Multi-gigabit Ethernet is a set of Ethernet standards that deliver speeds above the traditional 1 Gigabit per second, specifically 2.5 Gbps and 5 Gbps, over ordinary twisted-pair copper cabling that is already installed in most buildings. Defined primarily by the IEEE 802.3bz standard, it lets organisations increase network speed without the cost and disruption of replacing their existing cabling.

Why does multi-gigabit Ethernet exist?

For years, wired access networks ran at 1 Gbps, and the cabling installed to support it, Category 5e and Category 6, was rated for that speed at standard distances. Then wireless access points outgrew it. Wi-Fi 5 and especially Wi-Fi 6 and Wi-Fi 7 access points can move more than a gigabit of real traffic, which means a 1 Gbps wired uplink becomes the bottleneck: the access point can serve data faster than its cable can carry it back into the network.

The traditional fix was to jump to 10 Gigabit Ethernet, but 10GbE often requires higher-grade cabling (Category 6A) to run at full distance, meaning an expensive re-cabling of the building. Multi-gigabit Ethernet was created to fill the gap between 1 and 10 Gbps and, crucially, to do it over the cabling already in the walls.

How does it work over existing cabling?

Multi-gigabit Ethernet uses signal-processing techniques that let 2.5 Gbps and 5 Gbps run reliably over existing Cat5e and Cat6 cable at the usual 100-metre distance, speeds those cables were never originally certified for. Multi-gig switch ports are typically auto-negotiating: when a device connects, the port automatically settles on the highest speed the specific cable run can support, whether that is 1, 2.5, 5, or 10 Gbps. This backward compatibility means multi-gig ports work with older equipment too, simply running slower.

The practical result is a large increase in usable bandwidth, often 2.5 to 5 times, from cabling that is already in place, avoiding the cost, disruption, and downtime of pulling new cable through a building.

Multi-gig and Power over Ethernet

Multi-gigabit ports commonly combine higher speed with Power over Ethernet (PoE), so a single cable both connects and powers a device such as an access point or camera. This is important because the same devices that need multi-gig data speeds, modern high-density access points, also tend to draw more power. Multi-gig ports that support the higher PoE standards can deliver both the bandwidth and the power a demanding access point needs over one existing cable.

When is multi-gig needed, and when is it not?

Multi-gig is not required everywhere. For many devices and for older or lower-density access points, a standard 1 Gbps link remains perfectly adequate. Multi-gig earns its place in specific situations: high-density areas served by the latest access points, uplinks that are demonstrably saturating 1 Gbps, and deployments of Wi-Fi 6 and Wi-Fi 7 hardware that can exceed a gigabit of throughput. The sensible approach is to deploy multi-gig where the workload justifies it rather than as a blanket upgrade, matching the port speed to the actual throughput each device needs.