UDLD works well when you've got a L2 switch with distributed processing, such as a 6500. We've had cases where a Sup was failing, perhaps due to overheating in a failed air conditioned closet. It failed to the point BPDUs were no longer being sent, but forwarding was still working. I guess the SP wasn't happy, but PFC still forwarding. Loop results. UDLD fixed that issue. We did that prior to spanning tree loop guard existing. I think loop guard can replace UDLD in some cases.
Chuck -----Original Message----- From: cisco-nsp [mailto:[email protected]] On Behalf Of Sebastian Beutel Sent: Wednesday, March 23, 2016 7:21 AM To: [email protected] Subject: [c-nsp] necessity of nowadays Hi List, i've been pondering about the real need for udld nowadays, each time it bites me in a case of false positive. At least since we have gigabit SFPs it became almost impossible to willfully provoke an unidirectinal link: The physical port allready detects missing light and goes down. Moreover, the main use of udld (prevent unidirectional loops in an stp topology) has also lost importance since link aggregation has replaced load balancing via multiple or per vlan stp topologys. That's why i am asking myself whether udld is a residue that nowadays causes more harm than it prevents and should therefore not be used anymore. At least on gigabit and faster links and if there are no really dumb media converters involved. What do you think? Best, Sebastian. _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
