From: Scott M Vermillion (scott_ccie_list@it-ag.com)
Date: Mon Nov 10 2008 - 23:57:37 ARST
Hi Shahnawaz,
I am not entirely clear what your exact point of confusion is, but this link
describes the mechanics of VTP pruning pretty well:
http://www.informit.com/library/content.aspx?b=CCNP_Studies_Switching&seqNum
=26
It's an excerpt from a Cisco Press book. What it basically says is that
Cisco switches use "VTP Join" messages to advertise to directly attached
neighbors what their active VLANs are. In your example, since SW2 and SW3
do not have any interfaces in VLAN20, they will not list this VLAN in their
Join messages. Thus, that VLAN will be pruned off of the trunks.
Regards,
Scott
(Incidentally, outbound e-mail appears to be blocked at the office I'm
working from this week, so apologies in advance if this has already been
answered a hundred times before my mail all goes out the next time I connect
to my home network!)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Shahnawaz Khot
Sent: Monday, November 10, 2008 2:10 AM
To: Cisco certification
Subject: Confusion on VTP pruning.
Hi experts,
I have confusion on pruning. Please help with your expert suggestions.
Let's suppose for following topology.
SW1
- -
- -
- -
- -
SW2-----------SW3
All three switches are interconnected by trunk links.
If SW1 is VTP server and I am enabling a pruning on server, it does mean it
will enable in the entire VTP domain. SW2 and SW3 are clients in that VTP
domain.
Suppose SW1 has vlan 20 and I want to prune that vlan traffic to its
clients. Clients don't have any ports assigned to vlan 20.
I think the topology is pretty clear now.
So as the link is trunk carries all vlan traffic between SW2 and SW3. Does
VTP pruning will change anything by enabling on server (SW1)?
I think, it won't affect anything because both VTP clients have trunk ports.
In such lab scenarios, configuring VTP pruning eligibility list on server
trunks connected to other clients will be an idea to resolve this?
I am talking about *switchport trunk pruning vlan* command on SW1 trunk
links to SW2 and SW3.
I have no idea how can we enable pruning with such topology Please suggest.
Warm Regards,
Shahnawaz
Blogs and organic groups at http://www.ccie.net
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