Alcatel Unleashed

Dear,

I discovered a strange behaviour with our stack of OS6850E (4 unit - AOS 6.4.5.474.R02).

The "show stack topology" correctly return Primary & Secondary Unit.

What would be from your point of vue the normal behaviour if we power down the Primary unit?

For your information we have multiple LACP links & a small loop (4 Switches).

The convergence time took around ~4 minutes which looks really long from my point of vue but maybe I'm wrong?

Thanks in advance for your help

Best regards

It may relate to mac-retention (or better change of mac-addresses when primary fails)

please test with
"mac-retention enable" and see whether it converges faster.. It may also be a good idea to do a controlled "takeover" before just powering it down.

devnull,

Thanks for your prompt reply

It's exactly what I was thinking... yesterday I saw that the MAC of the bridge change after the failover.

We have so a complete STP calculation and also saw that some Linkagg failed and need to be re-establish

I will also start a SR to have a position from ALU support

By the way it would be very welcome to have other experience in such scenario... So you think that 6450 have the same behaviour?

Best regards

Also it seems that this command is not supported on AOS6.4.5 ?

Best regards

I think it is pretty standard for stacks to use the mac-address of the primary.
If the primary changes it will use the new primarys mac-address.

6450 in stack-mode behave the same (btw. cisco switches as well).

I would always enable mac retention per default. Only caveat: When you exchange the primary (and reuse it at another place in the network) you will have duplicate MACs in your network which will create a mess..

So: never reuse a ex-primary switch without setting mac-retention to disable on his former stack and verify that the mac has changed. (and reenable it afterwards)

Linkaggs use the MAC-Address for LACP, so if the MAC changes the LACP will be gone until it renegotiates. Therefore STP recalculations take place.

edit: "mac-rentention status enable" was at least mentioned in 6.6.3 Manuals also in 6.4.5 manuals

Hi devnull,

For your information we did a new redundancy test yesterday evening. Before the test we added the mac-retention command

Convergence is now ~1sec inspite of 3 minutes !

Thanks again for your help !

We did the same test on 2 POD (6900-X40) and result is also perfect (no packet lost)... By default the command is enabled on 6900 when you create a Virtual Chassis

Thanks again !

Thanks for feedback..