RSS

BGP Backdoor Route

Share this page:

When you need to prefer LESS the eBGP route - you need a way to tune it, because not many routing protocols “beat” the eBGPs Administrative Distance (20). The “backdoor” argument sets the routes AD to 200 (like it were an iBGP instead of eBGP route), and alters the order of preference in the routing table.

It’s quite easy to configure - you configure a regular network using a “network” command, but add a “backdoor” argument at the end.
*BE CAREFUL!!! The BACKDOOR argument is applied to the network advertised TO YOU, not from you like in the normal “network” command application

**(config-router)#network 150.1.3.0 mask 255.255.255.0 backdoor **

Note that you will not SEE this route in the routing table unless the route with the bigger AD is down.