Cisco Support Community
Community Member

Why does Rapid PVSTP mess up everything?

Here is the scenario:

When havin only the default VLAN everything works fine.

when making a VLAN (Lets say 10) and choosing another switch for that VLAN as the Root Bridge (picture 4 the red line) it messes the whole network up.

any ideas where to begin?


Why does Rapid PVST mess up everything?

Check out the Trunk link configuration on each switch and make sure that the created VLAN allowed by those Trunks.

and could you please give more details about the mess

like a snapshot of "show spanning-tree" command


Posted by WebUser Saif R. Abdulkareem from Cisco Support Community App

Community Member

Why does Rapid PVSTP mess up everything?

Hi, and thanks for the reply!

I checked the info, on all trunk ports all vlans are allowed, everywhere it looks like this:


Switch#show int trunk

Port        Mode         Encapsulation  Status        Native vlan

Fa0/1       on           802.1q         trunking      1

Fa0/2       on           802.1q         trunking      1

Fa0/3       on           802.1q         trunking      1

Fa0/4       on           802.1q         trunking      1

Gig0/1      on           802.1q         trunking      1

Gig0/2      on           802.1q         trunking      1

Port        Vlans allowed on trunk

Fa0/1       1-1005

Fa0/2       1-1005

Fa0/3       1-1005

Fa0/4       1-1005

Gig0/1      1-1005

Gig0/2      1-1005


and I checked the spanning tree, and if I have the default VLAN 1 and nothing more than I have a Root Bridge selected, but when enabling Rapid PVST there is no Root Bridge for any of the VLANs.

I think Peter might be right, it can be related to Packet Tracer.

Thanks again, and if you have any other Ideas, I would appreciate it!

Cisco Employee

Why does Rapid PVST mess up everything?


If you are testing this in Packet Tracer then be warned that the STP/RSTP simulation behaves strangely and often incorrectly. In general, Packet Tracer is a great teaching tool but the STP/RSTP in PT is notorious for behaving incorrectly.

Best regards,


Community Member

Why does Rapid PVSTP mess up everything?

Hi Peter,

Yes it is in PT. unfortunately I cannot test it for real, gut seems if you are right i must get the real thing and not virtualize with Packet Tracer.

Still, not giving up, but thanks for the feedback, this was the first idea that came in to my mind, that somehow PT cannot manage it.

CreatePlease to create content