Content

| 9.10 |  | BGP Redistribution |
| 9.10.3 |  | Injecting information statically into BGP |

Today, injecting information statically into BGP has proven to be the most effective means to ensure route stability. Of course, this method also has drawbacks. To statically inject information into BGP, the IGP routes, or aggregates, that need to be advertised to other peers are manually defined as static routes. This ensures that these routes will never disappear from the IP routing table and hence will always be advertised. Administrators are often uncomfortable advertising routes to networks that might be down or unreachable. Whether it is appropriate to inject this information statically depends on the particular situation.

For example, if the route is advertised to the Internet from a single point, then advertising a route that is actually down is essentially debatable. Hosts trying to access that destination will fail, regardless of whether the route is advertised. On the other hand, if a route is advertised to the Internet from multiple points, then advertising the route statically at all times might end up creating a black hole for traffic. If problems inside the AS do not allow the border router to reach the network that it is advertising, traffic to that destination will be dropped. This happens even though it could have been reached from some other entry point.