chapter 11

The planning and design process of a network contribute to the installation of successful and functional network. These include the proper selection of the LAN and WAN media types, their associated cables and connectors. By considering all of these, the interconnection of devices from end devices, to intermediary devices up to the network resources lead to an appropriate decision that could help to improve and enhance network performance. In addition to that determining the number of hosts and subnets in a network and planning for future growth also contribute for a good network design and planning.  Intermediary devices are important device in a network, they used to interconnect devices and even to other nieghboring networks whether a LAN or WAN network. Configuring these devices properly in a secure manner would mean a good network administration. Routers and switches are just hardware components that are always dependent to the software that operate them in order to function. Since cisco is considered the backbone of the networking today, they provide an operating system that would manage and operate on the different cisco devices. This OS is called the INTERNETWORK OPERATING SYSTEM. It is used for routers, LAN switches small wireless access point. It also provide basic services in routing and switching function, reliable and secure access to network resources as well as network scalability. Ordinarily, CISCO devices were generally accessed through the command line interface (CLI) and stored in a non-volatile memory called flash. Routers and even switches can be accessed through different methods for the purpose of configuring these devices. The different access methods such as console, telnet/ SSH and by the use of AUX port offers various features and work at different environment. Each method uses security features to avoid unauthorized access. Some of these access methods work with or without active networking services present. The network administrator is a person who has primary control of the network configuration especially network configuration and also defines desired functionality of a CISCO device.  There are two types of configuration files: the start-up configuration file and the running configuration file. These configuration files are stored in a non-volatile random access memory. The CLI uses hierarchical structure for the modes of configuring CISCO devices. The major modes involved were user executive mode, privileged executive mode and the global configuration mode. Each mode is used to perform a specific function and has particular set of commands that are available when in that mode. This hierarchical structure mode provides security support at each mode level for authentication. Each mode has its own set of commands that are used to configure CISCO devices. The commands are the combination of keywords use to execute after the configurations. A command may be used to show the configuration or do some actions to the router and it could also help to show commands to guide the administrator of the appropriate command to be used by the context help command. There are also types of error messages in order to inform the users of the errors they committed. All configurations made must be stored in NVRAM for future access and configuration. Routers and switches have what we called interfaces and each interface must be configured with the right IP address and subnet mask in order to connect each other and send a packet within a network. After configuring all the CISCO devices with appropriate ip addresses and other information there is a need to test the connectivity, this is possible by pinging other devices in a network. Documentation is very helpful to facilitate monitoring and troubleshooting network performance, this is done through creating a network baseline that conduct a study of the network at regular intervals to ensure that the network is working as designed