Planning the supercharged future of Ethernet: Four new speeds are in the works
By Stephen Lawson
Ethernet’s future is now about much more than the next top speed: The engineers charting a path for the ubiquitous networking protocol are looking at several new versions to serve a variety of applications.
At a meeting last Thursday of the Ethernet Alliance, an industry group that promotes IEEE Ethernet standards, three major new projects were up for discussion.
To meet immediate demands in cloud data centers, there’s a standard in the works for 25Gbps (bits per second). For the kinds of traffic expected in those clouds a few years from now, experts are already discussing a 50Gbps specification. And for enterprises with new, fast Wi-Fi access points, there may soon be 2.5Gbps Ethernet. That’s in addition to the next top speed for carrier backbones and moves to adapt the technology for use in cars.
These efforts are all meant to serve a growing demand for Ethernet outside the traditional enterprise LANs for which it was originally designed. That means solving multiple problems instead of just how to get ever more bits onto a fiber or copper wire.
“What I’m hearing is lots of diversity. Lots of diversity in need, lots of diversity for the future,” Ethernet Alliance Chair John D’Ambrosia said part way into the daylong meeting in Santa Clara, California. “We’re moving away from an ‘ethernet everywhere’ with essentially the same sort of flavor.”
The EA’s annual Technology Exploration Forum is a venue for discussing the kinds of technical details that many participants will go on to debate in various task groups of the IEEE 802.3 Working Group, which sets the official standards for ethernet. Optical and electrical signaling, fiber strands and copper wires, processing power, energy consumption, heat, cost, and other issues all come into play in determining what to build and how.
What’s coming for Ethernet
Without diving too deep into those details, here are some of the new technologies brewing in Ethernet.
A 25Gbps standard may seem like a step backward, because 40-Gigabit and 100-Gigabit Ethernet already exist. But in fact, it’s all about the need for more speed, specifically from servers in cloud data centers. Google and Microsoft are the biggest buyers of Ethernet now, largely because their cloud operations require so much data exchange between servers, according to Dell’Oro Group analyst Alan Weckel.
The key to 25-Gigabit Ethernet is that many of the components that could go into it are already developed: The 100-Gigabit standard is made up of four “lanes” of 25Gbps, so many of the same parts go into that high-end gear. That should mean higher production volumes for parts that go into both technologies, driving prices down.
Rallying around 25Gbps also gives network architects a logical way to build their data centers, with servers linking to switches at 25Gbps and the switches aggregating those connections into 100-Gigabit uplinks, Weckel said. That four-to-one ratio is what they’re used to working with.
Having building blocks in multiples of 25 will become more important as cloud data centers age, Weckel said. It should let network engineers reuse technology as needs and speeds grow.
“Right now, all clouds are greenfield, but as the cloud matures, and actually has a real business model and has to actually talk to Wall Street and explain the billions of dollars that they spend on every data center, you’re going to see reuse become very important,” Weckel said.
By contrast, 40-Gigabit Ethernet is made up of four lanes of 10-Gigabit Ethernet, a technology that the cloud giants are now outgrowing, Ethernet Alliance’s D’Ambrosia said. They need more than 10Gbps for each server, even as average enterprises start to connect more servers at that speed.
Google, Microsoft and several prominent networking vendors formed a group in early July to promote standardization of 25Gbps and 50Gbps Ethernet, saying they couldn’t wait for the IEEE to finish a standard. Later that month, the IEEE started its own 25Gbps task group and said it might be done in as little as 18 months. On Thursday, D’Ambrosia said he doesn’t necessarily agree with that forecast but he’s optimistic. “Consensus is forming quickly in the industry,” he said.
Work is also beginning on a 50Gbps specification, which could be the next speed offered for linking servers in data centers. Both servers and high-performance flash storage systems will drive a need for something more than 25Gbps in the biggest data centers in a few years, Weckel of Dell’Oro said.
At Thursday’s event, attendees debated whether to seek a 50Gbps standard or go all the way to a single-lane system for 100Gbps. A 50Gbps specification is more within reach, said Chris Cole, director of transceiver engineering at Finisar. For a 100Gbps standard today, “you’re pushing the components,” Cole said. He expects to see standard 50Gbps products starting in 2016.
It may not sound very fast, but 2.5-Gigabit Ethernet might help companies fill their buildings with very fast Wi-Fi. It’s being proposed specifically as a tool to help enterprises’ wired infrastructure keep up with wireless access points that increasingly form the edge of those networks.
The latest Wi-Fi technology, IEEE 802.11ac, can operate at more than 1Gbps—much more, with certain configurations. With that much traffic going over the air, the Gigabit ethernet links that most enterprises use to connect their access points to the wired network could become a bottleneck, said Kamal Dalmia, vice president of sales and marketing at Aquantia.
Upgrading to 10-Gigabit Ethernet would give networks plenty of bandwidth, but most companies don’t have the right kind of cable to do that, Dalmia and other participants said. A 2.5Gbps version of Ethernet would work on commonly used Category 5e and Category 6 cable over the standard distance of 100 meters, so users could go beyond Gigabit ethernet without the cost of pulling new cable.
Aquantia is already producing silicon for ethernet gear that can run at 2.5Gbps or 5Gbps. The process of setting a 2.5Gbps Ethernet standard, which might also involve 5Gbps capability, is expected to begin at an IEEE meeting next month.
Ethernet’s backers haven’t given up on reaching a new top speed, either. An IEEE task group is already working on a 400-Gigabit ethernet standard, which is currently projected for completion in March 2017. The fast links might use multiple lanes of either 50Gbps or 100Gbps. Once finished, the superfast technology would be destined for the cores of service-provider networks.
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