need help linking 2 corebuilder 9000's together through fiber cable.they have been linked before, communicated for several days,one night they stopped.replaced modules,new cables,maybe a setting i'm missing.i dont know.tried autoneg on/off,flow control on/off ports are enabled.i get green led it seems each switch recieves and transmits packets.but i cannot ping each other or pick up the ip on #2.#1 is running the network fine.