05-11-2009 04:53 AM - edited 03-06-2019 05:39 AM
Hi I wish to config vtp pruning but only on some trunks. i have 70 vlans and only want vlans 1,42 and 666 active. Please can some confirm this is the correct method:
Core switch:
switchport trunk pruning vlan add 1,42,666
Does this by default stop all other vlans?
Access switch:
Do i do any configuration on this?
05-11-2009 05:15 AM
You can prune on trunks, but you must perform the commands on both sides.
You need the command on the CORE and the access switch also.
That will limit the vlans traffic passed to the ones you have configured.
05-11-2009 05:20 AM
Hi
Thanks for this just to confirm this command is all i need to allow the vlans mentioned. I do not wish to enable pruning on a global level and only want to allow the once stated.
Can you also confirm the command is as i believe: allowing the access for the vlans?
05-11-2009 05:28 AM
Vlan pruning is a global setting. And if you only want to allow certain vlans on certain trunk links then vlan pruning is not the correct approach.
To control which vlans are allowed on the trunk link you should use the "switchport trunk allowed ..." command on both ends of the trunk -
Jon
05-11-2009 05:38 AM
Hi
Do i need to apply this command:
switchport trunk allowed 1,44,666
On both sides of the trunk i.e the core and access?
I assum restricting vlans this way
still improve the network performance ?
05-11-2009 05:46 AM
It depends on what is allowed on the trunk already. Using the switchport allowed vlan add command only adds to the existing list so assuming all vlans are allowed you need to remove most vlans from the link.
switchport trunk allowed vlan remove 2-43,45-665,667-1005
on both ends of link.
Note you can check which vlans are allowed by doing "sh interface trunk". I would recommend making the change out of core production hours.
The other way to do it -
switchport trunk allowed vlan remove all
switchport trunk allowed vlan add 1,44,666
again you definitely need to do this out of hours.
Jon
05-11-2009 06:31 AM
Hi please review the below i entered:
switchport trunk allowed vlan remove 2-43,45-665,667-1005
on both ends of the core and switch
switchport trunk encapsulation dot1q
switchport trunk allowed vlan1,44,666,1006-4094
switchport mode trunk
Port Mode Encapsulation Status Native vlan
Fa2/0/48 auto n-802.1q trunking 1
Port Vlans allowed on trunk
Fa2/0/48 1,44,666,1006-4094
Port Vlans allowed and active in management domain
Fa2/0/48 1
Port Vlans in spanning tree forwarding state and not pruned
Fa2/0/48 1
the remove all does not work. does the above look correct?
05-11-2009 06:40 AM
"Port Vlans allowed on trunk
Fa2/0/48 1,44,666,1006-4094"
Okay, you also have extended vlans on your trunks so
switchport trunk allowed vlan remove 1006-4094
then only vlans 1,44,666 should be left which is what you want.
Note that according to the output -
Port Vlans in spanning tree forwarding state and not pruned
Fa2/0/48 1
you don't actually have a vlan 44 or 666 at the moment.
Jon
05-11-2009 06:51 AM
Excellent thanks i am on a test lab just checking what performace issue i may have when adding and taking away vlan's. Are you aware if this change could riple the whole network or just the connection from point to point trunk to trunk?
05-11-2009 07:11 AM
I don't have a lab to test with but removing vlans from trunks could well have a knock on effect to STP and cause recalculations, hence the reason i suggest out of hours.
Jon
05-11-2009 07:14 AM
This could cause me a slight problem as we make vlan changes on a daily basis and need to do this during working hours. Would pruning provide me with the function on applying changes during the day. I would like to have some kind of control and not let this be a automated thing?
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