Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

6509 STP issue


we have two 6509 in VSS with STP configured.

from each 6509 there is a link to service provider but to different office(equipment) of provider. one link is designated forwarding, another link is designated blocking. when i shut down the first interface, then second interface becomes designated forwarding, but when active 6509 is powered off then second interface doesn't become forwarding, it is stil stays in blocking mode. second 6509 became active also, but only link to provider not became forwarding.

is this normal?


6509 STP issue

You should use the STP features like :

So not to wait all the seconds you need otherwise. If you share the topology or some info more about your links termination maybe be i can help more


New Member

6509 STP issue

Hi Alessio,

what kind of information do you need? the topology is like this. interfaces are trunk ports with RSTP configured

on ISP side alcatel equipment used

if you need additional information please ask

6509 STP issue

Wouldnt you want to use a flavor of FHRP and track yor interfaces for this? 


6509 STP issue

I have no experience with VSS configurations, but I wonder why there is a blocking link in the first place. Is your root bridge on the provider side of the network? Are you sure your provider is using RSTP as well? If not, it could in fact take the tripple forward delay timer until your remaining link transforms into forwarding mode.

Away from your question it is probably a good idea to switch to a layer3 connection in this case.