Cisco - Designing Large Scale Service Provider Dial Networks with OSPF

To design a dial network is a challenging task for Internet Service Providers (ISPs). Each ISP uses a unique method to design dial networks. However, all ISPs share the same areas of concern when they design dial networks, as listed here: • How must the pool routes be propagated into the ISP core? • What routing protocol must be used to carry those routes into the core? • Should those dialup routes be summarized before sending into the core? • What must be taken into account when the pools are distributed? • What happens if the pools are static? This document addresses most of the questions above and deals with the design practices of using the Interior Gateway Protocol (IGP) Open Shortest Path First (OSPF) in an ISP dial environment. OSPF is often used in the core network of ISPs. In this document, we avoid introducing a separate protocol for carrying the dial pool routes we use OSPF to propagate the dial pool routes into the core.