VTP domain question

[stupman]

Hi there! Need some other opinions on this one.
Have 8 switches in total.
2 3750 stacked, fiber to other 3750.
To stacked 3750 3 C3550 are linked (trunks).
To other 3750 2 c2950 are linked.
Crossed links between 2 2950 and stacked C3750.
vice versa for 3550's.

Have VTP domain, only the stacked 3750 is VTP server, all others are clients. VLAN info spreading nicely. All is well.
My question in case of outage VTP server: should I make more VTP servers? The other 3750 is certainly up for the job, but is it abs necessary? When stacked 3750 is down, and others boot, what will happen? Will they go live without the precense of a vtp server??

Appreciate all your advise.

 

[lambent]

When stacked 3750 is down, and others boot, what will happen?

The switches will use their local VLAN database which was updated from the VTP server it goes down. So in theory there shouldn't be any problem in your multiple points of failure scenario.

However there are some caveats when you use VTP and you should be aware of them.

http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094c52.shtml#vtp_ts_cav

 

[Parcival21]

Hi there,
I'm not really sure if the following is right.
I heard that if you choose to have two VTP servers in your network only the messages of one of these servers will be accepted. So the other one could be a backup. I think it depends on some kind of timestamp which of the servers is chosen. But you should read about that.

Bye,
busche

 

[InDenial]

I could type a long explanation but why do that if someone else already did...;-)

vtp explained

there is a link one that page to

http://www.cisco.com

too for more info.

InDenial

 

[paulk29]

Guys,
in the case of 2 VTP Servers updates are multicast out to the network and the receiving switch compare the incoming Packet's ID number with the ID number of the last update stored in memory. If the incoming Packet's ID number is higher than the one in memory the switch overwrites memory with the latest VTP update.
So it doesnt really matter how many Servers you have a switch will always take the latest update.

Well this is how I understand it.

Paul Kilcoyne B eng. CCNA