Description: Link Cost is a metric used in routing protocols such as BGP (Border Gateway Protocol) and EIGRP (Enhanced Interior Gateway Routing Protocol) to determine the best route for data to travel across a network. This metric is based on various factors, including link speed, latency, traffic load, and link reliability. In the context of wide area networks (WAN), Link Cost allows routers to evaluate and select the most efficient routes for data traffic, thereby optimizing network performance. A lower cost generally indicates a more preferred route, while a higher cost may signal a less efficient path. This metric is crucial for routing decision-making, as it directly influences service quality and end-user experience. In summary, Link Cost is an essential component in traffic management, ensuring that data is transmitted effectively and efficiently across various network topologies.
History: The concept of Link Cost has evolved with the development of routing protocols. In the 1980s, with the introduction of protocols like RIP (Routing Information Protocol), simple metrics based on hop count were established. However, as networks became more complex, more advanced protocols like EIGRP and BGP emerged, incorporating more sophisticated metrics, including Link Cost. These protocols allowed for better traffic management and greater routing efficiency, adapting to the changing needs of modern networks.
Uses: Link Cost is primarily used in routing decision-making within WANs and other types of networks. Protocols like EIGRP use this metric to calculate the best route to a destination, considering factors such as link speed and latency. In BGP, Link Cost helps determine the optimal route between different autonomous systems, which is crucial for Internet connectivity. Additionally, it is applied in optimizing network performance, allowing network administrators to adjust metrics according to specific traffic needs.
Examples: A practical example of using Link Cost can be seen in an enterprise network using EIGRP. If a router has multiple routes to a server, it will calculate the Link Cost for each route and choose the one with the lowest cost. In the case of BGP, an Internet service provider may use Link Cost to select the best route for traffic between different geographic regions, ensuring efficient data delivery.
