Talk:Shortest path routing

SPF runs in small routing domains

We should not be suggesting that SPF is the Internet-wide routing algorithm, or, indeed, that there is any one algorithm. SPF is quite effective in networks, or hierarchical subareas of networks. Even real-world intradomain routing protocols such as OSPF use distance vector routing for their inter-area and external routes. The overall Internet (and large private system) Border Gateway Protocol uses path vector routing with a considerable number of policy extensions, the policy so dominating that BGP is not infrequently called a reachability protocol rather than a routing protocol. Howard C. Berkowitz 22:32, 24 December 2009 (UTC)

Good points. I can see there are some unintended suggestions in the second paragraph of the intro. How about "This article will explain a basic routing algorithm [1] commonly used in routing protocols for small to mid-sized networks." I'm still a little puzzled by what this means in real numbers. Peterson & Davie (p.267) say "fewer than a hundred nodes". The Python program in this article will compute a routing table of 3000 nodes in 1.2 seconds. In C, this would be more like 12 msec. Surely this is fast enough for a network where link costs change over a period of hours. --David MacQuigg 20:57, 25 December 2009 (UTC)