Upgrading WAN from Point-to-Point T1s to AT&T Ethernet Services

I am finally upgrading 6 buildings to fiber and decided with the any-to-any configuration. I just received an email regarding Vlan IDs for each building.

Currently the T1s are configured on serial interfaces on Cisco router and their IPs are on a different subnet compared to the LANs subnet for that particular building.

i.e. Building #1 - LAN is and the serial Int is and for each end of the T1.

Should I keep this type of reasoning for the fiber?

I.e Building #1 - LAN is and the Fiber VLAN ID is 9

AT& T wants a list of VLAN IDs but i want to  make sure i am setting this up correctly.
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Don JohnstonInstructorCommented:
They would only need VLAN ID's if you're going to be using the service as a layer-2 service.

Since your current model is with the WAN links as a layer-3 service, I would stick with that.

Which means, as far as AT&T is concerned, VLANs are irrelevant.  Just tell them you'll have a router at each location.
csltAuthor Commented:
They still wanted vlans.

So this is what I was thinking.

using GE0/2 on the Cisco 3945

Router_A(config)#interface gigabitethernet 0/2
Router_A(config-if)#no shutdown
Router_A(config-if)#interface gigabitethernet 0/2.1
Router_A(config-subif)#encapsulation dot1q 5
Router_A(config-subif)#ip address
Router_A(config-if)#interface gigabitethernet 0/2.2
Router_A(config-subif)#encapsulation dot1q 7
Router_A(config-subif)#ip address
Router_A(config-if)#interface gigabitethernet 0/2.3
Router_A(config-subif)#encapsulation dot1q 9
Router_A(config-subif)#ip address

I would continue this for the remaining buildings?
Don JohnstonInstructorCommented:
What device does this new fiber terminate on?  If it's a router, I don't understand the purpose of defining multiple VLANs on that link.

Are the new links running from a central site to each remote site?  Or is it a LAN service where each site can communicate with all other sites directly?
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csltAuthor Commented:
LAN service - Multipoint

New Fiber terminates on a Ciena 3930 Switch with optical hand-off.

Dont know why either; just confused now.
Don JohnstonInstructorCommented:
So all the VLANs are being carried on the new multipoint fiber links.  

Is the 3930 switch performing the interVLAN routing?  Or is that the job of the Cisco router?

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csltAuthor Commented:
I just emailed the PM for the project and questioned why i need to use vlans and now they are siding with me. So i have a conference call with their engineer to tell them i would like to use my routers, not switches, for this multipoint setup.
csltAuthor Commented:
The 3930 switch was provided by AT&T and i have requested a copy of their config and have not received anything. But since i was a granted a new meeting with one of their engineers; I will requesting them to change the setup so I can utilize my Cisco routers.
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