How much money you lost in an hour when your internet was down? How about internet down in a day, what would the impact to your business? Internet Multi-Homing is becoming an essential need for many companies now.
The simplest way to build your Internet Multi-Homing is with single router with dual power supplies connected to two different ISPs. It depends how big your network and your router type, you may able to get dual processors in one router. If you use two routers, you will need to configure the routers with HSRP, VRRP, or GLBP for connection to your switches.
How to configure the Internet Multi-home the simplest way? Use static routes with the floating static default routes set higher administrative distance as the backup internet path. This is an active-standby redundant internet connection. The primary route is used if the main connection is up, and the secondary route would come up only if the main connection is down. Static routing can only monitor an interface locally, and if the connection goes down indirectly upstream, it will not sense the loss of connectivity and cannot deactivate the route. You will need to configure with IP SLA to detect the loss of upstream routes on the primary ISP, so when indirectly upstream down, your traffic will flowing to the secondary ISP through the second router. You can use BGP if you want to have more flexibility to direct and load balance the traffic.
If you need help to design your redundancy network or verifying your network design and test it, please contact us.