Routing Matrix, Cost and Administrative Distance

The Matrix Routing service is an HTTP JSON API that calculates routing matrices, travel times, and/or distances, of up to 10,000 origins and 10,000 destinations. A routing matrix is a matrix with rows labeled by origins and columns by destinations. Each entry of the matrix is the travel time or distance from the origin to the destination.

Routing Metrics and Costs

• Metrics are cost values used by routers to determine the best path to a destination network.
• Several factors help dynamic routing protocols decide which is the preferred or shortest path to a particular destination. These factors are known as metrics and algorithms.
• Metrics are the network variables used in deciding what path is preferred in terms of these metrics.
• For some routing protocols, these metrics are static and may not be changed. For other routing protocols these values may be assigned by a network administrator.
• The most common metric values are a hop, bandwidth, delay, reliability, load, and cost.
  

Administrative Distance

• Most routing protocols have metric structures and algorithms that are not compatible with other protocols.
• In a network with multiple routing protocols, the exchange of route information and the capability to select the best path across the multiple protocols is critical.
• Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols.
• Administrative distance defines the reliability of a routing protocol.
• Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value.