Dual 6506 IOS switches in each of two buildings (A1,A2,B1,B2). Dual 3750 IOS switches in each of two other buildings (C1,C2, D1,D2). Each building pairs are will run HSRP to the LAN segments. Each pair is also tied to another building pair for MAN redundancy (ie. A1 ties to B1 and C1, A2 ties to B2 and C2, B1 also ties to D1, B2 also ties to D2; if A1B1 link goes down A2B2 will take over). Need to provide a VLAN or two that spans the 4 locations for layer 2 needs such as maintaining server cluster heartbeats between servers dispersed between buildings. Need to maintain MAN redundancy between buildings and route traffic from one building's LANs to another. What's the best way to handle this?
I have this problem too.