From: John (jgarrison1@austin.rr.com)
Date: Sat Jul 26 2008 - 12:38:36 ART
Peter,
VTP pruning stops flooding down trunks that have don't have the attatched
vlans. That implies that vlan information has to be passed between switches
pruned or not. Otherwise how would spann know if vlan 20 has been added to
a port on SW2, and now should not be pruned using your example. See this
for more info
http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_25_se/configuration/guide/swvtp.html#wp1035139
----- Original Message -----
From: "Peter Stephan" <engpeter@gmail.com>
To: "'Cisco certification'" <ccielab@groupstudy.com>
Sent: Saturday, July 26, 2008 6:23 AM
Subject: Spanning Tree / SVI / Trunk Allowed Vlan / Prunning
> Dear GS,
>
> While trying to order these technologies and correlate them, I found
> myself
> unable to understand some stuff which I'm sure we have to be sure of while
> taking the IE.
>
> I arranged this simple topology:
> SW1: VTP Domain CCIE, server, VTP prunning enabled.
> SW2: VTP Domain CCIE, client, VTP prunning inherited from server.
>
> In SW1, one interface is member of vlan 20, while in SW2 there's no vlan
> 20
> members.
>
> Interface fa0/13 dot1q between both switches with all vlans allowed
> initially.
>
> Seeing vlan 20 pruned from the trunk, I can still see the PVST vlan 20
> running in-between.
> (I expected to see the trunk not allowing even the BPDUs for STP vlan 20,
> which is not the case here, and the SVI yet UP and functional).
> But when I banned vlan 20 from the trunk, the STP got disabled and the SVI
> went down.
>
> Now please help me ensuring below concepts are correct:
>
> 1) SVI status is based on the spann vlan status.
> 2) Why prunning do not filter PVST BPDUs, when filtering a VLAN through a
> trunk.
> 3) When prunning, the pruned vlan appeared pruned from the upstream
> switch,
> but not on the switch who requested the prunning.
>
>
> Thanks guys and sorry for the long mail.
> Peter.
>
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Mon Aug 04 2008 - 06:11:57 ART