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best ccna dumps 200-301.Figure 9-11 Effect of Bandwidth on ElGRP Metric Calculation In general, a good metric strategy in a network using EIGRP is to use the default value of the LAN interface to match the bandwidth of the WAN to the actual Layer 1 (Layerl) speed. This way EIGRP will usually always choose the best route.Now that you know the details of how EIGRP establishes neighboring router relationships, exchanges routing information, and calculates the best route, the rest of this section focuses on the most interesting part of EIGRP: how EIGRP converges to form a loopback-free route.Avoiding loopbacks is one of the most difficult problems faced by all dynamic routing protocols. Distance vector protocols overcome this problem using a variety of tools, some of which trigger a few minutes of convergence time when a link fails. Link-state protocols overcome this problem by having each router keep complete topological information about the network, so by running somewhat complex mathematical models, routers can avoid any loopbacks.EIGRP avoids loopbacks by keeping some basic topology information. the reason EIGRP keeps some topology information is the same as OSPF - to allow faster convergence and not cause loopbacks when new routes are used. In essence, EIGRP keeps a record of every possible next-hop router and some detailed information related to those routes, but no topology information beyond the next-hop router. This sparse topology information does not require complex SPF algorithms to achieve fast convergence and less overhead, and to avoid loopbacks.4.2 Foundational Elements 199Feasible Distance and Notification DistanceFirst, before discussing how EIGRP converges, you need to understand a few other EIGRP terms. In EIGRP, the local router needs to consider its own computed metric for each route, but at the same time, the local router also has to consider the computed metric of the next-hop router arriving at the same destination subnet.EIGRP devises specialized terms for these metrics, as follows.[Rich & Feasible Distance (FD): the metric of the best route to the subnet, this value is computed in the router.. Reported Distance (RD): the next-hop router best metric for the same subnet.In general. the definition is easier to understand when given as an example. Use the same notification method as in Figure 9-10 earlier. Figure 9-12 gives the two calculations made by R1. One calculation finds the own metric (FD) for a certain route from R1 arriving at subnet 10.1.3.0/24, as discussed in the explanatory text of Figure 9-10. Another computation uses the metric component received from R2's update to compute R2's own computed metric for reaching the unified subnet from R2. the second computation for R1 based on R2's information (slowest bandwidth of 100 000 kbit/s and cumulative delay of 100 microseconds) is the RD for that path for R1.