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Blocking BPDUs and interoperability between PVST and MSTP networks.

 
jstew
Occasional Contributor

Blocking BPDUs and interoperability between PVST and MSTP networks.

Need to determine the best/quickest way to solve this issue.  Our campus has two distinct networks serving two different needs.  Our production network is end-to-end Procurve with a mix of 8400, 5400, 3550, 2910/20, etc...  The default spanning tree config is MSTP that includes all vlans (~25 total vlans).  The secondary physical network which is used for video/audio consists of all Cisco gear primarily Catalyst 2950/60s and was installed by a third party vendor.  Over the past several years their have been more inquiries to provide services to the A/V network, from our production network.  The current request is to stand up a couple of VLANs to share services on.  My concern is I don't want the A/V network influencing the production network spanning tree topology.  I know there is VLAN overlap on both sides and PVST and MSTP aren't compatible.  Is there a way to allow both networks to coexist without forcing the third party vendor to change the Cisco gear to MST configuration or a massive undertaking for our internal team.  Our long term goal is to still allow the 3rd party team to manage the Cisco network, so keeping well defined lines of demarcation is preferrable if possible.  Thanks for the help and look forward to the responses.

2 REPLIES 2
HP-Browniee
Respected Contributor

Re: Blocking BPDUs and interoperability between PVST and MSTP networks.

Hello

You can disable spanning tree on the interfaces between the 2 core switches (Cisco core and HP core). In that case you will keep the 2 spanning-tree topologies.

This only works of course if all the access switches are only connected to 1 core switch. The cisco access switches on the Cisco core and the HP access switches on the HP core.

jstew
Occasional Contributor

Re: Blocking BPDUs and interoperability between PVST and MSTP networks.

Thanks for the reply.  I'm not sure I fully understand your response.  Are you stating that as long as all access switches are "physically" connected to the core or "logically".   In the case of this network, each building has a switch that distributes out to access, but all paths lead back to the HP core ultimately.  I can't comment on Cisco network yet, still waiting for that informaiton.  Handoffs would need to be made in several network closets throughout multiple buildings between the Cisco and HP networks.  So does this idea work in this case.  Does disabling spanning tree on interfaces cause them to ignore BPDUs from either network?

What about creating a new MSTP instance, set a high priority, and add necessary VLANs?  Would that shield the rest of the network?  I'm trying to brush up on spanning tree knowledge as I've never encountered different vendor network that I didn't control.  Sorry if this is elementary questions.  Thanks for the help!