What Is Gigabit Ethernet?

What you need to know about this high-speed communication standard

Gigabit Ethernet is part of the Ethernet family of computer networking and communication standards. The Gigabit Ethernet standard supports a theoretical maximum data rate of one gigabit per second (1,000 Mbps).

Information in this article applies broadly to a collection of technologies used to transmit data via Ethernet.

How Does Gigabit Ethernet Work?

It was once believed that achieving gigabit speeds with Ethernet would require the use of fiber optic cables or other special network cable technology. Fortunately, those are only necessary for long distances. For most purposes, Gigabit Ethernet works well using a regular Ethernet cable (specifically, the CAT5e and CAT6 cabling standards). These cable types follow the 1000BASE-T cabling standard (also called IEEE 802.3ab).

How Fast Is Gigabit Ethernet in Practice?

Because of factors like network protocol overhead and re-transmissions due to collisions or other transient failures, devices cannot actually transfer useful message data at the full 1 Gbps rate. Under normal conditions, the effective data transfer might reach 900 Mbps, but the average connection speed varies based on many factors.

For example, disk drives can limit the performance of a Gigabit Ethernet connection on PCs. There's also the factor of bandwidth limiting the connection. Even if a whole home network can get download speeds of 1 Gbps, two simultaneous connections immediately halve the available bandwidth for both devices. The same is true for any number of concurrent devices.

Some home routers with Gigabit Ethernet ports might have CPUs that are unable to handle the load needed to support incoming or outgoing data processing at the full rates of the network connection. The more client devices and concurrent sources of network traffic, the harder it will be for a router processor to support maximum speed transfers over any connection.

How to Tell if a Network Supports Gigabit Ethernet

Network devices provide the same RJ-45 connection type whether their Ethernet ports support 10/100 (Fast) or 10/100/1000 (Gigabit) connections. Ethernet cables are often stamped with information about the standards they support, but they do not indicate whether the network is actually configured to run at that rate.

To check the speed rating of an active Ethernet network connection, find and open up the connection settings on your computer. In Windows 10, for example:

  1. Open the Windows Control Panel.
  2. Select Network and Internet.

    Select Network and Internet.
  3. Select View network status and tasks.

    Select View network status and tasks.
  4. Select Ethernet to open the status window and view the speed.

    Select Ethernet to open the status window and view the speed.

Connecting Slower Devices to Gigabit Ethernet

All newer broadband routers support Gigabit Ethernet along with other mainstream computer network equipment, but Gigabit Ethernet also provides backward compatibility to older 100 Mbps and 10 Mbps legacy Ethernet devices.

Connections to these devices function normally but perform at the lower rated speed. In other words, when you connect a slow device to a fast network, it will only perform as fast as the slowest rated speed. The same is true if you connect a gigabit-capable device to a slow network; it will only operate as fast as the network allows.