As I've consistently highlighted over the last few years, there has been a very substantial gap between the deployment of "Ethernet-ready" backhaul equipment in the network and the turning up of that capability to live commercial service. What some were calling a "backhaul boom" in 2007 and 2008 was certainly a boom in vendor shipments and market hype. But when you talked at the time to the operations directors in the carriers charged with making Ethernet backhaul actually work, the only "boom" they could identify was the sound that a firearm might make if it just happened to be discharged in the direction of the vendors who told them how quickly this terrific new kit was going to reduce their costs.

This delta between initial trial deployment and large-scale service activation lasted as much as three years in some cases, as operators grappled with the decidedly non-trivial technological and operational challenges of rolling out a packet service between their cell sites and their RNCs or BSCs. Architectures, protocol selections and vendors were often selected, only for the strategy to be scrapped six months down the road and completely rethought from first principles.

A lot later than some of my clients would have liked, I'm happy to be able to look back on 2010 as the year when Ethernet backhaul fully exited the trial and tactical deployment phase and was turned up to commercial service in mass-market volumes by some of the world's leading operators. As Nicki Palmer, VP of network operations support at Verizon Wireless , told Light Reading's "Backhaul & Core Convergence Strategies" event at 4G World in Chicago last October, "18 months ago I was losing sleep over Ethernet backhaul, but I'm not losing sleep anymore."

Much the same could be said of other leaders such as BT Group plc (NYSE: BT; London: BTA), some of Deutsche Telekom AG (NYSE: DT)'s European subsidiaries and quite a few operators in emerging markets that are "leapfrogging" to Ethernet backhaul off the back of new generations of Ethernet-ready 3G base stations deployed from the launch of 3G service.

Precisely because of the pain that had to be got through to get there, the large-scale rollouts of 2010 have been remarkable. In some cases, it wouldn't be an exaggeration to call them "epic." Some networks have undertaken a complete refresh of their 2G and 3G base stations and their backhaul equipment with fiber, Ethernet microwave, cell site switches and routers, optical and assorted other equipment types.

In the latest iteration of Heavy Reading's Ethernet Backhaul Quarterly Market Tracker, we forecast that 16 percent of the world's cell sites will have Ethernet backhaul in live service by the end of 2011. For the time being, the hybrid model – whereby voice continues to be carried over E1s/DS1s, while high speed data is carried over Ethernet – is still the preferred model, as cautious carriers continue to outnumber those that are more IP-savvy. But recent Heavy Reading survey data also shows that sentiment is starting to turn here, with carriers becoming increasingly confident about carrying voice over packet in the backhaul.

We forecast that three quarters of the world's cell sites will have packet backhaul in live service by the end of 2015, with the presence of TDM in the network very much on the way out by then. Is there a show-stopper? Not as such, but there's a show-slower, if I can coin such an ugly term. And that's the old bugbear of network timing or synchronization: Once you remove E1s or DS1s altogether from the cell site, you'd better have an alternative timing or synchronization solution in place if you don't want your service quality to deteriorate some weeks or even days later. Most operators that have packet backhaul in service are still leaving a DS1 or E1 at the cell site – if not to carry voice service, then at least for synchronization. That can't continue if the full cost savings of Ethernet backhaul are to be realized. And in the pain that has already been gone through – and that many operators outside the leading pack still continue to go through – mastering the cost or implementation challenges of new synchronization standards such as Synchronous Ethernet and IEEE 1588v2 has been one of the sorest points.

It's therefore good to see the individual efforts that vendors such as Alcatel-Lucent (NYSE: ALU), Cisco Systems Inc. (Nasdaq: CSCO) and Huawei Technologies Co. Ltd. have been making to demonstrate their proof points on the 1588v2 standard, which is by far the trickier of the two from an implementation standpoint. It's also been good to see multi-vendor collaboration by Accedian , Alcatel-Lucent, Anue Systems Inc. , Brilliant Telecommunications Inc. , Calnex Solutions Ltd. , Chronos Technology Ltd. , Ericsson AB (Nasdaq: ERIC), Huawei, Iometrix Inc. and Symmetricom Inc. (Nasdaq: SYMM) in announcing the formation of the IEEE 1588v2 Conformity Alliance. This is serving to certify vendor conformity to the standard, rather than simple interoperability.

It's also good to see Symmetricom's SyncWorld ecosystem announcement at CTIA , whereby multiple backhaul vendor partners have agreed to provide detailed blueprints for operators on exactly how to deploy their products to ensure optimal performance of the 1588v2 standard. Alcatel-Lucent, Cisco and Nokia Networks were named as Strategic Partners in SyncWorld, while Aviat Networks Inc. (Nasdaq: AVNW), Brocade Communications Systems Inc. (Nasdaq: BRCD), Ciena Corp. (NYSE: CIEN), Extreme Networks Inc. (Nasdaq: EXTR), PMC-Sierra Inc. (Nasdaq: PMCS), RAD Data Communications Ltd. and Telco Systems (BATM) were named as Interoperability partners.

Up ahead, some very thorny new backhaul dilemmas are starting to emerge. When (if ever) will the X2 interface be needed for LTE backhaul? When (if ever) will phase synchronization be needed with FDD-based LTE networks? And when (if ever) will IPsec be needed in conjunction with LTE backhaul? Those questions are for carriers to resolve by the time of the next summit on this challenging roadmap. For now, the leaders among the carriers can pause and enjoy the view from this one. And congratulate themselves on a job well done – at least for now.

— Patrick Donegan, Senior Analyst, Wireless, Heavy Reading