CentOS Network Failover

[DardanIsufi95]

Hello guys I'm pretty new to CentOS (Linux) , I have a problem that i need help with :
I have , a server with 5 NICs running CentOS 7 as a VM on Citrix Hypervisor , connected on NIC1 is ISP1's (with a static IP ) media convertor , on NIC1 is ISP2's (with a static IP ) media convertor.

So I need to configure a dual WAN router with DHCP runing on CentOS , where ISP1 should be the primary WAN connection and ISP2 the the backup plan if there is no internet connection on ISP1, as for DNS I intend on using google , NIC3-5 should be the LAN connections , the internal IP's distributed should stay the same in case of a WAN swap.

What would be the best approach to accomplish this , any help is appreciated , if you need any further information plz ask them

[felschmidt]

Hi,

my prosal is to set the default route with a lower metric to your primary isp and one with an higher metric to your second isp. So primary the route with the lower metric will be used and then your primary isp goes down. The second will be used.