IP Routing Protocols

ESTABLISHING LINK COSTS AND PRUNING THE TREE

We know that each output link at each router has a value assigned to it that represents a metric (or possibly, but not likely, some combination of the TOS parameters). This value can be established by the network administrator. It is technically possible to establish link costs dynamically, based on queue lengths, delays encountered at the routers, and other performance criteria. However dynamic metrics are difficult to manage, and they are not used in connectionless networks like IP or Ethernet. Connection-oriented networks, such as ATM, can use dynamic metrics very effectively because bandwidth is set up for each connection, and OSPF can be used for ongoing advertisements. Once a connection is set ...