I have about 20 RS6000s and 4 cisco routers on my ring. Under certain conditions where the ring is forced to renegotiate token rotation time or to enter a beacon state (ring-wrap) several times in a fairly short time, the fddi protocol stack and the IP protocol stack seem to disconnect from one another. After 22 minutes the stacks reconnect and things run fine again.
If you have the command 'fddistate' it shows that the fddi interface on the RS6000 is running fine yet you can not send any IP out that interface. The other systems on the net do not report ring wrap and show the 'disconnected' host still operating corrrectly as far as the fddi layer is concerned yet there is no response to any IP traffic.
