Chapter 12. Configuring Effective Internet Routing Policies

This chapter covers the following key topics:

• Symmetry, redundancy, and load balancing— Configuration examples for dynamically and statically learned defaults, multihoming to single and multiple providers, load balancing, and customers sharing a backup link.

• Following defaults inside an AS— Configuration examples for setting defaults in a variety of architectures. This section examines a particular routing problem assuming a variety of different IGPs.

• Policy routing— A configuration example for routing based on source rather than destination.

• Route reflectors— A practical example of using route reflectors in conjunction with peer groups.

• Confederations— A practical example of how to configure confederations.

• Controlling route and cache invalidation— Syntax and a practical example of BGP's soft reconfiguration feature and BGP's Route Refresh capability.

• BGP Outbound Route Filter (ORF) capability— BGP ORF is enabled by BGP capabilities and is used to allow a BGP neighbor to "push over" its inbound prefix-list filter. We'll discuss the advantages of BGP ORF, as well as provide configuration guidelines.

• Route dampening— Syntax and a practical example of BGP's route dampening feature.

Chapter 11, "Configuring Basic BGP Functions and Attributes," covered configuration examples for all the basic functions and attributes of BGP. In this chapter, we will consider examples that address the challenging, potentially conflicting design goals of routing architecture. We will also look at examples designed to help manage growing, complex networks.

Perhaps the most challenging part of configuring your network's routing architecture is determining what your routing policies should be. This step, of course, must come before the actual configuration process, and there is no simple, lockstep method for determining your policies. A careful analysis of network needs, behavior, and potential growth will reveal a unique set of problems and optimal solutions for every network.