count of four indicates that data traveling along that path must have passed through four routers before reaching its final destination on the network. If there are multiple paths to a destination, the router, using RIP, selects the path with the least number of hops. However, because hop count is the only routing metric used by RIP in determining best path, it is not necessarily the fastest path. Nevertheless, RIP remains very popular, and is widely implemented. This is primarily because it was one of the earliest routing protocols to be developed. Another problem with using RIP is that a destination may be located too far away for the data to reach it. With RIP, the maximum number of hops that data can travel is fifteen. Because of this, if the destination network is more than fifteen routers away, it is considered unreachable. IGRP and EIGRP are routing protocols that were developed by Cisco Systems, Inc., therefore, they are considered proprietary routing protocols.IGRP was developed specifically to address problems associated with routing, in large multi-vendor networks, that were beyond the scope of protocols such as RIP. Like RIP, IGRP is a distance-vector protocol; however, when determining the best path, it also takes into consideration such things as bandwidth, load, delay, and reliability. Network administrators can determine the importance given to any one of these metrics. Or, allow IGRP to automatically calculate optimal path. EIGRP is an advanced version of IGRP. Specifically, EIGRP provides superior operating efficiency and combines the advantages of link-state protocols with those of distance-vector protocols. OSPF means "open shortest path first". A better description, however, might be "determination of optimum path", because this Interior Gateway Protocol actually uses several criteria to determine the best route to a destination. These criteria include cost metrics, which factor in such things as route speed, tr...
