Graphical User Interfaces

Graphical user interfaces (GUIs) are a more user-friendly configuration tool. The operator does not need to remember a command language, but is led through a series of screens with spaces to fill in the necessary configuration information. Default values are provided automatically and context-sensitive help is often available. Advanced GUIs support point-and-click provisioning in which an operator can achieve a high level of management using a mouse to select devices and components and to drag and drop configuration objects.

The biggest benefit to a GUI is the way in which data retrieved from devices can be displayed. Although it is possible to just show tables of data as in the CLI output, these tables can be easily enhanced to allow the user to click on any piece of information to drill down further and see more details. Better still, the GUI can provide graphical representations of information, tracking data against time or mapping resources in physical space. A GUI can, for example, build a picture of a device by learning from it what components it has that are installed and operational, and can present this to the operator as though he or she were looking at the real device. Similarly, by connecting to multiple devices in the network, the GUI can present a single, graphical view of the entire network.

This latter feature means that the GUI must be capable of operating remotely and must not be limited to direct access on the managed device. Remote GUI access can be achieved in a variety of ways, including through the X/Open remote console protocols, but this requires that the complex graphical manipulation and presentation are performed on the managed device. It is more common to place the bulk of the function at the central management site on a dedicated computer and to have the GUI-based management program contact the managed devices using some form of communications protocol.

The GUI can be implemented "over the top of" the CLI so that all commands issued at the GUI are mapped to CLI commands that are sent to the managed device using Telnet. Data that are displayed by the GUI can be collected in the same way before being massaged to make the pretty screens. Alternatively, GUIs may use their own communications protocols and data formats to "talk" to devices with the benefit of a more condensed information exchange since only the raw data are sent without the lengthy text control commands and output strings.

There is still a place for configuration files in systems that are managed using a GUI. There is, however, a less obvious way to store the data. If the GUI is implemented over the top of the CLI either locally or for remote transmission, then it is obvious to store the configuration using the CLI commands, but if the GUI is implemented using direct access to configuration data structures, it is often tempting for an implementer to build a binary configuration store. This loses the benefits of the text-based configuration file described in the previous section and makes it difficult to handle a system with a GUI and CLI, so the most common approach is to convert the GUI configuration into the equivalent CLI commands before storing the information.

It is worth noting that despite the user-friendly aspects of a GUI, an experienced network operator or field engineer will often prefer to use the CLI. The CLI gives access to a fi ner level of control and a greater amount of information than the GUI, even if that information is not always formatted in the most readable way. Further, many engineers claim that they can operate with the CLI much faster than they can handle a GUI.