From: Salau, Yemi (yemi.salau@siemens.com)
Date: Fri Aug 31 2007 - 05:52:38 ART
Just to add to this in a lay-man language that I understand :-),
vtp-pruning is an automated implementation of vlan-allowed list at trunk
boundaries. Basically, you're allowing/denying tagged frames as they
come in on that port depending based on vlan_id. But the good thing is,
I don't need to accept a tagged frame with a vlan_id which doesn't exist
on the Switch, so I "prune" such as it's coming into that trunk port.
Could do this via vlan-allowed list, but vtp prunning is the automated
variation of doing this.
VTP Pruning is still useful these days, trust me.
Many Thanks
Yemi Salau
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
NET HE
Sent: Friday, August 31, 2007 2:52 AM
To: thomas.rader@freesurf.ch; ccielab@groupstudy.com
Subject: RE: VTP Pruning
Give you an example, then you will understand it.
Let's say there are 3 switches linked by trunks in a VTP domain, switch1
as
vtp server, other 2 as vtp clients.
Switch1 has host A1, B1, C1 connected to VLAN 1, 2, 3 respectively,
switch2
has hosts A2, B2, C2 connected to VLAN 2, 3, 4 respectively, and switch3
has
hosts A3, B3, C3 connected to VLAN 1, 2, 3 respectively
After a period of silence, A1 is trying to ping A3, A1 first will send
an
ARP broadcast asking for MAC address of A3. If VTP pruning is not on at
switch2, you will see ARP message on the trunk between switch1 and
switch2,
switch1 and switch3. But if VTP prunning is on at switch2, switch2 has
already reported to switch1 saying that I don't have any hosts at VLAN
1,
please don't send any VLAN 1 traffic to me. Therefore you will only see
that
ARP message on the trunk between Switch1 and Switch3, not the trunk
between
Switch1 and Switch2.
Best Regards,
Net (Xin) He
>Hello,
>
>I've never really understood VTP Pruning.
>
>Sure I know that it reduces VTP traffic and is enabled using the "vtp
>pruning" syntax, but I've never seen this deployed in any networks.
>
>Has anyone got any experiences with this or can share light on this
matter
>?
>
>Thanks, Thomas
>
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