VALN locally assigned and VTP prunning and Domain

zillah

I have got this scenario like this

Switch1:
vtp domain DOGCAT
vtp password CISCO
vtp pruning
vlan 3,5,6,8,10,26,33,52


Switch2:
vtp domain DOGCAT
vtp mode client
vtp password



Requirement:

VLANs not locally assigned should not be received over any trunk links throughout the VTP domain.


Explanation:

By default, all VLANs are allowed to be sent over any trunk link in the VTP domain. Therefore, broadcast frames and frames destined for unknown unicast addresses will be sent over all trunks throughout the domain. This behavior is undesirable when one or more switches throughout the VTP domain receive traffic for VLANs that they do not have locally assigned and are not in the transit path for.

In order reduce this unnecessary traffic VTP offers a feature known as pruning.
VTP pruning allows a switch to communicate with its directly connected
neighbors about what VLANs they have locally assigned and are in the transit path for.

Therefore VLANs that are unnecessary can be “pruned” off of the
interface. VTP pruning can be enabled by issuing the vlan database or global
configuration command vtp pruning.



I am looking to understand the concept of boldface word,,,

1- Can we consider vlan (3,5,6,8,10,26,33,52) locally ? If so why do we consider them localy,,,do we consider them locally because we define them under vlan command ? or becaues they are in the same domain (DOGCAT) ?

2- ",,,, frames destined for unknown unicast addresses,,," ?!

3- " transit path for" ?

keenon

zillah wrote:

I have got this scenario like this

Switch1:
vtp domain DOGCAT
vtp password CISCO
vtp pruning
vlan 3,5,6,8,10,26,33,52


Switch2:
vtp domain DOGCAT
vtp mode client
vtp password



Requirement:

VLANs not locally assigned should not be received over any trunk links throughout the VTP domain.


Explanation:

By default, all VLANs are allowed to be sent over any trunk link in the VTP domain. Therefore, broadcast frames and frames destined for unknown unicast addresses will be sent over all trunks throughout the domain. This behavior is undesirable when one or more switches throughout the VTP domain receive traffic for VLANs that they do not have locally assigned and are not in the transit path for.

In order reduce this unnecessary traffic VTP offers a feature known as pruning.
VTP pruning allows a switch to communicate with its directly connected
neighbors about what VLANs they have locally assigned and are in the transit path for.

Therefore VLANs that are unnecessary can be “pruned” off of the
interface. VTP pruning can be enabled by issuing the vlan database or global
configuration command vtp pruning.



I am looking to understand the concept of boldface word,,,

1- Can we consider vlan (3,5,6,8,10,26,33,52) locally ? If so why do we consider them localy,,,do we consider them locally because we define them under vlan command ? or becaues they are in the same domain (DOGCAT) ?

2- ",,,, frames destined for unknown unicast addresses,,," ?!

3- " transit path for" ?

where did this come from?

well i can tell you this much switch 1 is either server or transparent.. but being it mentions locally i would say that its in transparent mode which mean its not going to pass its locally created vlans regardless of the domain.

if its vtp server(which i do doubt) switch 2 won't receive vtp info anyway due to the vtp password ( i have seen this a few times when troubleshooting other peoples network)

the parts in bold, it sounds like it wants the transparent vtp switch to prune vlans off that are being sent by the vtp server to the clients..

Ten9t6

All the scenario is asking you to do is to not send traffic where it does not need to go.


The first switch is the VTP server...you have assigned the domain name and password. The second is set up as a client, which will receive the vlan information from the server......if you put the same password on it.

In this scenario, you enable VTP pruning on the server and it affects all the switches in the domain.

Here is what that does: You have assigned vlans 3,5,6,8,10,26,33,52 to the server....which in return is passed to the clients. If I have a trunk hanging off one of the devices that only has vlans 3,5,6 on it.....There is no need for traffic looking for a device on the other vlans to cross the trunk. This cuts down on a lot of traffic.

In a LAN, if I need to get to a device and I do not know where it is, I will send out a broadcast looking for it. This is the same in a VLAN. It will flood this out all ports / trunks that are part of the vlan in question. So, if no ports are assigned to that vlan, why send the traffic that direction? That is what pruning does.

Does this make sense...or am I just rambling..?

Kenny

zillah

Thanks Kenny, please comment this also

1- Can we consider vlan (3,5,6,8,10,26,33,52) locally ? If so why do we consider them localy,,,do we consider them locally because we define them under vlan command in gloabl configuration ? or becaues they are in the same domain (DOGCAT) ?