I have a gigabit MAN connection between two buildings that acts like an ethernet bridge. Connected to each end of this gigaman are Catalyst3750's. Hanging off the catalysts are a primary Host (AS/400) and a "High Availability" host which journals off the primary (one host at each physical location). With the MAN connection, these hosts appear on the same ethernet segment, so we can swap a virtual IP between the two hosts, making rollovers very easy.
Also connected to each catalyst is a checkpoint firewall which serves as the gateway device to the rest of our networks and the Internet.
So, simplified ascii connection diagram (not sure if this helps):[LAN1][Firewall1][3750 #1][3750 #2][Firewall 2][LAN2]
Host1 is connected to 3750 #1, and host2 is connected to 3750#2.
The default gateway of the each host is currently the interface on FW1. Which works great for LAN1, but breaks for LAN2. Explanation:
Syn packet comes from LAN2 destined for host1, is evaluated by FW2 which allows the connection to host1. The Syn-Ack for lan2 is sent out the default gateway, which is FW1. FW1 never saw the initial syn, so drops the connection as "out of state".
In the current situation, the problem is easily solved by putting static routes to LAN2 on each of the hosts.
However, now, we want to add some redundant WAN links to both facilities. Preferably with automatic failover using a routing protocol (probably OSPF). This means the static routes on the hosts are no longer sufficient.
The hosts don't run OSPF, though they can run RIPv2 and we could redistribute the routes.
Alternatively, we believe we could put two routers next to the hosts that participate in the OSPF area and run HSRP to share an IP. That VIP could be the default gateway for the hosts. Then, the syn-ack will go to one of those routers which will forward it along to the appropriate firewall.
So then we go one step further, and realize those are multilayer switches. Can we have both switches run OSPF and still use HSRP?
Is this possible? Can you think of a better solution?