Wag54g Router Unnumbered Ip Functionality And Command-line Configuration

In the time that the network is developing speedily, the router plays a very important role, primarily employed in the connection of WAN, interlinkage of heterogeneous networks and segment of networks, being one of the cores constructing the networks. A router is composed of hardware and software, which has the properties of embedded system.The platform the paper study is WAG54G router selled by Linksys Corp. , whose integral name is Wireless-G ADSL Gateway. The software of WAG54G router is built on the Linux operating system contributed to its rich and strong network function, inherently steady character and ease to integrate all kinds of different hardware drivers, etc. The paper focuses on the design and implementation of the function of Unnumbered IP and Command Line Interface configuration abbreviated by CLI on the WAG54G router.The paper firstly discusses the general principal and application of Unnumbered IP. Unnumbered IP functions in saving IP address on point-to-point connection, which has no RFC standard, whose basic principle is not to distribute the effect IP address on the point-to-point interface, in other words, the IP address on the point-to-point interface has almost no chance in appearing in any existing packages on Internet. In succession, the particularly implemental principal and detailed design of Unnumbered IP that fits the WAG54G router is illustrated combined with its applied background: the WAG54G router is mainly used by family as ADSL router, through dialing in the way of PPPoE, the PPP linkage featured by point-to point to be established between the ADSL interface of the router and the remote NSP/ISP's access server, after which, by adding new function that enables negotiating the subnet mask between the two entities on PPP linkage to the standard PPP protocol implementation, the flexible and adaptable subnet is successfully acquired on the PPP linkage, as is the base on which the acquired subnet can be used to configure the Ethernet interface of the router and the ADSL interface is reassigned by the special IP address that seldom exists in the packages running on Internet such as 1.1.1.1 to make it the so-called Unnumbered IP interface, through which, except the IP address within the acquired subnet that is already consumed by the Ethernet interface of the router, all the other IP addresses within it can be assigned to the LAN connected to the router by its DHCP service.The other topic of the paper focuses on CLI which helps user interactively configure the router, as is familiar with and preferred by the professional users.After the principal of CLI is explained including the partition of the commands' modes and the principle of the NVRAM used to save and fetch the configuration variables, the design and implementation of the CLI system are specified. In order to approach the style of the commands to the Cisco router and easily change the commands to the customers' requirements, the flexible data structures and software architecture aredesigned. The CLI system can be partitioned by master control module, command register module, functional keys disposal module, command parser module and command execution module.