Wan routing with vlns

[nolan.dorsett]

Can anyone help me with this. What i have is 4 cisco 3550 connected together and each 3550 has a dumb switch and a few pc's connected to it. I need to know how to properly setup vlans and trunking, please send configurations step by step from the 3550 down to the pcs. I really need some help? a diagram is attached. Use it as a guide line be as detailed as possible

[jheckart]

You only need to tag the traffic on the switch and sub-interface's.

If you have VLAN2 and VLAN3, you'll need the following:

3550

Fa0/1

switchport access vlan 2

switchport mode access

Fa0/2

switchport access vlan 3

switchport mode access

Fa0/24

switchport mode trunk

switchport trunk encapsulation dot1q

Router

int fa0/1

no ip addr

int fa0/1.2

encapsulation dot1q 2

ip addr 192.168.2.1 255.255.255.0

int fa0/1.3

encapsulation dot1q 3

ip addr 192.168.3.1 255.255.255.0

The VLAN is only within each site. Once the traffic gets routed, it no longer needs to be tagged. Think about having a native VLAN, which is 1 by default. Everything else that would traverse the LAN must be tagged.

Nothing at all on these links would be tagged. These links between sites are layer 3. You're not tagging at layer 3.

[nolan.dorsett]

Ok but the link from router to router jsut set subinterfaces on them put them in the same subnet and thats it i dont need to put then in a vlan or trunk these links

[jheckart]

It depends on the technology. If you're just using point-point T1's or something, you'll use no sub interfaces between routers, and there will be no tagging between routers. It would just be a layer 3 routing decision between routers.

If you're doing frame-relay, you can use sub-interfaces, but you're still not tagging with VLAN's.

To put it simply, if you could tag your traffic with VLAN id's across the WAN, you wouldn't have to have routers (assuming that the service provider gave you an ethernet handoff).

[nolan.dorsett]

In response to your last answer we have to do this using wireless links. picture a point to point connection between each router using wireless antennas will i need trunking, tagging, or anything and the router are layer 2 first then layer three which means everything has to be done on the vlan. So would any ports need to be tagged or trunked in this case or put in vlans. The only way for me to put an ip address on the interface of these routers is with vlans

[jheckart]

You would still have a routed link between two routers. You're not going to be tagging traffic between them.

[nolan.dorsett]

But the links between router obviously will be on a vlan to put an ip address on them i assume both ends of the link will be in the same vlan, same subnet, can i just apply a vlan to the port and put an ip address on it or can i use subinterfaces with vlans attached to them. Please be detailed hopefully this is it. So i dont have to trunk these ports that link from router to router considering that data from each company is going to be trafficing these from each vlan i just need subinterfaces is any of this correct.

[jheckart]

I think I am just missing something in your design...

If you look at the basics of two routers connecting to a switch in the same vlan, there are two ways.

1 -

Router1-Fa1/0->Fa0/2-Switch-Fa0/2<-Fa2/0-Router2

Router1 - No tagging/sub-interfaces

Router2 - No tagging/sub-interfaces

Switch Fa0/2 - switchport mode access, switchport access vlan 10

Switch Fa0/1 - switchport mode access, switchport access vlan 10

2 -

Router1-Fa1/0->Fa0/2-Switch-Fa0/2<-Fa2/0-Router2

Router1 - Encapsulation dot1q 10, sub-interface fa1/0.10

Router2 - Encapsulation dot1q 10, sub-interface fa2/0.10

Switch Fa0/2 - switchport mode trunk, switchport trunk encapsulation dot1q

Switch Fa0/1 - switchport mode trunk, switchport trunk encapsulation dot1q

Scenario 1 has no requirement of tagging by the routers. Scenario 2 requires tagging due to the fact that the router links are trunks.

If you take the switch out of the equation and have...

Router1-Fa1/0-><-Fa2/0-Router2

In this case, I don't know why you'd want this link to do anything but route.

Unless your project has another requirement, use sub-interfaces only within the site, and p2p links between sites. Each site will be able to get to each VLAN whether it is inter or intrasite providing that a route is present on the router.