Transparent VTP Mode

I understand transparent mode only forwards VTP advertisements and saves vlan info only to its local config (without syncronizing).. What I am wondering is if the vlan information database is saved to run config, NVRAM, or both?

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Comments

zero-g-smith

according to the latest ICND a client mode switch does not save the vlan config at all. It says it cannot save vlan info in nvram.

tuscani

I am not referring to client mode.

hectorjhrdz

cisco says:

Guidelines

•Before you can create a VLAN, the Catalyst 6500 series switch must be in VTP server mode or VTP transparent mode. For information on configuring VTP, see "Configuring VTP"

•The VLAN configuration is stored in the vlan.dat file which is stored in nonvolatile memory. You can cause inconsistency in the VLAN database if you manually delete the vlan.dat file. If you want to modify the VLAN configuration or VTP, use the commands described in this guide and in the Catalyst 6500 Series Switch Cisco IOS Command Reference publication.

good luck

pr3d4t0r

zero-g-smith wrote:

according to the latest ICND a client mode switch does not save the vlan config at all. It says it cannot save vlan info in nvram.

According to cisco :

Transparent—VTP transparent network devices do not participate in VTP. A VTP transparent network device does not advertise its VLAN configuration and does not synchronize its VLAN configuration based on received advertisements. However, in VTP version 2, transparent network devices do forward VTP advertisements that they receive on their trunking LAN interfaces. VTP transparent is the default mode.

The vlan.dat file should treat with care.

rakem

VTP Transparent mode saves the config to NVRAM.

mzinz

I'm very confused about this as well.

From what I've read online from my Cisco Academy pages.. the modes do the following:

Server:
Create, Add, Delete, etc.
Forward VTP messages out all trunk ports.
Process and add incoming VTP messages, saving them to NVRAM.

Client:
Process changes received from VTP messages.
Forward VTP messages. (To NVRAM.. im guessing?)

Transparent (the confusing one):
Forward VTP messages.
CISCO: "Except for forwarding VTP advertisements, VTP is disabled on a transparent switch."
...It also mentioned, in more detail, that transparent switches do NOT process incoming VTP messages, and they do NOT advertise changes which occur on their own switch. So other than forwarding messages from other switches, they do NOT participate.

Hope that clears things up!

david_r

justindu,
My switch stores the vlan.dat file in flash and it responds with "APPLY comleted" when I exit vlan database which means it is writing the file. It must also store it in RAM as all the vlan info is there after I delete the vlan.dat file.

What I'd like to know is where it stores the info that it is set to client mode?

Obliged

david_r wrote:

What I'd like to know is where it stores the info that it is set to client mode?

If I understand your question correctly, Server and Tranparent mode (not Client) actually store the data in NVRAM. Client mode processes it.

david_r

Obliged,
I get that -- in the vlan.dat file (or whatever we want to name it). What I don't get is there are (at least) 2 bits somewhere that tell a router it is Server, Transparent or Client. Where are these bits? If you delete the vlan.dat file, access the vlan database in client mode and exit, the router doesn't not create a vlan.dat file like it does in server or transparent. But when it reboots, it knows it is a client. For that matter, it knows what VTP domain it is a member of. Where is this info kept?

EdTheLad

david_r wrote:

Obliged,
I get that -- in the vlan.dat file (or whatever we want to name it). What I don't get is there are (at least) 2 bits somewhere that tell a router it is Server, Transparent or Client. Where are these bits? If you delete the vlan.dat file, access the vlan database in client mode and exit, the router doesn't not create a vlan.dat file like it does in server or transparent. But when it reboots, it knows it is a client. For that matter, it knows what VTP domain it is a member of. Where is this info kept?

Wow,lots of fuss over vtp,heres my input,hope it helps!

By default a switch is a server,by default a switch has no vlan.dat.Once you modify vtp with a domain name or vlan id the switch creates the vlan.dat file.All vlan info is stored in this file and on startup the switch reads from this file to configure the various vlans and domain etc.

If a switch is a server and you have not modified any vtp paramters it will not have a vlan.dat, if you now change the mode to client it still will not have a vlan.dat file,as soon as a vtp update is received by the client,the client will create a vlan.dat and store the info there.On reboot the client will reload the config from the vlan.dat file.No vlan configuration is possible on the client and the vlan.dat can only be updated by the server.

If a switch is a server and you have not modified any vtp paramters it will not have a vlan.dat, if you now change the mode to transparent it will create a vlan.dat.In transparent mode you can modify the vlan.dat loaclly i.e. create,delete vlans etc, in transparent mode it will just forward vtp updates received to other clients and servers without modifying its vlan.dat file.