Chapter 10. Designing Stable Internets

This chapter covers the following key topics:

• Route instabilities on the Internet— Briefly examines the most common causes of route instability.

• Controlling route and cache invalidation— Cisco offers a soft configuration feature that enables administrators to reconfigure attributes on the fly with minimal repercussions for routes and cache.

• BGP route refresh— Border Gateway Protocol (BGP) route refresh provides a mechanism to apply new policies by requesting a fresh set of routes from a peer without having to reset the BGP connection or flap the route announcements.

• Route dampening— BGP's route dampening feature identifies and suppresses unstable routes for better reliability within and outside the autonomous system (AS).

Establishing and maintaining route stability within and among networks is crucial to ensuring reliable Internet connectivity. A number of design flaws and problems can contribute to destabilizing connections to the Internet. This chapter explores some of the causes of route instability and techniques for reducing it.