Path Selection
Path selection involves applying a routing metric to multiple routes, in order to select (or predict) the best route.
In the case of computer networking, the metric is computed by a routing algorithm, and can cover such information as bandwidth, network delay, hop count, path cost, load, MTU, reliability, and communication cost (see e.g. this survey for a list of proposed routing metrics). The routing table stores only the best possible routes, while link-state or topological databases may store all other information as well.
Because a routing metric is specific to a given routing protocol, multi-protocol routers must use some external heuristic in order to select between routes learned from different routing protocols. Cisco's routers, for example, attribute a value known as the administrative distance to each route, where smaller administrative distances indicate routes learned from a supposedly more reliable protocol.
A local network administrator, in special cases, can set up host-specific routes to a particular machine which provides more control over network usage, permits testing and better overall security. This can come in handy when required to debug network connections or routing tables.
Read more about this topic: Routing Algorithms
Famous quotes containing the words path and/or selection:
“If you are ambitious of climbing up to the difficult, and in a manner inaccessible, summit of the Temple of Fame, your surest way is to leave on one hand the narrow path of Poetry, and follow the narrower track of Knight-Errantry, which in a trice may raise you to an imperial throne.”
—Miguel De Cervantes (1547–1616)
“Historians will have to face the fact that natural selection determined the evolution of cultures in the same manner as it did that of species.”
—Konrad Lorenz (1903–1989)