Chapter 8. Network Design Scenarios

This chapter looks at deploying Integrated IS-IS in various networking environments from a design perspective. IP-only networks are examined, based on Internet service provider (ISP) deployments. The discussions focus on using Integrated IS-IS in point-to-point and multipoint design scenarios. Packet over SONET (PoS), a common high-speed-to-point transport technology is used as the premise for exploring IS-IS configuration over point-to-point links. The multipoint section looks at Frame Relay, Asynchronous Transfer Mode (ATM), and, in general, mesh transport environments, all of which are currently deployed on a large scale in real networks. The chapter then considers strategies for migrating from other protocols, both classful and classless, to Integrated IS-IS. Examples are provided to demonstrate how to carry out such migrations successfully. The coexistence of Integrated IS-IS with other Interior Gateway Protocols is discussed. In some cases, IS-IS must run alongside another IGP, usually on temporary during migration, yet sometimes, even permanently. Finally, this chapter covers how both IP and CLNP coexist in dual environments. Issues that might exist in dual deployments are highlighted.