VLANs & VTP

Christopher Dobkowski

Hi to everyone!

I just finished the VLANs and VTP chapter and have some questions I need answers to leave this chapter with no weight on my chest

1. Client VTP switches can't have VLANs on their interfaces that Server VTP switches don't have on their interfaces. Because Client switches can't create VLANs. So if Server switch has VLANs 10, 20, 30 on it's interfaces, then a Clients of this VTP can't have a VLAN 40 on any of it's interfaces, only 10, 20 and 30. In order to create a VLAN 40 on the client switch I will need to set it to server. [Correct/False(why?)]

2. Does a VTP server switch have to be directly connected to a router? Or it can just be one of the 7 switches and a client VTP is connecting to the Router in order to terminate the network? [Yes/No(why?)]

Thank You in advance!

Dan-Humphreys

1. Correct. The reason for this is, goes back on to what you said yourself. The VTP server will proporgate the VLAN's to all clients, I think of it as using VTP as a management system. I personally would prefer to predefine all VLAN's on one switch (the server) and let it communicate this information to all other switch's under the same administration (Clients) If for instance you wanted to add VLAN 40 to just one switch and also have 10, 20 and 30 on it you would have to configure it as 'transparent' and configure it with all VLAN's. If I haven't explined it completely please ask.

2. No I don't believe the VTP server has to be directly connected to a router as switch's that are locally connected do not need a router to route information between them. I imagen from VTP's point of view, a router would be on the 'outside' so to speak.

Christopher Dobkowski

Mhmm, oooohhhh ok, even if your switch is set as transparent and it has the vlan 10, 20 and 30 on it, the users on that switch (transparent) still will communicate with other users on those VLANs on other switches regardless if they are part of VTP or not r8?

oli356

It doesn't matter if the switch is in transparent mode and others are in server/client. Transparent switches can communicate with the other switches fine.

All vtp does is share the VLANs across the trunk ports. So a network administration wouldn't have to go and create that vlan on every switch for example.

Christopher Dobkowski

But still, you will have to assign the ports to the corresponding VLANs, what VTP simply does, is using the "vlan #" command under the hood just so you don't have to type this command for all 40 VLANs you have, unless you use dynamic VLANs governed by a MAC table associated with VLANs (running VMPS) which goes something along the ways of: "If the MAC Z-Z-Z connect's to any of my unassigned ports, I (switch) will automatically turn that port to VLAN X, cause that's what my administrator told me."

Correct?

Mrock4

Correct, think of VTP as an administrative time-saver. If you have three devices such as:

SW1

---

SW2

---

SW3

And you have VTP server/client mode on SW1 and SW2...host A on VLAN 10 off of SW1 can still communicate with host B on VLAN 10 off SW3..as long as the VLAN is A) configured on SW3 (and assigned to the proper port for host , and allowed/trunked across the interswitch links.