Interdomain Internet Routing

This paper clearly explains the routing mechanisms that connect administrative domains in the Internet topology. The Internet comprises Autonomous Systems, administered by a single commercial entity, that exchange reachability information with one another using the Border Gateway Protocol (BGP). Unlike intradomain routing, interdomain routing requires a great emphasis on scalability. Internet Service Providers (ISPs) can engage in transit relationships, financial agreements to share access to each other's routing tables. Peering relationships, on the other hand, involve granting access to a subset of each other's routing tables for mutual benefit. In the commercial reality, interdomain routing decisions must be based not only on reachability but also economic considerations. For example, an ISP may deny access to a competitor or seek a financial gain before agreeing to transit packets from another AS. Rather than looking to optimize the path cost, BGP revolves around scalability, policy and cooperation.

The content of this paper is still very relevant today and the clarity of the explanation makes it an essential read in the syllabus. This is the first paper that has explored the real-world, commercial aspect of the Internet rather than focusing on theoretical mechanisms and hypothetical situations. Perhaps some elaboration on potential security threats for interdomain routing would have been appropriate. Overall, this was a very informative read.