This OID stores an alternative cost metric (on a scale of about -2 billion to +2 billion) for sending messages with a different quality-of-service type over a particular logical line to an adjacent node. Engineers use multiple metrics to optimize routing for different traffic types—some routes may be good for voice but expensive for data. For example, a value of 75 might indicate the cost for real-time traffic on this line, while the Metric 1 value of 100 is the cost for best-effort traffic.