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Justifying 2.5G/5G Ethernet

June 15, 2015
Why is an Institute of Electrical and Electronics Engineers standards group working on a new version of Ethernet for 2.5G and 5G speeds, and how can they justify the development of a wireless connection that runs at slower speeds with all the recent development in 10G, 40G, and even 100G Ethernet?
Image courtesy of ThinkStock.

In case you have not heard, there is a new, slower (!) version of the ubiquitous Ethernet LAN in the works. As you probably know, most recent development on the Ethernet standards has involved higher speeds—10G, 40G, and 100G versions are already in use and work is being done on 400G versions. So what’s with the slower speeds?

At the request of multiple manufacturers of Wi-Fi access points (APs) and networking chips as well as the Ethernet Alliance, the IEEE 802.3 standards group is developing a version of Ethernet for 2.5G and 5G speeds. With the new Wi-Fi standard 802.11ac being deployed, the higher data rates cannot be handled by most installed APs that use 1G Ethernet for connection to the network. While 10G Ethernet equipment is available, it requires an upgrade to the wired network. Most wired networks still use the massive installed base of CAT5e and CAT6 that does not support 10G up to 100 meters. One estimate is that there are 70 billion meters of CAT5e/6 out there and it is slowing down the new 802.11ac Wi-Fi connections. Wave 1 version of 11ac delivers a maximum speed of 1.3 Gb/s. The latest Wave 2 version permits speeds up to 6.8 Gb/s. A 2.5G/5G version of the wired infrastructure will allow the speed potentials to be reached without a wiring upgrade.

Besides the need from the Wi-Fi industry, a 2.5G/5G version will also aid in other applications such as enterprise infrastructure, cellular Wi-Fi offloads, small cells, security cameras, and multiple industrial uses.

A major supporter of the new standard is the Ethernet Alliance (www.ethernetalliance.org). The Alliance is a global consortium of companies and other organizations that support the continued success and expansion of Ethernet.   

A new organization supporting the push for a 2.5G/5G standard is NABSE-T Alliance (www.nbaset.org).  Now with 34 members, the Alliance is working with the IEEE 802.3bz Task force to build the new standard. The goal is to support those speed levels over 100 meters of CAT5e, CAT6, and CAT6A twisted-pair.

The IEEE 802.3bz Task Force has already adopted a baseline technology for the physical layer specifications of 2.5GBASE-T and 5GBASE-T. The plan is to also support the Energy Efficient Ethernet and Power over Ethernet (PoE) options. It is estimated that a final definition and ratification will occur before the end of 2015.  For an update on the status of this standard go to standards.ieee.org/develop/project/802.3bz.html.

Everyone in industry loves this new version of Ethernet. No doubt, the IEEE working group will fast-track this standard.  And you can be sure that the chip and equipment vendors are already at work on new products. The Ethernet story is ongoing. What can we possibly expect in the future? A 400G version seems to be a given. What about a 1 Terabit version?  But who would have predicted a 2.5G/5G version?  This just shows the flexibility of Ethernet to adapt to changing technological advances and needs. It will be interesting to see what’s next.

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