VTP Pruning

[jmckechnie]

Hi,

I'm currently running a simple VTP domain with four swicthes (as attached). And would like some advice on VTP pruning.

My understanding is I would enable it for the whole VTP Domain on my server switch using the command below?

VTP_Server_Sw1(config)# vtp pruning

I have also read about pruning on the trunk links using this command?

VTP_Server_Sw1(config-if)#switchport trunk pruning vlan [Word] [add] [except]

If i did this am i right in thinking i just need to specify the VLANs carried trunk link on the trunk ?

So for switch 1 i'd just need to specify Vlan 2, Switch 2 Vlan 3 and Switch 3 Vlan 4?

Also should I enter the command at both ends of the trunk?

Thanks

J Mac.

[andrew.prince]

Yes - you configure pruining via VTP, and you configure it on the VTP server for the domain.

Yes you could do this - but to be honest in the topology you have, it's not required; but good to play with if you wanted to.

HTH>

[ibrunello]

Once you set vtp pruning on the VTP domain, it figures out by itself whether to prune or not a vlan.

Filtering vlans is usually achieved w/ "switchport trunk allowed vlan "

I usually set the above filter, and then allow pruning to remove any vlan that is included in the above range (thus maintaing the desired security), but not effectively used.

I see no vantage in forcing pruning behaviour, instead of setting expicitly with "allowed vlan".

Could you make a sample where it could be useful?

[andrew.prince · Accepted solution]

I personally would consider it when:-

1) I have more that 5 switches

2) I have a core/distribution/access topology

3) My topology is not flat and collapsed (1 core and 3 access switches)

At the end of the day pruning is used to improve LAN performance by cutting down on broadcast, multicast, unknown, and flooded unicast packets.

If your LAN is designed and configured to avoid these types of issues - then you will not need to prune, in my opionion.

HTH>

[jmckechnie]

Thanks alot very helpful, I've enabled it and rated.

Cheers

John

[andrew.prince]

np glad to help - thanks for the rating.