The benefits of new packet transport backhaul technologies like carrier ethernet have gained relatively widespread acceptance at this point; however, many operators are unsure about how they can make the transition to next-generation backhaul a smooth one. While this uncertainty is slowly diminishing, with mobile backhaul networks representing about a third of an opeartor's costs and new LTE requirements gaining momentum, the need for proficiency in lowest-cost, packet-based backhaul networks is becoming both urgent and inescapable.

In May, the U.S. General Services Administration (GSA) reported that 319 operators worldwide had committed to LTE deployments or trials, up from 248 in October.  Echoing this momentum, wireless industry research firm Marevis recently estimated that by 2016, LTE will account for 97 percent of the industry's 572 million 4G-enabled devices. With the march toward broad 4G adoption well underway, wireless network CAPEX/OPEX dynamics are set to be dramatically impacted.

Below are five key areas that carriers need to understand as they consider and begin the transition to packet-based transport backhaul networks.

1. Complexity vs. Simplicity

In addition to dealing with overall raw capacity increases and new, connection-oriented consumption patterns, operators need to consider several other key factors as they seek to evolve their networks, including: the level of complexity of the protocol stack they employ, what level of network resiliency features are required, the need for automation for quick service turn-up, and which Ooperations, Administration & Maintenance (OAM) tools are best to efficiently monitor, maintain and troubleshoot the network.

In a mobile backhaul network, there are many end points (macro cells and small cells), with the vast majority of traffic destined for the mobile switching center and beyond. As the number of cell sites in the backhaul network grows, scalability problems are introduced. 

IP/MPLS is frequently used in core networks and is evolving into backhaul, where its control plane functionality adds security, stability, scalability and OPEX concerns under the façade of “unification.” MPLS dynamic label distribution protocols are costly and overly complex for addressing mobile backhaul, which is primarily a packet transport issue.  It is better suited for the core where there are a smaller number of nodes with a higher volume of traffic and greater mesh requirements.

Arguing for a consistent, single technology domain in both the core and backhaul is like arguing that semi-trucks are ideal for both intercity highway transport and congested urban transport of goods. The semi-truck solution does not effectively fit the congested urban transport problem, and arguing for a unified solution simply adds complexity and cost to the solution. The problems are very different and require different solutions.

Mobile backhaul connections tend to have longevity, and pre-determined Layer 2 paths are less complex and more scalable than IP/MPLS paths established via a dynamic control, leading to reduced costs. Packet technologies like Carrier Ethernet or MPLS-TP exceed the technical requirements while reducing the complexity of the solution.

2. Cost, Cost, Cost

A key benefit of using the right packet infrastructure is that it reduces backhaul costs without sacrificing functionality. An ideal packet transport solution can deal effectively with network requirements like OAM, latency, synchronization, and automated provisioning. And, as many seasoned operators have learned, there are huge OPEX advantages associated with backhaul solutions that are specifically tailored to solve the backhaul problem.

Carrier Ethernet has proven to be the most cost-effective solution in meeting current and future mobile backhaul requirements. This includes higher capacities, lower latency, flexible network topologies (e.g. hub-and-spoke, ring, mesh), resiliency (quick, predictable failover), the need to operate 2G, 3G, and LTE on the same backhaul network, automated provisioning and lower CAPEX and OPEX.  At Ciena in particular, we’ve seen Carrier Ethernet customers realize savings of up to 30 percent in both CAPEX and OPEX, compared with the costs of using Layer 3 backhaul solutions.

3. Network Quality

Packet Transport solutions like Carrier Ethernet or MPLS-TP change the backhaul game in terms of scalability, reliability and QoS. They enable providers to cost-effectively scale to extremely high capacity, and in granular increments. They also provide more flexibility, resiliency and protection mechanisms that simplify provisioning and ongoing maintenance efforts, reducing operations costs. Finally, better QoS controls provide predictable service delivery.

A quality Carrier Ethernet solution will deliver much higher levels of service classification, enabling rich service stratification to reach a broader range of customers and increase revenues.  Rather than designing backhaul networks to peak rate capacities, robust QoS and traffic shaping capabilities make better incremental use of bandwidth, improving both the scale and costs of backhaul network solutions.

4. Operations, Administration & Maintenance

As operators move toward packet backhaul, OAM capabilities are a key area of consideration. Robust OAM is essential to successful packet transport backhaul since it allows operators to quickly and reliably detect, verify and isolate Ethernet connection failures, and to ensure predictable and rapid recovery. Operators should look at key functional areas, such as Connectivity Fault Management (CFM), Ethernet in the First Mile (EFM), Link Layer Discovery Protocol (LLDP) and performance monitoring for delay, jitter and packet loss, as well as performance benchmarking.

Having the right OAM tools to isolate, diagnose and fix problems improves responsiveness, minimizes network downtime, helps avoid truck rolls, and reduces overall OPEX.  The Layer 2 OAM tools not only facilitate network independent service delivery, but they also offer superior visibility, manageability, and control.

5. Multiple Applications, One Backhaul Network

As part of the move to high-speed 4G networks, wholesale operators are looking to quickly and cost-effectively support and deliver a range of new high-speed, revenue-generating services from the same converged packet transport network. With the right supplier and the right technology solution, Ethernet Business Services can be strategically rolled out from the same infrastructure where backhaul services are offered. The right packet transport technology can facilitate the service turn up and modification on demand. Flexibility becomes critical in allowing operators to accelerate and automate service creation and activation – ultimately bringing differentiated multi-application services to market faster and also significantly reducing time to revenue.

Easing the Transition

As the march toward pervasive 4G networks intensifies, more operators are becoming aware of the cost, efficiency, performance, and overall business benefits that Layer 2 packet transport backhaul provides. However, the next step in the evolution to 4G backhaul is for these operators to continue to gain increased comfort levels with packet transport technologies like MEF Carrier Ethernet and MPLS-TP and to clearly understand the key considerations for a seamless transition.

Andy Walker is Director of Portfolio Solutions at Ciena.