dot1q and pvst+ region

Unanswered Question
Aug 16th, 2008
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hi everybody!

let say we have 3 switches with 4 vlans, running pvst+. switches have to connected by dot1q trunk only.

I read somewhere dot1q requires cst so how we connect switches running pvst+ by dot1q trunk?

thanks a lot!

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802.1q does not support PVST+ natively, however Cisco switches do support PVST+ over 802.1q trunks. So with "all" cisco switches and PVST+ (which is the default) everything will be ok.

When you use cisco switches with non-cisco switches, you must use a 802.1Q trunk, that will support CST (Common Spanning Tree), with 802.1Q into a CST region, only one instance of STP runs over the native VLAN, and one STP topology is used for all VLAN's.



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