From: kwasi-ccie@comcast.net
Date: Sun Aug 13 2006 - 01:06:25 ART
Basically to summarize:
By default when vtp pruning is NOT configured, the server will send to the receiver (a client or server) all vlans that it knows of and falls within trunk allowed list (1 - 4094, I believe).
By default when vtp pruining is enabled on the server, the server will only send to the receiver the vlans that the receiver has requested for (in its own vtp updates). The receiver's vtp updates essentially is a request to the server for vlans that are locally configured on the receiver or originated from a downstream switch.
Only the native vlan 1 and vlans >1002 are by default NOT prune eligible. Vlans 2-1001 can be prune.
Since vlan 8 is prune eligible, for the sever to send vlan 8 to the receiver (even though is NOT locally configured on the receiver or on a downstream switch), the server has to remove vlan 8 from the prune eligible list.
"switchport trunk pruning vlan remove" affects the what vlans the server will send to the downstream swicth.
"switchport trunk allowed vlan remove" affect what vlans the local switch will allow on its port.
-------------- Original message --------------
From: Tim Chan <timanji@yahoo.com>
> I think what helped me understand was this...
>
> Globally you enable vtp pruning. But per interface you can
> define what vlans are eligible to be pruned. (Which is what Kwasi was saying..)
>
> So in my original example Fast0/13 - 15 are trunked. But only Fast0/13
> is not allowing vlan 8 to be pruned. Thereby taking care of task 2.
>
> vtp pruning
> !
> interface fast0/13
> switchport trunk encapsulation dot1q
> switchport trunk pruning vlan 2-7,9-1001
> switchport mode trunk
> !
> interface fast0/13
> switchport trunk encapsulation dot1q
> switchport mode trunk
> !
> interface fast0/13
> switchport trunk encapsulation dot1q
> switchport mode trunk
>
> S1#sho int fast0/13 switchport
>
> Trunking VLANs Enabled: ALL
> Pruning VLANs Enabled: 2-7,9-1001
>
> S1#sho int fast0/14 switchport
>
> Trunking VLANs Enabled: ALL
> Pruning VLANs Enabled: 2-1001
>
> S1#sho int fast0/15 switchport
>
> Trunking VLANs Enabled: ALL
> Pruning VLANs Enabled: 2-1001
>
> hope this helps,
> -tim
>
> ----- Original Message ----
> From: Godswill Oletu
> To: kwasi-ccie@comcast.net; Tim Chan ; ccielab@groupstudy.com
> Sent: Saturday, August 12, 2006 7:46:23 AM
> Subject: Re: trunk allowed vs pruning
>
> Kwasi,
>
> Except I am missing something, I do not see how VTP pruning will always solve
> the second problem, to my understanding the second problem states that:
>
> >traffic for vlan 8 should not be received over any of the other trunk
> > links
>
> When VTP pruning is enable on a switch, the switch is simply saying, "....I
> will not receive VLAN traffics through any trunk interface for any pruning
> eligible VLANs that are not locally assigned".
>
> For pruning eligible VLANs, VTP pruning dynamically turned ON or OFF the
> reception of specific VLAN traffics depending on the existence of that VLAN in
> the receiving switch.
>
> The only time when VTP pruning will be sufficient for the above task is when
> VLAN 8 is not locally assigned/configured on SW1.And if VLAN 8 is not
> configured on SW1 today, the mention of VLAN 8 might be a prelude to its
> addition in the future and one will want his/her solution to also address that
> situation.
>
> It is very important that one's understanding & application of these
> technologies is not limited to how it is applied in a particular vendor's
> workbook. How one interprets Words like NOT, NEVER, MAY, ALWAYS, etc goes a
> long way in determining the out come of the Lab exam.
>
> Since VTP Pruning is a dynamic process which rely on the existence of a
> locally assigned VLAN, it might not be a good idea to depend on it as a
> solution for a task that states that a particular VLAN should NOT be received
> over a trunk port.
>
> It is always good to nail down one's solutions, do not leave anything to
> chances. More so because one do not know how the proctor will test to see if a
> particular task was given the appropriate solution. e.g. One valid proctor test
> for the above task might be to configured VLAN 8 on SW1; if that is the case,
> then only enabling VTP pruning and not editing the VLAN Allowed list might not
> be the correct solution.
>
>
>
> HTH
>
> Godswill Oletu
> CCIE #16464
>
>
> ----- Original Message -----
> From: kwasi-ccie@comcast.net
> To: Godswill Oletu ; Tim Chan ; ccielab@groupstudy.com
> Sent: Friday, August 11, 2006 1:42 PM
> Subject: Re: trunk allowed vs pruning
>
>
> You only need to remove vlan 8 from the prune eligible list on sw1 port
> fa0/13 to solve problem 1 (switchport trunk pruning vlan remove 8). Problem
> 2 is already solved by the vtp pruning that you enbaled on both switches.
> You do not need to play with the vtp allowed list to solve these 2 problems.
> Test it out.
>
>
> -------------- Original message --------------
> From: Godswill Oletu
>
> > Tim,
> >
> > The solution you provided will only take care of the first task, once
> VLAN 8
> > is removed from the prunning eligible list of interface fa0/13, the
> switch
> > will continue to receive traffic for VLAN 8 regardless of local
> assignment
> > or not.
> >
> > For the second task, you have to remove VLAN 8 from the VLAN allowed list
> on
> > interfaces fa0/14 & fa0/15.
> >
> > HTH
> >
> > Godswill Oletu
> > CCIE #16464
> >
> >
> > ----- Original Message -----
> > From: "Tim Chan"
> > To:
> > Sent: Friday, August 11, 2006 2:21 AM
> > Subject: trunk allowed vs pruning
> >
> >
> > > Hi all,
> > >
> > > I keep confusing myself and need some clarification.
> > >
> > > What's the relationship between "vtp pruning" and "switchport trunk
> > allowed"?
> > >
> > > In one of the workbook labs, one of the tasks states:
> > > 1. although it does not have it locally assigned ensure that SW1
> receives
> > traffic for vlan 8 over Fast0/13
> > > 2. traffic for vlan 8 should not be received over any of the other
> trunk
> > links.
> > >
> > > (The two switches are trunked together on Fast0/13-15 using dot1q.)
> > >
> > > So my thinking is to do "switchport trunk allowed vlan 8" on fast0/13
> and
> > to not allow it on 14 & 15.
> > >
> > > But the solution says the answer is "switchport trunk pruning vlan
> > 2-7,9-1001".
> > >
> > > How does this solution solve either of the two tasks?
> > >
> > > Please advise,
> > > -tim
> > >
> &g t; >
> _______________________________________________________________________
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