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New Member

Configuring RSTP on Uplink Ports

I have Two Catalyst 2950 Switches, I connected both Switches through their Two Uplink Ports. Now I Want to run RSTP b/w these ports by doing this:

Config t>int gi 0/1> spanning-tree mode rapid-pvst

But this command not works and shown as "Unrecognised command?"

So how I can run RSTP on switch specific ports?

Regards to everyone...Shahid


Re: Configuring RSTP on Uplink Ports

hi shahid,

configure rstp in global configuration mode

try for

Cisco(config)#spanning-tree mode rapid-pvst+

i think this will work.

rate the post if it helps



New Member

Re: Configuring RSTP on Uplink Ports

Dear Devang, I thing I couldn't explain my problem. Actually the rstp command i.e.

spanning-tree mode rapid-pvst

runs only on the following way:

Switch#config t> spanning-tree mode rapid-pvst

But I think this command enables rstp on whole switch (i.e. on vlan1, which includes 24 ports +2 giga ports)....while I want to enable/run rstp only on gigabit ports..and do this like:

Switch#config t> int gi 0/1>spanning-tree mode rapid-pvst

It not works....unrecognized command.



Re: Configuring RSTP on Uplink Ports


Spanning Tree protocols are concerned with the topology of your switched network. As such, they should run thoughout the whole switch domain, not just on a single switch or a single link. That is why it is not possible to enable RPVST on a single interface. The STP is a global function of the switch.

Yes, Cisco do allow you to disable the STP BPDUs on a single port, but in my experience it is risky to do so. It is always best to run STP on all your switches.

As for the interoperability between switches running RPVST and PVST, that is normally OK. The convergence generally falls back to that of the slower protocol.

In your case, are the 24 ports all access ports? If so, you could disable the SpanningTree BPDUs on them by applying bpdu-filter. But beware that any user could bring down your network simply by connecting a cross-cable between two such ports.

Kevin Dorrell


Re: Configuring RSTP on Uplink Ports

Hi Shadid,

Is it that you want to run rstp on the uplink but plain stp on the other ports?

Rstp is able to adapt its bpdus on a per-port basis, so even if you have switches running stp on the access ports, rstp will work fine there by sending stp bpdus. So changing the mode globally should be fine.

Let us know exactly what you are looking for if this is not what you were concerned about.



Re: Configuring RSTP on Uplink Ports


from the output of your command its clear that you can enable RSTP on whole the switch but not on the perticular port, so if you can specify your scenario with your requirement, so from that we can find out solution as per your need.

rate this post if it helps



New Member

Re: Configuring RSTP on Uplink Ports

Thanks for helping me…

As you told that RSTP is a global function and it can’t run on specific port, so it means when I run “spanning-tree mode rapid-pvst” command then it enables RSTP on all 24 ports but will it also enable RSTP on Gigabit/uplink ports?

Lastly I want to discuss my Network topology on which I will run RSTP…I have Six 2955T-12 Industrial Grade Switches. Two of them are Core Switches (using Two switches to provide redundancy in case of one Switch failure) and Four Switches are Access Switches for LAN1 and LAN2 (Again for LAN1 we using two switches for redundancy and same for LAN2). We will connect all Switches to each other with their Uplink Gigabit ports.

But remember we will test this topology in Tree as well as in Ring topology to find the lowest RSTP re-convergence time. One more important thing is that both LAN’s Computers (i.e. LAN1 and LAN2) have Dual LAN cards so that they will be connected with their both access Two Switches with Two LAN cards (we using Two LAN cards in Computers b/c of redundancy)

Now can you tell configuration of RSTP (also we should run on whole switch or on specific ports) and on which switch I should run RSTP in case of Tree topology and if possible in case of Ring topology (actually we want to test to find which topology will give the lowest RSTP reconvergence time)? Also I want to know that how we can run/enable RSTP on only Uplink Gigabit ports?

Also can I create Two or three VLANs in Catalyst 2955T-12 Switches but all VLANs should be Up?



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