Hop Count

• Only used by the Routing Information Protocol (RIP), this simplified metric counts how many other routers a packet will have to pass through before it reaches the destination. Codified by the Internet Engineering Task Force (IETF) in RFC 1388, RIP and its successor RIP2 specify a maximum "hop count" of 15 before the route is considered unusable.
  
  

Bandwidth

• The Interior Gateway Routing Protocol commonly uses two metrics to evaluate a path, one of which is bandwidth. The bandwidth metric is calculated by taking the bandwidth of a connection and dividing it by 10,000,000. The Interior Gateway Routing Protocol actually has a total of five different metrics available to help evaluate the path, but the other three values are, by default, set to values that render them ineffective. Cisco Systems highly recommends that these other three metrics be left alone.
  
  

Delay

• The second metric used by IGRP is delay. Delay is used hand-in-hand, by default, with the bandwidth metric. The delay value has 1,000 added and is divided by 10. That number is added to the previously calculated bandwidth metric to determine the "cost" of that path.
  
  

OSPF Link States

• For compatibility reason, any interface running the Open Shortest Path First (OSPF) protocol is automatically given a cost of 10. OSPF does not use a metric calculation when determining the best path within OSPF-enabled networks. OSPF is an open-source protocol, which only sends multicast updates to its designated "area" when a change is detected. This allows OSPF to converge (a term used when every router has an up-to-date view of the routers in their area) faster than most other routing protocols.
  
  

Static Routes

• Though not a metric, any route manually configured in the router will take precedence over one discovered through routing metrics such as RIP or IGRP.