We are preparing to incorporate UDLD and Loopguard into our infrastructure, and are wondering if anyone can give advise as to UDLD normal or UDLD Aggressive.
It seems that UDLD normal, barring any initial miswiring (misconnected ports), will do nothing to block a uni-directional link, and will only block should it be triggered by a L1 mechanism. While Loopguard will see and block uni-directional links on receive portion of links carrying BPDU's, it won't block on the send portion of the same links as they aren't carrying BPDU's.
It seems that UDLD aggressive will block all uni-directional links, even if Loopguard doesn't catch them (black holed traffic as well). We've seen many suggestions, even from Cisco, that recommends using UDLD normal mode. We have also seen advisements in these forums that recommend the same. What are the 'gotchas' with using UDLD in Aggressive mode? We are currently leaning towards UDLD Aggressive and Loopguard being implemented in a 802.1d environment. We also plan to implement errdisable recovery for UDLD and set at 300 seconds.
Any thoughts or advice would be appreciated.