VTP Issue

[NetworkGoats]

I have a topology with a couple switches separated by a few routers, working within a practice lab in Web-UI of GNS3.

On both switches, I configured the interfaces leading to the routers as trunk ports using dot1Q encapsulation. I also set both to the same VTP domain with caps in mind, no VTP password, and both running VTP version 2.

Both are configured as servers still, but if you create a VLAN on either one and type exit, it will not show up on the other switch. Show VTP Status shows the revision numbers do match up. I know I'm missing something simple.

I have 2 PCs hanging off of the switches that are able to ping each other since they are still in VLAN1, so I know the connectivity is good.

[NetworkGoats]

Thank you everyone for the replies. I didn't realize you needed a special switching module in routers to accomplish this.

In the real world, how are VLANS created in an organization with several branches in different cities? I assume VTP is not used as they don't want to install switching modules in all the routers in between?

Is some form of automation used more or less instead, pushing all the VLAN creations and configurations via some other method?

[TJ-20933766 · Accepted solution]

In most of my installs, we don't use VTP because there is the possibility of adding an old switch that doesn't have all the VLANs that are currently in use. Adding that switch to the environment without first having wiped the config may result in over writing the VLAN database for the whole campus causing a massive outage. Cisco even recommends not using VTP.

As for your question about VLANs in an organization with several branches in different cities, I use the same VLAN number at all the locations but they are not directly connected via Layer 2. So even though Site A has VLAN 10 and Site B also has VLAN 10, they are different subnets because I am routing the network.

[NetworkGoats]

Thanks Tyson for that information. I was able to successfully configure it pretty quickly on just the LAN side, so that's as far as I'll go with labbing with VTP. I just saw it on the CCNA blueprint and wanted to mess around with it. I'm not studying for it but more so just learning things on my own. I really appreciate the real world scenario!

[Georg Pauwen]

Hello,

on a side note, there is VTP version 3 now, which features the VTP primary server, the only one able to create / modify / delete VLANs. That eliminates the problem of “accidently” wiping all VLANs due to a higher revision number, like you could with VTP version 1 or 2.

[paul driver]

Hello
Glad to hear you are studying and reviewing the protocol for real use, You will find very quickly how things work in a real environment.
Server /client modes can and will overwrite the vtp database of any vtp domain if the revision numbers are higher than the current  vtp revision number running on the network

So whenever i introduce a switch be it new or used I always delete the config.text and vlan.dat file from the flash and before i actually introduce it to the production for a final time change the vtp mode from transparent back to either server or client modes or even off.

Lastly If you are thinking of introducing vtp 3 please note its ONLY compatible with ver 2 which isn't compatible with vtp ver 1, So you need to either to vtp ver 2 throughout your estate beforehand or youll need to upgrade from ver1 to ver 2 before version 3.

[NetworkGoats]

Great information, thank you Paul!