I have a question about multihoming with 2 separate ISPs on 2 separate routers. Below is the layout of our data center and I?m currently in the planning phase of setting up the redundancy of our Internet connectivity. My question is this ? how does the redundancy work if the PIX only know how to route traffic to one default gateway. We will implement HSRP in case there is a hardware failure, but how does the routing work if the PIX isn?t running BGP? If the PIX has a static route that points to Router 1, how will Internet traffic flow through Router 2 in the case that ISP1?s backbone begins to have problems? HSRP won?t help in that case??
iBGP will be running between the two of my edge routers and they will use eBGP over to their respective ISP connections.
ISP 1 ISP 2
Router1 ==>iBGP <== Router2
PIX (525) PRIM - PIX (525) SEC
Internal Core (6500)
You can use HSRP object tracking on the outside routers and point the default route of PIX to the HSRP address. This way when the primary ISP tracked address becomes unavailable HSRP can decrement the penalty on Router1 and force Router2 to become the active router for the LAN and PIX would happily route all the traffic via Router2.