capitulo 6 ccna 4

capitulo 6 ccna 4.Troubleshooting routing protocols in real-world interconnects can be very complex, even more complex than the more difficult questions on the CCNA exam. Defining a generic troubleshooting process that can be applied to both simple and complex routing protocol problems requires a lot of discussion, which is only half the effort required to prepare for the CCNA exam. This chapter provides a straightforward approach to routing protocol problems, especially since the depth and complexity of the problems covered are similar to CCNA exam questions.If a test question appears to be a routing protocol-related failure, candidates can use the following method to quickly identify some common configuration errors-even if no configuration is listed. The method has the following 3 main steps. Step I Analyze the design plan for the interconnected network to determine which interface's routing protocol should be enabled and which router should be expected to be a neighbor router. Step 2 Verify that routing protocols are enabled for each interface (as in Step 1). If it is not enabled, identify the root cause and resolve thefix the problem.Step 3 Verify that each router has established the expected neighbor relationship. If not, identify the root cause and resolve the problem.For example, for those marked with an asterisk in Figure 11-2, each router should have routing protocols enabled on each of the routing interfaces shown in the figure. In addition, routing protocol neighbor relationships should be established between R1 and R2 and R1 and R3, but there is no such relationship between R2 and R3.Although these concepts depicted in Figure 11-2 should be more or less obvious by now, this chapter still discusses how some of the most common configuration errors affect the interfaces used by routing protocols and whether routing protocols create neighbor relationships. 11.2.2 Interfaces Enabled Using Routing Protocols This subsection explains the second major troubleshooting step outlined earlier in this chapter: how to verify which routing protocol is enabled on an interface.11.2 Basic Content 225EIGRP and OSPF configuration Routing protocols can be enabled on an interface by using the network router subcommand. For any interface that matches the network command, the routing protocol attempts to perform the following two actions.,,. Word 20. Attempts to identify potential neighbors in the subnet to which the interface is connected. I dot . Finds the subnets connected to the interface.Also, the passive-interface router subcommand can be configured so that the router does not try to find the neighbors on the interface (the first action just listed out), but still advertises the connected subnets (the second action).