Default routes in BGP

By | March 19, 2019

There are 3 ways of advertising default route in BGP.

Method 1: Using network 0.0.0.0 command.
It requires only that the route 0.0.0.0 is present in the Interior Gateway Protocol (IGP) routing table. This is the preferred approach.

Method 2: Using default-information originate command.
It requires explicit redistribution of the route 0.0.0.0. This protects against someone accidentally redistributing a default route in BGP which could potentially be disastrous.

Method 3: Using neighbor default-originate command.
This method does not require the presence of the 0.0.0.0/0 network in the routing table of the advertising router.

https://community.cisco.com/t5/routing/bgp-default-information-originate/td-p/772779

http://lostintransit.se/2013/06/12/default-routes-in-bgp/

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