Route Redistribution

Redistribution is the process of inserting routes from one protocol into another. This allows the dynamic installation of routes into the BGP routing table. This allows the routing process internally and externally to become totally dynamic. While this can be beneficial, reducing the ammount of administrative overhead installing routes, this can create other problems, such as routing loops.

Routes redistributed into BGP are always labled with an origin type of 'incomplete' because they were inserted into BGP dynamically and BGP can't tell where they came from because they bypassed the IP routing table.

A router 'speaking' BGP will automatically announce the best routes it knows that it finds in it's own IP routing table, therefore redistribution is unnecessary. As a general rule, redistribution can cause problems, especially when exterior routes are redistributed into the IGP.

However if you are attempting to make the routes you are announcing to appear more stable, a common technique is to create several aggregate null routes, and turn off synchronization. With network statements in place to announce aggregates that match the static null routes, the BGP routes will always be announced, and never flap unless your physical connection supporting your eBGP is down. This configuration makes your network more stable, and allows BGP to converge more quickly.