Udld, rstp and tranceivers

[DWAM_2]

Hello,

I search recommandations between :

UDLD and Tranceivers (copper/fiber).

UDLD and RSTP.

Thank you in advance.

Regards.

[benhur.p]

Not clear what you are looking for

[DWAM_2]

Hello,

I want to know if there are recommandations between udld and tranceivers (Cisco speaks about udld with fiber link but what are recommandations if we use udld with tranceivers copper/fiber : use udld? not use udld ? why ?)

and about udld and RSTP (majority exemples on cisco's site speak udld with stp 802.1q (especially tuning with timer udld)) Is there something to know between udld and RSTP?

Regards.

[Rodney-roberts]

I actually had a TAC case on that same subject and if you are using the same type of copper transceivers I used for some reason the UDLD packet was not forwarded out of the third party device. For some reason it stopped at the copper port and wasn’t passed thru to the fiber port.

this link maybe helpful

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_5_4/config/udld.htm

[skarundi]

UDLD works at layer 2, so if the transceivers make changes at the layer2 level, then i'm guessing this may affect udld. About udld and rstp, rstp would help because it would reduce the convergence time of the network. From my experience the longer the STP convergence time is the more likely it is cause a temporary bridging loop and cause udld to kick in and disable a link causing an unnecessary disruption.

[DWAM_2]

Hello,

Finaly , here are the actions about udld (validate with Cisco) :

All inter-switch links (copper / fiber without tranceivers) : UDLD standard mode.

All inter-switch links (copper / fiber with tranceivers): Udld aggressive mode (to avoid blackhole) with a solution of automatic recovery (like 120secondes)

We use tranceivers Allied Telesyn model Number AT-MC101Xl-20.

If we loose fiber link, the tranceivers does not detect that. and the copper link stay up...

I have seen with Allied Telesyn that it's a normal behaviour for this type of tranceivers.

Best Regards.