Proper STP deployment

[steff006]

So far we have rapid pvst running on our core and pvst, mst running on the access layer. We have turned spanning tree off on a number of vlans on the access layer because of the huge amounts of loops we had on the flat network that used to be in place. The reason for this was that STP would use too much bandwidth and cpu in order to crack down all the loops, so we turned it off in order to save bandwidth on the network. Now the flat network is gone and we would like to add spanning tree back into the access layer. What would be the proper way to deploy STP on the access layer while at the same time minimizing STP convergence time?? Any help would be great! We have 3550s and 3500XLs running the access layer.

[Georg Pauwen]

Hello,

it depends on how your access layer switches are connected to the distribution layer. If you have redundant links with blocked ports, you could use the uplinkfast feature. You might want to check this document for a detailed explanation of this feature:

SPANNING TREE PROTOCOL

Understanding and Configuring the Cisco UplinkFast Feature

http://www.cisco.com/en/US/partner/tech/tk389/tk621/technologies_tech_note09186a0080094641.shtml#intro

Then, obviously, disable spanning tree on all access ports:

Switch(config-if)#spanning-tree portfast

HTH,

Georg

[steff006]

Here is the spanning tree we have on the distribution switch

spanning-tree mode rapid-pvst

spanning-tree loopguard default

no spanning-tree optimize bpdu transmission

spanning-tree extend system-id

spanning-tree uplinkfast

spanning-tree backbonefast

Also spanning tree is running for each vlan in the network

Here is the spanning tree we have for the access layer

spanning-tree uplinkfast

spanning-tree backbonefast

spanning-tree portfast bpduguard

Along with spanning tree turned off with each vlan on the access switch

no spanning-tree vlan ####

My question, is there a need to turn spanning tree on for each vlan on the access switch, when it is turned on in the distribution layer switch?

[Georg Pauwen]

Hello,

it depends on the setup of your physical infrastructure. If you have redundant links between your access layer switch and your distribution layer switch, turn STP on, if you have only one uplink, there is no need to run STP.

HTH,

Georg