Hey Guys,
This is a really basic question and I should know the answer. I am just pondering over loop guard and UDLD and take this for example: Two switches are connected via a pair of fibre (Tx at one end RX at the other). Now let's say the TX path from switch1 (RX on switch2) fails or is disconnected but the other fibre is still operational. I would have thought that logically Switch 2 should see that it is no longer receiving "light" on the cable and bring the port down? Obviously this is not the case. Therefore my question is what determines if a port is physically "UP"? What physical checks are done by the switch port and how does it determine if media is attached? Is a frame received over the fibre initially which brings the port up but a subsequent failure will go on undetected? Any reference links would be great J Thanks group. Aaron. _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
