I want to find out if you can do manual pruning on trunk links on downsteam switches that are clients in my VTP domain, without enabling pruning on the VTP server? I have low end switches that have met the max STP instances and need to prune these port-channels to reduce the stp instances seen on these blade switches. Thanks, Ted
my understanding is that an STP instance is created and is executed until there is at least a physical interface (access port or trunk , this is the key point here) that is associated to the corresponding vlan (switchport access vlan x for an access port, or it is permitted in the trunk vlan list).
By editing the list of vlans permitted on trunk uplinks you are removing the only ports that are member of non-used Vlans.
As a result of this the switch should (after some time) stop and delete the unnecessary STP instances.
VTP plays no role in the creation of STP instances that are triggered by what I've described above.
VTP is just a protocol to advertise the existence of Vlans in the campus nothing more.
VTP pruning provides benefits on the forwarding of broadcast, multicast, unknown unicast over trunk links (if they allow all existing vlans) but not STP instances reduction.
I've given you an example before:
31 Vlans in VTP and only 17 STP instances running. This is where you have to go.
Hope to help