Border Gateway Protocol (BGP) is the routing protocol used to exchange routing information across the Internet. It makes it possible for ISPs to connect to each other and for end-users to connect to more than one ISP. BGP is the only protocol that is designed to deal with a network of the Internet's size, and the only protocol that can deal well with having multiple connections to unrelated routing domains.

This book is a guide to all aspects of BGP: the protocol, its configuration and operation in an Internet environment, and how to troubleshooting it. The book also describes how to secure BGP, and how BGP can be used as a tool in combating Distributed Denial of Service (DDoS) attacks. Although the examples throughout this book are for Cisco routers, the techniques discussed can be applied to any BGP-capable router.

The topics include:

• Requesting an AS number and IP addresses
• Route filtering by remote ISPs and how to avoid this
• Configuring the initial BGP setup
• Balancing the available incoming or outgoing traffic over the available connections
• Securing and troubleshooting BGP
• BGP in larger networks: interaction with internal routing protocols, scalability issues
• BGP in Internet Service Provider networks