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MST question

Hi all,

We have a site with MST deployed to load balance traffic for a small number of Vlans. There are explicit Vlan to instance mappings defined. I need to create a new Vlan that is currently mapped to instance 0, by default. 1 & 2 are in use for Vlans that span the network. The Vlan I need to create only needs to exist on my core switch. It does not need to span the network, just reside on the single switch. My question is this, as I don't have any test equipment to test this on, can I simply create the Vlan and leave it mapped to instance 0? Unfortunately the root bridge for this particular Vlan was dynamically negotiated, so the Layer 2 path is not optimal, but I figure this doesn't really matter as the actual Vlan does not need to be created on this switch. The Vlan is simply a simple broadcast domain that I wish to hang a service off. I don't really want to get into mapping this Vlan to an instance as this would mean reconfiguring all switches to just add a Vlan that only needs to exist on a single switch.

Can anybody please advise?



VIP Purple

MST question


The easiest way is to set the switch you want that specific vlan applied to vtp transparent mode this way the vlan creation will only be applicable to that switch and not propagated throughout the vtp domain.



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Community Member

Re: MST question

Thanks Paul, the switch is already in that mode. Didn't fully read up on MSTP before posting as I needed the information in a rush and couldn't recall if it used VTP to propagate information.

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