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2810 STP Problem

CraigScott
Occasional Contributor

2810 STP Problem

Hi All,

Wonder if you can help.

As I understand the procurve switches, when calculating Spanning Tree do not take into account VLANS. The Procurves are blocking several ports as there is a physical loop (although there is no logical loop due to the vlan configuration).

I ahve read I should implement multiple instances and assign the relevent vlans, enabling each of them to choose the correct path based on their priority etc.

I cant however get this to work! one of the ports is labeled as the "master" when looking at the spanning tree instance configuration. If I look at the IST configuration its the same port that leads to the STP Root.

I have attached a very bad and simplified diagram of the setup of just one of the VLANS. The 2810 sees the physical loop and ST blocks the port going to the layer 3 switch.

I have created 2 instances, one that contains VLAN 1 and another that contains VLAN2, however changing the priorities of the insatnce containing VLAN2 has no effect.

Edit - To simplyfy matters, we can ignore the 2510 for now, once I know how to get the 2810 working it shouldnt be an issue!

For reference, the Nortwl switch stack is the Spanning Tree root (and needs to remain)

Thanks in advance,

Craig
1 REPLY
Richard Brodie_1
Honored Contributor

Re: 2810 STP Problem

Here's a good tutorial on MSTP: http://blog.ine.com/2008/07/27/mstp-tutorial-part-i-inside-a-region/

When you have a triangular arrangement, and have a link filtered in a VLAN, you need to make the root switch for the instance the one opposite that link. All its (non-redundant) links will be active.

So, in your example (mapping VLAN 1 to instance 1, and VLAN 2 to instance 2) you would need the Nortel to be the root switch for instance 1 and the Dell to be the root switch for instance 2. You can do that by lowering their priorities for that instance.

Now, you only have the instance trees within a single MSTP region. To set up a region you configure the switches with the same: configuration name+configuration version+VLAN to instance mapping. So you would need to do this on the Nortel, Dell and HP boxes and hope their MSTP implementations interoperate properly.

Even with your simplified diagram, this is sounding a bit nightmareish. So, I might consider foregoing spanning tree on a few links (say the uplinks to the Layer 3 router), set them bpdu-filter to lock them in forwarding mode and leave it at that.