We have a single public /24 subnet, with a BGP router as the primary gateway. Now I'm interested in configuring a second router for redundancy.
How do I deal with multiple gateways on the servers in our public subnet?
I found some other questions related to multiple gateways that seem to deal with NAT set-ups. In my situation, the servers all have public routed IP-addresses. So from what I can tell, it doesn't really matter which route incoming or outgoing packets take.
But I figure the servers need some way of telling when one of the gateways is down, and route around it? Is this accomplished with protocols such as OSPF? And do I need to deploy this on all my servers?
You want to look into HSRP and tracking. It depends how you will define 'gateway is down' - look into http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094e8c.shtml.
Or, if you have 2 routers and they're running BGP, just use HSRP between them, and if router 1 loses its link to the internet (BGP goes down), if it is the active HSRP router, it will just send all the packets to router 2 because it doesn't have a better route.