Cisco vtp not updating
The configuration of a VLAN includes the VLAN number, name and a few more parameters which will be analysed further on.This information is then stored on each switch's NVRAM and any VLAN changes made to any switch must again be replicated manually on all switches.Any change in the VLAN database will trigger an update from the VTP Server towards all VTP clients so they can update their database.Lastly, be informed that these VTP updates will only traverse Trunk links.
Below you'll find the 3 modes the VTP protocol can operate on any switch throughout the network: Each mode has been designed to cover specific network setups and needs, as we are about to see, but for now, we need to understand the purpose of each mode and the following network diagram will help us do exactly that.
If you're responsible for a network of up to 4-6 switches that include a few VLANs, then you'll surely agree that it's usually a low overhead to administer them and periodically make changes - most engineers can live with that:) Ask now an engineer who's in charge of a medium to a large scale network and you will definately not receive the same answer, simply because these small changes can quickly become a nightmare and if you add the possibility of human error, then the result could be network outages and possibly downtime.
VTP, a Cisco proprietary protocol, was designed by Cisco with the network engineer and administrator in mind, reducing the administration overhead and the possibility of error as described above in any switched network environment.
This means that you must ensure that all switches connect to the network backbone via Trunk links, otherwise no VTP updates will get to your switches.
Let's now take a closer look at what each VTP mode does and where it can be used.