Loopback Interface Configuration

introduction introduction the loopback interface is a type of virtual interface once created, the physical layer of the loopback interface remains in an "up" state unless manually disabled due to this characteristic, the loopback interface can be applied in the following scenarios source address for device generated ip packets because the loopback interface address is stable and a unicast address, it is often regarded as an identifier for the device by allowing or prohibiting packets carrying the loopback interface address to pass through authentication or security servers, it is possible to permit or restrict packets generated by specific devices this simplifies packet filtering rules however, it should be noted that when using the loopback interface address as the source address for ip packets, routing configurations are needed to ensure the reachability of the loopback interface to the destination route dynamic routing protocols in certain dynamic routing protocols, when a router id is not configured, the loopback interface's ip address is used as the router id by default in the context of the bgp protocol, to ensure that bgp sessions are not affected by physical interface failures, the source interface for transmitting bgp packets can be configured as the loopback interface in band device management the loopback interface can be utilized for device management within the network infrastructure loopback interface configuration loopback interface configuration operation command description enter the system configuration view configure enter the loopback interface configuration view interface loopback id configure the loopback interface ip address ip address the ip address of the loopback interface can only be modified and cannot be deleted