Switchover of core switch - Root bridge transfer

[gjmallare]

Hi All

We are planning to decommision our old Core switch (non HP) and and totally switch over to our HP 5900 core, currently the old Core switch is our primary root bridge. What are the steps we need to do to transfer the Primary root bridge to  out HP 5900 switch and decomission the old core,to prevent or at least minimize down time if there is any? step by step guide if possible

Additional Information

• all of the connections are already on the HP 5900
• only a link between the old core switch and the HP switch is connected

Thanks for the help

[akg7]

Hello,

You can configure the root bridge as primary on new core and  set lower priority compare to old root bridge.

Please refer 'STP configuration task list' on pg.66 from below link:

https://support.hpe.com/hpesc/public/docDisplay?docId=emr_na-c03191756

Thanks!

[gjmallare]

Hi akg7

Thanks for the reply. Would there be anything we need to do on the old core switch? the old core switch is non-HP

[jmpk]

Hi @gjmallare 

There are couple of ways to set root bridge on HPE 5900 switch 

1. Configuring " stp root primary on HPE 5900 switch 

2. Changing the prirority on old or new switch, by default HPE switch use default priority  32786. So i suggest you to check and lower the priority on HPE 5900 switch 

When you changing the STP root from one switch from another switch all the traffic will be re-routed to new Root switch. But this won't be affecting users , since this will be un-noticable for the users.

Also you can refer our Layer 2 configuration guide and check " Configuring spanning tree protocols" on below link 

https://support.hpe.com/hpesc/public/docDisplay?docId=emr_na-c03191756

[akg7]

Hi @gjmallare,

I believe nothing required on old core. Priority should be less in new core compare to old core to elect as root bridge.

As my colleague @jmpk mentioned changing root bridge from one switch to another switch won't affect any users but all the traffic will be re-routed to new root switch..

Thanks!

[gjmallare]

Salamat (Thank you) for your replies @akg7  and @jmpk. So by unplugging the cable of the Old (non-HP) Core switch from the New (HP5900) core switch should not pose any issues, reconvergence should be quick and should not be felt by EU's and the New Core should act as the root bridge for the network once the old core has been disconnected?

[jmpk]

Hi @gjmallare 

Yes. Once you see the new 5900 take the role of root bridge you can start migrating the other services in your old core.

As always we suggest our customer to take this kind of changes in by taking necessary down time 

[akg7 · Accepted solution]

Hello,

Yes correct, unplugging the cable of the old core switch will not pose any issues if you made necessary changes like set lower priority in new core and set as primary..

Also new core should have necessary cable connections with other switches like old core.
Switches in the network will receive topology change notifications (TCNs).

Can you please share network diagram where old and new core connected and have port mappings?

Thanks!

[gjmallare]

here is the current and what we want to achieve (After).

Currently only the connection to the new core (HP5900) is connected to the old core.

The rest of the connection have already been transferred to the New Core switch,

the only thing remaining is removing the old core. Hesitation for this activity is if we cut the Old core is how long it will the new core re-converge  and become the Root Bridge for the network since they are not of the same brand (but as mentioned earlier, should not be noticed and should should have no effect on the EU and seems brand can be neglected at this point and should have no bearing). We will be doing the switchover in a few weeks, and right now we are just covering all possible risk and look into mitigations, just in case (hopefully all will go well).

[akg7]

Hello,

Spanning Tree follows the standard convergence time irrespect of brands.

Either set lower priority in new core switch compare to all switches in the network or set new core as root primary.

Thanks!