There is a fundamental problem in the design of this network and to fix it the original poster will need to implement a different design. The problem is fundamentally that this is an attempt to have the same layer 2 vlan in two different places connected by a layer 3 connection. And that does not work.
Perhaps the simple way to illustrate the problem is to think of a PC connected to the vlan on router 1. Perhaps it has IP address of 192.168.1.50. And it wants to communicate with a PC connected to the vlan on router 2 and perhaps this PC has IP address of 192.168.1.150. For them to communicate PC 1 must ARP for PC 2. But the ARP is a broadcast packet and router 1 does not forward a broadcast from a vlan over the serial interface. So PC 2 never receives the ARP from PC 1 and they can not communicate.
The easy solution to this problem is to make the IP subnets different on each side of the serial connection. Perhaps Router 1 could have networks 192.168.1.0 and 192.168.2.0 while router 2 has networks 192.168.11.0 and 192.168.12.0.
If the original poster really needs the same vlan on both sides of the serial connection then he needs to implement a technology like l2tpv3 which does provide the ability to connect a layer 2 network accross a layer 3 connection. See this link for some information about this
http://en.wikipedia.org/wiki/L2TPv3
HTH
Rick
HTH
Rick
