What is Multiprotocol Label Switching in LTE?

13 May 2011 |


Multiprotocol Label Switching (MPLS) is a technology used to direct and carry data from one network node to another with the help of labels.

Many service providers deploy MPLS to ensure connection availability between two endpoints with quality of service (Qos) guaranteed by a service level agreement (SLA).

What are the benefits of using MPLS in LTE?

Since the world’s first commercial LTE service was launched in December 2009, the pace of LTE adoption has continued to increase rapidly. It is expected to continue, with analyst firm Ovum predicting that the number of LTE connections worldwide is estimated to grow to approximately 346 million by 2015.

As service providers migrate to LTE-based RAN and Ethernet-based packet backhaul networks, they gain the ability to offer mobile data capacities comparable to broadband technologies. The resulting 4G network therefore enables service providers to offer new data intensive services at a low cost per bit, but there is a need to deliver these new services while making optimal use of the network and guaranteeing SLAs from any one point in the network to another.

MPLS has already played an important role in solving similar problems in packet-based core networks. The technology unifies various types of backhaul traffic and offers several migration choices to service providers.

How can service providers deploy MPLS in LTE?

Mobile backhaul networks consist of two segments: access and aggregation segments. Ethernet technologies can be deployed in the access segment, while MPLS can be deployed in the aggregation segment.

Using voice services as an example, service providers require quality assurance during the transition to packet-based backhaul. According to a report from the Broadband Forum, existing packet backhaul deployments use a hybrid approach where voice traffic is carried over TDM and data over packet. Such an approach is expected to dominate packet backhaul deployments in the short to medium future as it also enables service providers to utilise existing infrastructure. MPLS pseudowires (an emulation of a layer 2 point-to-point connection-oriented service over a packet-switching network) provide the ability to aggregate TDM voice and packet data over a common network infrastructure and these are widely deployed in the aggregation parts of mobile backhaul networks as a traffic unifying technology for various RAN types. The forum believes that pseudowire technology is expected to grow rapidly through 2013.

In the case of converged deployments – where both mobile and fixed subscribers share the same network – MPLS can be deployed in both the access and aggregation segments.

As networks continue converging both fixed and mobile services, MPLS is estimated to move further into access networks, at least initially as a transport mechanism to deliver Ethernet services. As additional MPLS transport capabilities are developed, the Broadband Forum believes the adoption of MPLS in mobile backhaul access networks is expected to strengthen.

Why does the industry need to work together in order to make the use of MPLS in LTE successful in the future?

According to the Broadband Forum, it is crucial for mobile operators to consider high-speed packet access evolution and LTE requirements together in the near term in order to optimise backhaul investment and potentially avoid additional upgrade costs in the medium to long term. The forum has identified MPLS as being ‘evolution friendly’ for service providers looking to migrate to a pure packet-based backhaul network.

MPLS features are widely supported by many vendors. These include pseudowires, failure troubleshooting tools and operations, administration and maintenance (OAM). There is, however, a reported lack of commonly agreed frameworks, architectures and deployment scenarios, which the Broadband Forum believes often leads to additional costs when deploying MPLS services. To help avoid this, the forum has set up the MPLS in Mobile Backhaul Initiative (MMBI), which aims to provide a framework and requirements for the use of MPLS technology in mobile backhaul networks. It believes this will help reduce the risks related to interoperability.

The forum has set up a certification programme for vendors which it believes will enable service providers to choose deployment-ready products for their backhaul solutions. It has also proposed a framework for the transport of RAN backhaul traffic over packet-based access, aggregation and core networks. As part of the framework, possible deployment scenarios and recommendations on how to use MPLS in each of the scenarios are provided, acting as a reference guide for vendors and operators.

What role can MPLS play in future networks?

The number and scale of mobile networks will only continue to grow in the future and the Broadband Forum feels there will be a real and apparent need for an end-to-end standards-based solution capable of transporting multiple services.

By introducing a single end-to-end backhaul solution, there could be a reduction in existing operational costs and complexity. MPLS has a proven track record of transporting any service to anywhere and therefore with further investment from vendors and service providers, the technology could play an important role in the future of LTE.