Please check the figure 27-1 in: http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/12235se/scg/swudld.htm, regarding UDLD operation:
1) In the failure event, why Switch "A" doesn?t disable its port based only in Layer 1 mechanisms included in gigabit ethernet standard? what is missing in the standard? That means port in switch "A" is always UP? Why?
2) Assuming switch "A" doesn?t disable the failed port (for some reason, no UDLD support), is there some way for Switch "B" to detect the remote failure? Then, is it port in Switch "B" always UP?
3) Do you know some group, working around the standardization of UDLD?