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Ethernet has remained the dominant local area network technology since its introduction in the early 1980s. But that does not mean finding the best Ethernet networking foundation for your company is a cinch. The technology has evolved considerably, particularly in recent months.
What Ethernet is
Ethernet's low cost compared to the competing technology of the time was the initial reason for its popularity, and its ability to evolve to higher performance levels has guaranteed its continud use. Ethernet's original 10 Mbps throughput was well matched to the servers and workstations of the time. As computing power increased, Ethernet networking performance increased as well, with 100 Mbps Ethernet introduced in the mid-1990s. Successive performance increases have continued as the IEEE continues to update the original 10 Mbps 802.3 standard. Current versions of the standard specify operations up to 100 Gbps.
Cable technology has also continued to evolve. The original 10 Mbps Ethernet, which connected systems via a thick coaxial cable, proved difficult to install and maintain. Thin Ethernet, introduced in the mid-1980s, was easier to work with, but each segment supported a limited number of systems.
Twisted pair cables began to replace both thick and thin coaxials in the 1990s and quickly became the most common cable type for 10 Mbps, 100 Mbps and 1 Gbps networks. It is less expensive and much easier to work with than either type of coax. Twisted pair is categorized by its supported data rate. Cat5e and Cat6 cable are widely installed and support up to 1 Gbps of data at a minimum of 100 meters.
Power over Ethernet adds an additional advantage to twisted pair. Power is supplied from the switch to the device through the twisted pair. There's no need to plug remote equipment such as ceiling-mounted wireless access points or surveillance cameras into a wall power outlet.
How Ethernet works
Recent advances in wireless technology have created a problem when it comes to maintaining the best Ethernet networking performance on a network. IEEE 802.11n offered a maximum data rate of 600 Mbps so a 1 Gigabit Ethernet (GbE) link to the switch was adequate. The problem comes with IEEE 802.11ac, which builds on features introduced in 802.11 to offer maximum data rates in excess of 1 Gbps.
The new standard is being released in two waves. The Wave 1 standard was finalized in early 2014, and products have been available for several years. Wave 1 products support up to four multiple input multiple output (MIMO) streams, as did 802.11n, but they provide increased throughput by using a wider radio channel width and a more efficient modulation method.
Wave 1 products can reach a theoretical maximum data rate of 1.3 Gbps, but, as with all wireless products, actual observed throughput is lower. As a result, a 1 Gbps Cat5e or Cat6 twisted pair link to the switch is adequate in most cases.
The Wave 2 standard adds features that further increase throughput. It doubles the number of MIMO streams to eight and doubles the channel width compared to Wave 1. Wave 2 also introduces multiple user MIMO. This feature permits an access point (AP) to communicate with up to four devices at the same time. All of these capabilities increase potential throughput beyond 5 Gbps.
Most APs will never exhibit this rate, but throughput exceeding the capacity of a 1 Gbps link is expected. While 10 GbE has been available since 2002, it does not operate over the Cat5e or Cat6 cable typically used to connect switches to APs. Upgrading to 10 GbE requires replacing existing cable with Cat6a or with fiber or twinax cable -- an expensive and disruptive effort, since replacing a single cable usually means replacing the entire bundle.
Features to look for
Network equipment vendors have proposed an alternative to the above: a new standard for 2.5 GbE and 5 GbE over existing Cat5e or Cat6 cable. Two industry alliances, MGBASE-T and NBASE-T, were formed in 2014. The MGBASE-T Alliance includes Alcatel-Lucent, Aruba, Avaya, Broadcom, Brocade, Extreme and several smaller technology companies. NBASE-T was initiated by Cisco, and semiconductor vendors Aquantia, Freescale and Xilinx. Other vendors subsequently joined, including Intel and MGBASE-T members Aruba, Broadcom and a number of component vendors.
Each alliance submitted proposals, and the IEEE began work in early 2015. Progress has been rapid. The standard draws from technology developed for 10 GbE. Unlike some cases in the past where dueling vendor groups slowed work, representatives from both groups have worked together in the IEEE committee to develop the final spec. A draft was published late in 2015, and work is expected to complete late in 2016. In anticipation, several major switch vendors have introduced products based on the draft.
Aruba, Cisco, Extreme Networks and Ruckus Technologies currently offer Wave 2 products. Some of these products accommodate throughput greater than 1 GbE by including two 1 GbE ports, an acceptable option if another cable and switch port are available. Others include a pre-specification 2.5 GbE or 5 GbE interface. Switch and AP vendors have assured potential customers that any changes to meet the final spec can be done via software.
The bottom line
Potential buyers interested in selecting the most optimal Ethernet networking technology for their particular network should carefully evaluate their requirements before quickly upgrading to IEEE 802.11ac. If more wireless throughput is needed, it's important to determine whether users' phones and laptops support the new standard. If not, upgrading APs won't provide any benefit.
IEEE 802.11ac APs support 802.11n, but don't assume that all 802.11n devices will communicate with an 802.11ac AP, since 802.11ac operates only in the 5 GHz band. However, 802.11n operates in both the 2.4 GHz and 5 GHz bands. Some 802.11n clients can switch between bands, but some older devices are confined to 2.4 GHz. Most 802.11ac APs now on the market contain two radios: one 5 GHz radio and a second 2.4 GHz radio for 802.11n clients. Be sure to select a dual radio AP until all older devices have been replaced.
As with any network upgrade, the equipment will work only as well as the cabling. Experience has shown that cables able to reliably carry 1 Gbps can carry traffic up to 5 Gbps. In any case, testing is worthwhile.
You can test each cable in the bundle using specialized equipment. A less disruptive and time-consuming method is to simply plug in the cable at the AP and switch, and then check switch status to see if the port has successfully connected at 2.5 GbE or 5 GbE. If the switch has auto-negotiated down to 1 GbE, the cable is most likely the problem.
After evaluating the need for capacity, client support and cable quality, move carefully and don't make a snap decision on the best Ethernet networking foundation for your company. It's early in the Wave 2 product cycle. Not all current Wave 2 products include all the capabilities in the IEEE specification. Make sure you are getting the features you need before making a selection.
About the author:
David Jacobs brings more than 30 years of experience managing software projects for technology firms and writing on technical subjects. He has held a succession of product development management positions encompassing both software and hardware organizations. Products included the basic TCP/IP stack for a proprietary operating system, both low- and high-end switches and routers, and network applications such as DHCP and DNS. Target markets ranged from small and medium enterprises to telecom providers. A graduate of MIT, Jacobs received an MBA from Boston University. He is based in the Boston area.
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