I have gone through various documents on UDLD, Loopguard etc, with Rapid STP, normal STP .... Just wanted some kind of confirmation/validation here:
1) UDLD aggressive - will be enabled globally for IOS devices.. for Cat OS it is enabled per interface, as it cannot be enabled globally.. ( cat OS has UDLD normal mode in global mode).. i have also gone thro various scenarios - like enabling UDLD aggressive on one side,and the other side having normal mode or no UDLD enabled !UDLD can be enabled with no issues on one-side.. UDLD normal puts the port on inconsistent state, and UDLD aggressive err-disables the port.. Is that right ?
2) UDLD aggressive with Rapid STP - UDLD takes 45 secs to detect unidirectional link (15 sec message time), and 8 more secs.. With Rapid STP the convergence time is less and UDLD might not be useful in this case .. even with lowest message time 7 secs, it takes 21 secs to converge ... we can then use loopguard to detect unidirectional link with RSTP .. Is that right ? I saw a lot of posts from Francois about UDLD and Rapid STP timers which is of interest...
3) loopguard - as said above, loopguard will be used to detect unidirectinal links with RSTP.. when enabled globally, it enables loopguard on all ports (root, desig, blocked) etc.. is this fine ? also, how much time (in secs) will loopguard take to put the port on "loop inconsistent" mode.. are there any timers involved with loopgurad ?
4) Rapid STP with PVST on other side - when migrating PVST to Rapid PVST, we can have situations where we have Rapid STP in one side, and PVST on other.. In this case the network will work with normal STP timers (50 sec) convergence.. and UDLD would work good in this case.. Is that right ?
5) best practice - enabled loopguard & udld globally on all ports, whether the STP is rapid or PVST, or the switch is root or designated.. is that right ?
Hoping to hear..