Metric increase for a specif route

A route metric specifies the cost of a route to a specified destination address. The following factors often affect the route metric:

• Path length

  Path length is the most common factor that affects the route metric. Link-state routing protocols allow you to assign a link cost for each link to identify the path length of a link. In this case, the path length is the sum of the link costs of all the links that packets pass through. Distance-vector routing protocols use the hop count to identify the path length. The hop count is the number of devices that packets pass through from the source to the destination. For example, the hop count from a router to its directly connected network is 0, and the hop count from a router to a network that can be reached through just another router is 1. Other lengths can be deduced in the same manner.

• Network bandwidth

  Network bandwidth is the transmission capability of a link. For example, a 10-Gigabit link has a higher transmission capability than a 1-Gigabit link. Although bandwidth defines the maximum transmission rate of a link, routes over high-bandwidth links are not necessarily better than routes over low-bandwidth links. For example, when a high-bandwidth link is congested, forwarding packets over this link will require more time.

• Load

  The load is the degree to which a network resource is busy. You can obtain the load by calculating the CPU usage and packets processed per second. Continually monitoring the CPU usage and packets processed per second helps you learn more about network usage.

• Communication cost

  The communication cost is the operating cost of a route over a link. The communication cost is another important indicator, especially if you do not care about network performance but are concerned about the operating expenditure.