Cisco – Load balancing with multiple ISP, two routers and firewall

ciscocisco-asafailoverload balancingrouter

I have two ISP connections on two Cisco 2901 routers, in front of Cisco ASA-5515 firewall. I need to configure failover load balancing network.

  • Two Cisco 2901 router with dual (different ISP) connections.

  • One Cisco ASA 5515 firewall behind Cisco 2901 routers.

Please suggest me how to design the network, and then configure routers and firewall. A sample network diagram is attached below. I don't know if this is the correct way, please advise me.

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Best Answer

You could configure a floating static route. This is a method in which two default routes are configured one with a higher AD than the other so that when one link goes down the route would be removed and the backup inserted to take over. For this to work the 2901's would have to be plugged directly into the firewall to detect the link is down and therefor remove the primary route from the routing table.

route outside 0.0.0.0 0.0.0.0 192.168.1.1 1
route outsidebackup 0.0.0.0 0.0.0.0 192.168.2.1 2

P.S. In the question you say you use a 5505 and a 5515, which one is it? The only reason I ask is that the 5505 can have some limitations when it comes to named interfaces.

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