BGP Redundant Links

[Drew Browning]

I want to setup the network that I attached in a way that ALL internet traffic uses the BGP connection of ISP 1 unless it becomes unavailable then i want all traffic to flow to ISP 2.  Can I use Conditional BGP Routing or is there an easier way?

[daniel.dib · Accepted solution]

For outbound it's easy. Run iBGP between R1 and R2. Set local preference on prefixes coming ISP1 or which one is preferred. R2 will then go through R1 to exit the network.

For inbound it is a bit more complex, you can try to prepend on the secondary or preferably check if your ISP supports communties and tag the routes with communities. The ISP will then prepend for you or set a lower local preference in their network.

There is no fool proof way though of always getting traffic in via R1. What's the background for using this setup?

Daniel Dib
CCIE #37149