[c-nsp] UDLD ?

[Jeff Fitzwater]

We have had a few strange unidirectional link problems and I thought  
that I could detect them using UDLD.   So I thought I knew how it  
worked.   I


I have a 6500 with a gig SFP LH mod connected to a 3750 with the same  
SFP.    I enabled UDLD AGGRESSIVE mode on bot ends and they both  
reported seeing each other as neighbors.

So I thought that if I disconnected one of the fibers that the UDLD  
would detect the unidirectional transition but instead both ends just  
reported link down.

I thought that breaking on side of the fiber would only bring down one  
end LINK since the other still thought it was connected.


I then disabled the UDLD and disconnect the fiber again and still had  
both ends show link failure.



Q>   So why does both ends go down?   Is this a new code feature for  
gig fiber ports or did I miss something?




Jeff Fitzwater
OIT Network Systems
Princeton University