Routing Strategies

Routing problems arise when telephone traffic becomes aggregated.

Possible protocols for handling networks with local overloading:

1. Collect information about the current traffic at all links, calculate the path with lightest traffic, and route the call along that path.
2. Base the routing strategy on previously-gathered statistics on traffic patterns at all links and time periods. (These statistics should be updated periodically).

Strategy #2 is the universally-accepted strategy in real telephone networks. It turns out that aggregated telephone traffic is highly predictable, and telephone links and switches are very reliable. Hence, the approximate load can be pre-computed for each pair of switches for every interval of every day, allowing routes to be determined in advance.