Local Subnet to Edge Router two networks

[pain112]

Hello,

I need your help as we make some changes on our network.

We currently have two sites 150 miles apart we join both by way of fiber and on each side we have Cisco 3750 stack switches, configure trunking for all Vlans on one port in site one then through the the long haul fiber to site two with site one using 10.1.1.30 and site two using 10.1.1.40 as their default gateway, with static routing allVlan subnets to the other sites default gateway life is good.

My question - seeing how we have sites using the same subnet 10.1.1.x to trunk all data to each site through switches; we need to now change the network and add each site to the MPLS network, site one switch 1 IP address 10.1.1.30 going to MPLS router one with FA0/0/0 using IP 10.1.1.31, site two having switch 1 IP address 10.1.1.40 going to MPLS router one with FA0/0/0 using 10.1.1.41. I need to know will this work.

We have the same subnet in each site 10.1.1.x to the MPLS routers then the external router interface connecting each site to local switches, will this cause any problems by using the same local subnet for each site?

Thank you

Stephen Sisson

pain112@msn.com

[Reza Sharifi]

Hi,

Since both sites are in one layer-2 domain, you don't need to assign IP address an each site to connect to your provider (10.1.1.31 and 10.1.1.41).  The provider will take the vlan on one site, tag it and send it across their layer-3 MPLS.  In the other site, they will hand off the same vlan to you.  The layer-3 MPLS would be transparent to you.

HTH