10.5 Chapter Summary

As this chapter comes to a close, so does this book's discussion of BGP and interdomain routing. The case studies in this chapter are a foundation for further exploration into the BGP protocol and JUNOS implementation.

This chapter discussed path selection and a few of the methods BGP uses to select an active path such as Router ID and AS_PATH . It also examined some of the more common advanced features of path selection through the use and manipulation of AS_PATH prepending, LOCAL_PREF , MED , and NEXT_HOP . It has shown how BGP scaling can be used to make our administration of a large BGP network easier. The use of route reflectors can eliminate the IBGP full-mesh problem. The use of confederations can conquer not only the IBGP full-mesh problem, but also scale IGP and BGP domains into smaller more manageable domains.

Lastly, you should have an understanding of route aggregation. Aggregation can be used to simplify prefix advertisement. With aggregation you can reduce the potential for route flaps throughout the network and give attention to specific routes that have certain characteristics that need to be passed directly to upstream neighbors.