GETTING IN SYNC

Although vendors have devised multiple ways to deliver carrier Ethernet for wireless backhaul, no single solution stands out to consultants or analysts as the best way to go about it.

“Vendors have competing schemes, and we have yet to see how they pan out,” Celentano said. “Once we get more carrier Ethernet in the networks, we will know how well it works, but right now vendors are mostly still in trials. It is easy to claim success in trials and small deployments, but when you scale it to hundreds of thousands of cell sites, will it work?”

Analysts do agree, however, that two things need to happen for any of the carrier Ethernet solutions to work: standards and synchronization. On the standards side, the Metro Ethernet Forum has developed technical specifications and implementation agreements to promote interoperability and deployment of carrier Ethernet worldwide. At CTIA Wireless 2008, the MEF conducted a public multivendor mobile backhaul interoperability test that simulated an integrated, multiservice, next-generation core, aggregation and access network supporting high-quality mobile backhaul services.

“In the lab, we see quite good results in all our tests and feel that carrier Ethernet for mobile backhaul will work up to MEF standards,” said Carsten Rossenhoevel, managing director of the MEF's European Advanced Networking Test Center. “After testing 85 devices from 15 companies, we are confident that the industry is getting there.”

There was big news at CTIA on the timing and synchronization side, as well. Symmetricom unveiled its network synchronization and timing solution, the TimeProvider 5000 IEEE 1588v2 Grandmaster clock, which makes the rocky road to Ethernet much easier to navigate. The device is based on IEEE 1588, or PTP — a protocol that enables accurate distribution of time and frequency over packet-based networks. PTP employs hardware-based time-stamping to synchronize all real-time clocks distributed throughout the packet network.

AN EMERGING MARKET

So if carrier Ethernet is such an ideal solution for wireless backhaul, where can we find it today? Although interest certainly is prevalent among carriers, live deployments specifically for wireless backhaul are hard to find. Most vendors can only speak to success in the lab so far.

Despite the successful interoperability test, the MEF's Rossenhoevel admitted that issues such as jitter still exist in live networks, and more research needs to be done. He acknowledged that many carriers already are testing carrier Ethernet for wireless backhaul in their labs, and he expects to see U.S. deployments in about two years.

Mike Vizzi, product manager for Symmetricom, agreed with that time frame. In April, more than a dozen service providers and equipment manufacturers began stringent lab testing of Symmetricom's Time Provider 5000 IEEE 1588v2 Grandmaster.

“We expect general availability and volume production in August, with major deployments to start in the first half of next year,” Vizzi said.

Both Rossenhoevel and Vizzi noted that once carrier Ethernet catches on as the leading mobile backhaul technology, it will still take years for service providers to completely upgrade their networks from TDM-over-T-1s.

“Migrating from T-1s to carrier Ethernet for mobile backhaul is not a simple rollout that is done in a few months,” Rossenhoevel said. He expects the migration to take around five years.

The reality is that service providers have thousands of remote base stations, Vizzi added. From a pure logistics standpoint, migration will not happen overnight but over a period of years.

“Some carriers might decide to leave parts of their network just the way they are, while in other areas they need to upgrade to carrier Ethernet quickly because they are experiencing explosive growth with a lot of traffic and new applications,” Vizzi said.

Errol Binda, senior product marketing manager for the metro Ethernet networks group for Nortel Networks, said Nortel has several ongoing lab trials and actual deployments in Europe and the U.S. At this time, however, the company is unable to name its customers.

“Migration will be a gradual process,” Binda said. “The solution could be different in different markets or even different regions.”

CASE STUDY: IMPLEMENTING CARRIER ETHERNET

When M3 Wireless of Hamilton, Bermuda, began offering wireless Internet services in 2006, it sought a backhaul solution that would provide more bandwidth and higher speeds to support growing data usage.

“One solution was fiber, but leasing fiber from another company would be costly,” said Kevin Jackson, wireless network manager for M3. “Carrier Ethernet provided the most bang for the buck.”

After a diligent research process, the carrier decided to go with wireless microwave for backhaul. Jackson contacted DragonWave, a provider of high-capacity wireless Ethernet equipment that offers a licensed product in the 13 GHz spectrum for which M3 holds a license. The AirPair radio platform featured several benefits that appealed to Jackson, including rapid link shutdown (RLS). This patent-protected feature detects error conditions when carriers use the spanning tree protocol in an Ethernet ring. Spanning tree is a link management protocol that provides path redundancy while preventing undesirable loops in the network.

“RLS gives you the option to detect error conditions on the link, and if it hits a certain threshold, it will shut down,” Jackson said. “With Ethernet shutting down, it allows spanning tree to converge properly. From experience, I have learned how devastating it could be without a feature such as RLS in an Ethernet ring.”