Spanning-tree MST continued

Steven Peree · ‎04-23-2013

Hi,

We came at the point that we going to implement MST in our organisation.

Why?

Well we've bought new HUAWEI CORE layer switches (over 2 DC's) connected with DWDM.

Because the HUAWEI do not speak pvst+ or rpvst+ we are obliged to move to MST, well not exactly but to get the convergence time under 1sec we're thinking to migrate and offcourse to loadbalance a little

Huawei is speaking MSTP standard and our former core switches catalyst 4500 switches (which are now distribution layer) have been upgraded so they can talk MST as well according to the standard.

Because the region we're going to create will span two different sites, I'm wondering the following.

We have 4 catalyst 4500 switches beneath the huawei cores.

1. Do we need the trunks that interconnects the switches inside the region configure with all vlans allowed?

For the moment some dmz connections are only connected to 1 or 2 distribution switches and not all

And for the moment we have sometimes differnent trunks between 2 core switches with different vlans allowed on them

InayathUlla Sharieff · ‎04-23-2013

Hi Pereest,

If you read the implementation of MST its always recommended to allow the required vlans over the trunks ports in the MST region.

Below links might help:

http://blog.ine.com/2010/02/22/understanding-mstp/#MSTP_MULTI_SCENARIO3

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_example09186a00807b075f.shtml#diag

Hope that helps.

Regards

Inayath

Steven Peree · ‎04-24-2013

Hi Inayah,

Thanks for the info. Does this also mean that all vlans need to be known on each switch. For the moment that is not the case, but I believe that in case off failure an alternative path need te be taken and if a vlan is then not known on that switch, this won't work.

I'm I right.

It's just that for the moment the DMZ vlans are a little bit seperate by means of their own trunk, but I think that won't be possible anymore.

Regards

InayathUlla Sharieff · ‎04-24-2013

Hi,

Yes. As you know the MST instance to vlan mapping you need to have the proper vlan to instance mapping across the region and hence the vlans should be known to each other over the trunk to avoid any complexity of STP.

Regards

Inayath