Share VLAN Across Multiple Switches - Alternative to VTP?

[RichardParry]

Hi All,

I will be replacing a number of older 5000 and 2900 series switches shortly with a 6500 series (for the core) and 2950's. At present the 5000 is running as a VTP Server and the 2900's are trunked to the 5000, and run VTP in Transparent mode. This allows me to specify VLAN's that I want to use on specific ports across the trunk from the VTP Server on the 5000.

Works great, however since I am replacing all of this equipment with IOS derived (bar the 6500 which will run CatOS/IOS in hybrid mode) I was wondering if there is a better option to using VTP? I have not had a problem with this myself, however have heard horror stories that multiple VTP Servers on the network will cause headaches and that using different VTP versions can cause problems too (heard of some users having their entire VLAN list replaced by that of another VTP Server with a higher firmware revision).

Is there a suitable alternative to VTP, that will allow me to setup the VLAN's on the 6500 and distribute them over trunks to other switches as per with VTP?

Also, I would be looking at a second 6500 switch for redundancy shortly afterwards so wanted to check that the replacement solution I use to VTP will also be compatible with multiple 6500's.

Thanx! Richard

 

[jneiberger]

GVRP is that standard generic alternative to VTP, but I don't know much about it. I've never used it and I've never talked to anyone who has used it. You shouldn't have problems with multiple VTP servers on your network, though. In fact, depending on your topology and your goals, all of your switches could theoretically be VTP servers. However, you do have to be careful of the configuration revision number issue.

 

[vipergg]

Are any of your current 2900's in client mode ? If not then the server is really not doing anything and could also be run in transparent mode . If you want to run client/server mode then you should have 2 servers and the rest should be clients . The 2950's being a lower end switch are restricted to how many spanning tree instances they can support , it used to be like 64 instances of spanning can be supported . Running client /server is really not a problem if you understand how it works . The version issue is mitigated by just remembering that when you configure a new switch do a write erase on a IOS switch and then reload or a clear config all on a catos switch , this will reset the version number to 1 . Running client/server does save you the time and having to remember to create the layer2 vlan on each side of the link , it will be automatically propagated from the server switch down to all client switches within the same vtp domain . If for some reason you feel insecure about this then run everything in transparent mode , this does create extra vlan configuration on the switches .

 

[RichardParry]

Thank you for the replies. I have never had any success running in client/server mode. I always ran with the distribution switches in transparent mode, as I could never figure out how to assign VLAN's to specific ports this way, but could when in Transparent mode. Clearly I don't understand VTP properly, but whenever I would put a switch in Client mode it would never allow me to adjust the VLAN port assignments, so to me seemed rather useless - whereas Transparent mode worked great.

I might just give this another try, I had a spare 5500 and a 3500 series sitting here with a gigabit trunk between them for development/testing, so will have another read up on properly setting up VTP.

I thought however as VTP was mainly a CatOS derivitive, which is being phased out slowly with the introduction of the Sup720's that VTP would have been superceded with something newer?

 

[jneiberger]

It's simple:

Client: Receives VTP updates but cannot initiate VTP updates, which means you can't make VLAN changes on a client.

Transparent: Ignores VTP updates but does pass them on; you can make local VLAN changes.

Server: Sends and receives VTP updates.

It's easiest if you just set everything to server and be done with it.

 

[computerhighguy]

I agree. VTP is pretty darn reliable.

It is what it is!!
__________________________________
A+, Net+, I-Net+, Certified Web Master, MCP, MCSA, MCSE, CCNA, CCDA, and few others (I got bored one day)

 

[brianinms]

You should only have 1 or 2 servers and the rest should be clients. Typically I usually change the servers to transparent mode after I add my additional vlans.

 

[jneiberger]

I use to do the same (one or two servers and the rest clients) but I started doing all servers after a recommendation from Cisco engineers. It really did make life easier for me later. It doesn't really matter if you don't mind always having to go to the server to make vlan changes.

 

[RichardParry]

Okies, but if you're unable to create VLAN's on the distribution switches set to VTP Client mode, how do you assign a specific VLAN to a specific port, on the dist switches?

The only way I could do this was to set the dist switches to Transparent, then it would get the VLAN list from the server, and I could assign one of these VLAN's to a specific port.

Worked great that way, but never figured out how to get it to work in Client mode.

Thanx!

 

[jneiberger]

The VLAN needs to be created on a server. That VLAN will then be available on all client switches. If you just set them all to server to begin with, you can create new VLANs no matter what switch you're on.

 

[RichardParry]

That's what I was doing though, single VTP Server (Core switch), with VTP Client's (distribution switches). I would create the VLAN's on the server (core), and I could then setup the VLAN's, which would then propogate to the client switches, but how would I then assign specific VLAN's to specific ports, on the distribition (Client) switches?

 

[jneiberger]

You use the "set vlan" command on CatOS or use the "switch access vlan" command on IOS switches.

 

[vipergg]

To check to see if your setup is working correctly first they all must have the exact same vtp domain name . If all are working correctly they will all have the same config revision number also, "show vtp status on IOS or show vtp domain on catos boxes. . Do a show vlan to see if all server vlans have been propagated to the clients . The ports on the clients are then just set like you would any other port setup whether its a client/server setup or a transparent setup .

 

[johnilu]

Once working in Client/Server mode you will recieve VTP updates to the Client. Vlans are assigned to Switchports via the Switchport command in IOS and the set VLAN command in COS. The switchport access command is executed at the interface.

switchport access vlan XX

were xx is a vlan in the VTP data base.

 

[RichardParry]

Hmm, whenever I tried this before on CatOS switches (clients) it would always stop me - I can't remember what the error was without booting up a few test switches. This is why I had to use Transparent mode on the "client" switches.

I will give it another go on a 5000 as the server and a 3524 as the client and see what happens!

 

[jneiberger]

My guess is that you didn't have VTP setup correctly. The switches were in client mode but were not getting VTP updates. That would cause an error when you tried to assign a VLAN to a port since the VLAN doesn't exist. I bet you just had mismatched VTP domains or you had passwords configured (or misconfigured).

 

[johnilu]

I have had that specific operation working in our network with a 5000 class as server and the 3750 as client. You should be able to get it working. Make sure the vtp domain names are the same, and the passwords are correct.

Also the VTP revision number on the server is higher or the same as one on the client

Server COS

Feature Mode Revision
-------------- -------------- -----------
VLAN Server 276

Cliet IOS

VTP Version : 2
Configuration Revision : 276
Maximum VLANs supported locally : 1005
Number of existing VLANs : 32
VTP Operating Mode : Client
VTP Domain Name : XXXX
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Enabled