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spanning-tree portfast trunk

I'm having doubt about a config that I'm not sure of...

I always tought that spanning-tree portfast sould be use on port that connect host (access)

Do you know why I would have this command

spanning-tree portfast trunk on a interace connecting 2 switch? Is it something desirable?

Merci,

3 REPLIES
Cisco Employee

Re: spanning-tree portfast trunk

spanning-tree portfast should be enabled only on access-ports that connect to workstations because enabling them on trunk ports could cause accidental STP loops. That being said there are situation in which you connect to end servers with a trunk port & you dont want that port to go through the usual 50 sec delay in STP state transistions. For such cases we can enable 'stp portfast trunk' on a trunk port which would cause the trunk to behave exactly as a access port connected to a workstation skipping the STP delay.

Hope that helps !!

Re: spanning-tree portfast trunk

I would recommend removing the command from the interface if possible. You could run into some serious problems in the future using portfast on an uplink. More than likely someone put it there for faster convergence when/if the link went down.

HTH,

Mark

Re: spanning-tree portfast trunk

I have to agree with Mark with an addition, if you want faster convergance in case of a primary uplink failure - then portfast it not the solution. You might want to consider running RPVST or enabling uplinkfast for fast convergance in a failure situation.

HTH>

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