shutdowns?

Our problem: A backbone FDDI ring that has only Ciscos connected to it
had one router that went into beaconing and interface shutdown when
another router had a FDDI interface become wedged.

There are two failures going on: an FCI FDDI interface failure in one
router (AGS+) which apparently causes an FIP FDDI interface in another
router (7000) to go into beaconing and then shutdown.

Details on the FCI problem (1st failure):
The FCI FDDI interface in an AGS+ is apparently prone to
random failures where the interface just hangs.  It *says* it is up
and you can ping the interface address from the router, but you can't
get to any other ring address through the interface.

When we first reported this problem (summer 1994) the TAC had us
replace the FCI board, the FDDI applique, upgrade all microcode in the
box (FCI, cBus, MCI) and upgrade the system software.  Result: the FCI
interface still hangs on random intervals.

The TAC then recommended that we clean up the Ethernet error rates on
the segments attached to this router to reduce the rate at which the
FDDI interface hangs.  This worked (!) and kept the FCI interface from
hanging up again until Jan 25.

Details on the FIP problem
When the FCI interface failed again a week and a half ago an FIP
interface on a router several nodes away on the ring then went into
beaconing and finally shutdown, causing a backbone network outage for
that site.

When the FIP went into shutdown it put the bypass switch on that
router into bypass mode and the fiber optic path was bypassed onto the
next router.  This path continued to work, which argues against a
fiber problem.  As does the fact that the router has been operating at
this site for a long time without problems.  Nor can we find any
problem with the bypass switch or jumpers associated with the router
that shutdown its FDDI interface.

It appears that the hang up failure of the FCI FDDI interface is
somehow capable of causing beaconing and shutdown in an FIP FDDI
interface.  We're wondering if anyone else has seen this happen?




Charles Spurgeon                Campus Networking

(512) 475-9265                  Room COM1, Austin TX 78712

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