capitulo 9 cisco ccna v6

capitulo 9 cisco ccna v6.Further review of R2's showipprotocols command output, especially the shaded sections point out configuration errors. Typically, the section heading "Routing for Networks" refers to a shorthand version of the configuration. In this case, the shaded phrase **10.0.0.0 0.255.255.255 area 1" is the exact syntax of a network command on Router R2 minus "network" or network 10.0.0.00.255.255.255 area 1. Since Figure 11-4 shows that all ports on the design should be located in area0, reconfiguring the command to network10.0.0.00.255.255.255areaO, this solves that particular problem.The example concludes by showing a log message, generated and volunteered by the R2 router, which informs the console user that the router has received a Hello message from a router in a different area.Additional details can also be examined when the user examines the interface. Use the show interfaces and show ip interface brief commands to continue to examine the IP address, subnet mask, and interface status of the interface, which is meaningful information. In particular, it is helpful to note which interface is in the up/up state, because the routing protocol does not attempt to find neighbors or advertise connected subnets for interfaces that are not in the up/up state. These verification checks are discussed in detail in Chapter 5, "Troubleshooting IPv4 Routing", and will not be repeated here.11.2.3 Neighbor RelationshipsEach router must check every possible neighbor, and this subsection focuses on the large number of practical situations associated with it.At the most basic level, routing protocols can easily create neighbor relationships using HelloW. First, the routing protocol must be enabled at some interface. Second, the interface does not necessarily have to be configured as a passive interface, as this would prevent the routing protocol from sending Hello messages.In addition to the most basic process, the routing protocol actually has to check several other parameters to see if the router in question has become a neighbor. Both OSPF and EIGRP use Hello messages to learn of new neighbors and to exchange information to perform some basic verification checks. For example, in Example 11-5, an OSPF router cannot be a neighbor to another router in another area because all routers in a common subnet should be designed to be in the same OSPF area.After an EIGRP or OSPF router receives a Hello from a new neighbor, the routing protocol analyzes and examines the Hello message and compares that information with the local router's own settings. If the settings match, it is okay. Otherwise the router does not become a neighbor. Because there is no formal terminology for the items considered by these routing protocols, all this book will tentatively refer to these items as Neighbor Requirements oTable 11-2 lists the Neighbor Requirements for EIGRP and OSPF. Following the table, a selection of items from these EIGRP and OSPF settings are presented, again using examples based on those shown in Figure 11-3.Tip: Although it is important to learn and remember these items in the table, a read-through is required when first reading the contents of this chapter. It is not too late to memorize the details in the table by heart when you review it.