802.11ac Wave 2 & The Multi-Gigabit Ethernet Push

When Cisco launched its multi-gigabit Ethernet technology to support faster WiFi access points last month, it did so without a lot of fanfare. The technology, which Cisco rolled out across several switches, is designed to accommodate 802.11ac Wave 2 gear without the need for new cabling.

The low-key rollout -- at least for Cisco -- comes as two different groups develop standards for 2.5 Gbps and 5 Gbps Ethernet. Cisco, along with Aquantia, Freescale and Xilinx, launched NBASE-T Alliance last October.  Meanwhile, another group that includes Aruba Networks, Avaya, and Broadcom formed the MGBASE-T Alliance.

With 802.11ac Wave 2 products beginning to hit the market and with 802.11ax in the future, enterprises need to prepare for a jump in wireless bandwidth, Cisco and other vendors say. Wave 2 access points will need more than the 1 Gbps Ethernet connections Wave 1 and older generation 802.11n devices used. Using 10 Gbps Ethernet would require an expensive cabling upgrade to Cat 6E, while 2.5 Gbps and 5 Gbps Ethernet ports fill a gap and allow enterprises to use their existing Cat 5E/Cat 6 cabling, they say.

The NBASE-T and MGBASE-T alliances both see 11ac as a major market transition that needs to be addressed. They have the same objectives, but different implementations, Hasan Siraj, senior director of product management for campus switching at Cisco, said in an interview. "The goal is that we come together, and as we go to IEEE, get consensus and arrive at a standard," he said.

Cisco Catalyst multi-gigabit technology

Clearly, Cisco is betting that the eventual consensus will be at least close to the multi-gigabit technology it introduced last month across several of its campus switches.

The new multi-gigabit Catalyst 3840 can be added as a stack member to existing 3840s, which are converged wired and wireless switches. Cisco released a multi-gigabit line card for its Catalyst 4500E converged wired and wireless switch, and released the 3560-CX and 2960-CX as additions to its compact wired switch line. The multi-gigabit technology supports power over Ethernet.

"We are future-proofing customers for a few generations of wireless standards," Siraj said.

Lee Badman, a network engineer and wireless technical lead for a large private university and a Network Computing contributor, said he's pleased with the multi-gigabit concept because it "can address a lot of the challenges that 10 gig is overkill on." He added, "It's a bit of a bummer that, as usual, we see the market leader versus the rest of the pack on a potential new standard."

Jumping the gun?

At the same time, some wireless experts say 802.11ac Wave 2 doesn't require multi-gigabit backhaul links.

"Industry claims of throughput capabilities exceed[ing] 1 Gbps are correct from a theoretical standpoint. However, real-world client mixes on almost every WLAN will mean that backhaul never approaches even close to 1 Gbps of throughput," Andrew von Nagy, a senior WiFi architect, wrote on his blog, Revolution Wi-Fi.

He advised customers only consider greater than 1 Gbps backhaul with Wave 2 in "very specific locations that have a low-density of high-end devices with very demanding bandwidth needs."

In an interview, von Nagy said he wasn't bothered by the dueling 2.5/5 Gbps standards efforts. "The purpose of going through the standards process is to get everyone on the same page," he said.

However, the fact that vendors are pushing multi-gigabit for 11ac Wave 2 illustrates how marketing differs from what's actually needed in customer networks, he said. "If a vendor said, 'You probably don't need this today, but you should be planning ahead,' I'd be fine with that, but it's not going to sell boxes...This is just another driver to increase the speed at which organizations lifecycle their switching hardware," he said.

Long term, there's definitely a need for multi-gigabit at the access layer, von Nagy said, but he cautions customers against making a big hardware investment before a standard is formed; otherwise, they may run the risk of it being incompatible.

Badman said he generally agrees with those who say 1 Gbps is enough to support 11ac Wave 2, but added that 1 Gbps for higher-end 11ac works "against other industry trends of allowing lots of headroom for traffic spikes and surges and future-proofing."

"Some of us have to cable for 10 years or longer, and I like the thought of maximizing the investment in UTP and associated pathway costs," he added.