What Are Console Cables and What Are They Used For?
Console cables — also known as Cisco cables, rollover cables and management cables — are designed for a specific purpose. They connect Cisco networking devices to terminals or PCs for configuration. Typically, the Cisco end will connect via RJ45, and the terminal end will conclude in a serial connection.
What matters most about console cables is the specific nature of the connection. This is not an Ethernet or networking connection. It is a terminal connection, and its purpose is to enable the connected computer to configure the networking device. This is true for older Cisco equipment and brand-new devices. Configuration is performed through the serial connection.
What Are the Primary Kinds of Console Cables?
Console cables come in many shapes and sizes and with a variety of connector types. There are three that are used more commonly than the rest, mostly because of the frequency with which you will see these different connectors.
A RJ45 to DB9 is probably the most well-known console cable today. Once upon a time, console cables were connected with improvised “kits” that were little more than a string of adapters on the end of a serial cable. Today, you can get an RJ45 to DB9 cable that replaces the “kit” with a single cord. As the name implies, one end is RJ45 and the other is DB9.
This is the most direct serial connection available, and it comes packaged with a wide variety of Cisco devices. It’s something of a standard, but despite that, it’s designed to communicate with terminals that have the DB9 port. If you want to connect it to a PC or laptop, you’ll likely need an additional adapter between the DB9 end and your USB port.
Another common console cable, the CAB-CONSOLE-USB, connects the USB on a terminal to a mini-B port on the Cisco device. You’ll notice the lack of RJ45 connectors. This is a specialized cable that services smaller, often portable devices. Despite the connection pieces, this is still a "serial" cable that enables terminal communication.
The CAB-CONSOLE-USB-RJ45 is arguably the most modern console cable. It ditches the less-used DB9 connector and streamlines your communication. It goes seamlessly from the console port on the Cisco device to a standard USB port on a PC. It’s the simplest way to create a terminal connection with modern equipment, and it is not a standard inclusion in Cisco hardware packages. A handful of these cables can make network control substantially faster and easier.
That is what you need to know about console cables. In the past, networking staff had to waste valuable time finding creative ways to bridge connections and configure devices. With modern console cables, that time is saved and networking is that much easier.