cisco ccie collaboration written dumps

cisco ccie collaboration written dumps.19.3.1 Loopback InterfacesA loopback interface is a logical virtual interface on a router. Routers do not have any loopback interfaces by default, but it is easy to create them. All IOSes support loopback interfaces, and you can create as many loopback interfaces as you need. Loopback interfaces are like physical interfaces on a router: you can assign addressing information to them, include their network numbers in routing updates, and even use them as endpoints for IP connections (such as Telnet and SSH connections).Exam Essentials Loopback interfaces are logical interfaces that are always enabled and can be created using the command interface loopback.Here are some reasons why you might want to create a loopback interface.. To assign a router ID to an OSPF routero . For testing purposes. because such interfaces are always enabled.. For use as an endpoint for special connections (such as GRE tunnels or IPsec connections) because such interfaces are always enabled.The OSPF router ID is selected when the OSPF routing process starts, which happens when you manually execute the command router ospf or when the router loads the configuration during startup. Therefore, if you create a loopback interface after OSPF is enabled, its IP address will not be used as the router ID; however, if you reboot the router, the IP address of the loopback interface will be used as the router ID by default. therefore, it is recommended that you create the loopback interface and assign it an IP address before enabling OSPF, to avoid uncertainty about what the router's router ID is.To create a loopback interface, use the following command.Router(config)# interface loopback port_# Router(config-if)# ip address IP_address subnet_maskAs you can see, creating a loopback interface is fairly easy. You can specify a port number of 0.2147483647, but it only makes sense locally. Once you enter a loopback interface, you can execute almost any interface command; for example, you can assign it an IP Wo using the command ip address