4.1 What is 'Peering' an Introduction

This chapter looks at the essential ingredient of the Internet how the many different Internet service providers connect to each other so that any one on the Internet can reach any thing on the Internet. The general term used to describe how ISPs connect to each other is 'peering'. The implementation of an ISP's peerings will be a major deteminant of the performance of the services the ISP offers to its customers. This chapter is an introduction to both the key principles and the art of peering.

Peering is simply defined as an interconnection between two networks which facilitates the inter-exchange of data, and has become one of the most important and most widely debated subjects within the Internet industry. For an Internet service provider (ISP), it has a direct impact on the cost base, revenues, market position, customer perception, and network performance. There is no doubt that, as the Internet grows and the volume of traffic increases, the complexity of interconnections between the networks will increase. From an engineering perspective 'peering' is used as a generic description to cover an interconnection between two Internet networks. However, other terminology must be employed to describe the commercial framework that underpins such interconnects. Although many of the terms are loosely exchanged and change frequently, the following will be used for consistency in this chapter.

• Interconnection

  This is a physical and direct interconnection, a circuit, between two networks which facilitates the...