RFC 2791 (rfc2791) - Page 3 of 26
Scalable Routing Design Principles
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RFC 2791 Scalable Routing Design Principles July 2000 characteristics of today's large networks and the associated routing scaling issues. Section 5 explores routing protocol scalability, and Section 6 presents scalable routing design principles. Section 7 provides a conclusion to the document. 2. Common Routing Design Goals The basic goals a routing system should achieve are as follows: o Stability o Redundancy and robustness o Reasonable convergency time o Routing information integrity o Sensible and manageable routing policy The challenge of designing routing in a large network is not only to achieve these basic goals but also to make the routing system scale. 3. Characteristics of Today's Large Networks Today's large networks typically possess the following features: o They are composed of a large number of nodes (routers and/or switches), typically in the hundreds. Some provider networks include customer CPE routers within their administrative domain, which increases the number of nodes to thousands. o They have rich connectivity to meet redundancy and robustness requirements, and they consequently have complex topologies. o They are default-free; that is, they carry all the routes known to the entire Internet. Currently, the total number is approximately 70,000. o The customer aggregation routers inside the large networks connect sometimes hundreds of customer routers. These characteristics impose a direct challenge to the routing scalability of the network. 4. Routing Scaling Issues Today, the main issues surrounding routing scaling are: i) excessive router resource consumption, which can potentially increase routing convergency difficulties thus destabilize a network; and ii) routing complexity, resulting in poor management of network, producing low service quality. Yu Informational
