To determine OSPF link costs, consider the following factors:
1. Bandwidth: OSPF link costs are calculated based on the bandwidth of the link. The higher the bandwidth, the lower the cost.
1. Delay: The delay on the link also affects the link cost. A link with lower delay will have a lower cost.
1. Reliability: A link’s reliability and availability also affect its cost. If the link is unreliable, it will have a higher cost.
1. MTU: The Maximum Transmission Unit (MTU) of a link can also affect its cost. A link with a higher MTU will have a lower cost.
1. Admin Distance: The administrative distance used to reach the destination, which can be dependent on various factors like routing protocol priority or static routing.
Based on these factors, the link cost can be calculated by using the following formula:
cost = reference bandwidth / link bandwidth
Where “reference bandwidth” is a pre-defined value (usually 100 Mbps) and “link bandwidth” is the actual bandwidth of the link in question.
