Keith Bromley
Sr. Manager, Product Marketing at Ixia

Command Line Interface: The ABCs of Network Visibility

February 8, 2017 by Keith Bromley

Computers do amazing things. And it doesn’t take a tech expert to know we’ve only scratched the surface. With driverless cars, 5G technology, and job automation on the horizon, computers will soon be doing more to support and sustain our way of life than ever before. But, on a very basic level, this all starts with one thing—we must be able to tell computers what we want them to do.

What is a Command Line Interface (CLI)?

Let’s first define what a user interface (UI) is. A user interface is a system by which a user and a computer interact—swapping information and instructions. A CLI is a type of user interface. Other types of UI include menu-driven interfaces, and graphical user interfaces (GUI).

Command line interfaces work by allowing the user to issue commands to the computer in the form of lines of text. Users must be familiar with a vocabulary of specific text commands that the computer will recognize and respond to. The user keys in the relevant command, and presses the ‘enter’ / ‘return’ button. The computer processes the command, and the result is displayed on screen. MS-DOS is a well-known example of a CLI system.

Typical Use Cases

CLI began life as the primary way in which people interacted with computer systems. Today, the graphical user interface (GUI) has surpassed CLI in popularity, but CLI continues to be used. This is because there can be benefits to using CLI. These include:

  • CLI requires fewer computing resources than GUI. This means CLI is a good option when there is limited processing power available.
  • It’s ideal for experts who are familiar with the necessary command vocabulary and who wish to execute (sometimes multiple) tasks at speed
  • It’s easier to automate processes using CLI

Considerations When Using CLI

There are a number of drawbacks to CLI, which is why a GUI is more commonly used. Some CLI drawbacks include:

GUI interfaces can be a lot faster – If more than a simple command or two is required to implement a function, a GUI is typically faster. Observations from Ixia systems show that the GUI can be four times or more faster.

CLI is not intuitive – CLI is reliant on the user being fluent in command vocabulary. The commands (which are not obvious) must be typed into the computer interface. A GUI removes this burden.

CLI is more error prone than a GUI interface – The cryptic command are very syntax-oriented which means that if anything is out of place when typing the commands, it may result in an error. Debugging errors is difficult and tedious.

CLI is not beginner-friendly – A proper GUI abstracts away the complexity for users which reduces training time and ultimately reduces the total cost of ownership of a monitoring equipment purchase.

CLI is visually sparse – This makes it uninteresting to look at and increases the probability of user fatigue and error.

Networks are already complexNetwork Packet Brokers (NPBs), which capture data from across the network and pass it on to the desired analytics, monitoring and security tools, have become the cornerstone of network security. NPBs are powerful, but they require careful management and configuration. NPBs that must be configured using a command line interface, require in-depth training and expertise. They offer little to no ease-of-use. And when IT teams are faced with hard-to-use configuration tools, valuable time, money, and effort can be wasted simply completing basic security tasks. Blind spots and network vulnerabilities become a risk.

More Information

GUI-based NPB configuration tools are more beneficial than their CLI-based counterparts. User-friendly NPBs built around a GUI, require less training, and can be operated by IT administrators of varying levels. They free up IT to take full advantage of NPB capabilities.  

An NPB with a proper GUI should deliver the following benefits:

  • Reduced capacity for errors, as the drag and drop interface means no risk of mistyping commands
  • Reduced need for special training – no new command vocabulary needs to be learned, allowing junior engineers to use Ixia’s configuration tools
  • Easier, and lower cost filter testing
  • Reduced need for troubleshooting

See for yourself how a graphical user interface reduces NPB management complexity by watching this video. Or read more on the tangible benefits of Ixia’s user interface over Gigamon’s here.

Ixia’s entire series of blogs on visibility are available now in the e-book Visibility Architectures: The ABCs of Network Visibility