RFC 2791 (rfc2791) - Page 3 of 26
Scalable Routing Design Principles
Alternative Format: Original Text Document
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