The role of software-defined networking for telcos

The OIF's Carrier Working Group is assessing how software-defined networking (SDN) will impact transport. Hans-Martin Foisel, chair of the OIF working group, explains SDN's  importance for operators.

Briefing: Software-defined networking

Part 1: Operator interest in SDN

"Using SDN use cases, we are trying to derive whether the transport network is ready or if there is some missing functionality"

Hans-Martin Foisel, OIF

Hans-Martin Foisel, of Deutsche Telekom and chair of the OIF Carrier Working Group, says SDN is of great interest to operators that view the emerging technology as a way of optimising all-IP networks that increasingly make use of data centres.

"Software-defined networking is an approach for optimising the network in a much larger sense than in the past," says Foisel whose OIF working group is tasked with determining how SDN's requirements will impact the transport network.

Network optimisation remains an ongoing process for operators. Work continues to improve the interworking between the network's layers to gain efficiencies and reduce operating costs (see Cisco Systems' intelligent light).

With SDN, the scope is far broader. "It [SDN] is optimising the network in terms of processing, storage and transport," says Foisel. SDN takes the data centre environment and includes it as part of the overall optimisation. For example, content allocation becomes a new parameter for network optimisation.

Other reasons for operator interest in SDN, says Foisel, include optimising operation support systems (OSS) software, and the characteristic most commonly associated with SDN, making more efficient use of the network's switches and routers.

"A lot of carriers are struggling with their OSSes - these are quite complex beasts," he says. "With data centres involved, you now have a chance to simplify your IT as all carriers are struggling with their IT."

The Network Functions Virtualisation (NFV) industry specification group is a carrier-led initiative set up in January by the European Telecommunications Standards Institute (ETSI). The group is tasked with optimising software components, the OSSes, involved for processing, storage and transport.

The initiative aims to make use of standard servers, storage and Ethernet switches to reduce the varied equipment making up current carrier networks to improve service innovation and reduce the operators' capital and operational expenditure.

The NFV and SDN are separate developments that will benefit each other. The ETSI group will develop requirements and architecture specifications for the hardware and software infrastructure needed for the virtualized functions, as well as guidelines for developing network functions.

The third reason for operator interest in SDN - separating management, control and data planes - promises greater efficiencies, enabling network segmentation irrespective of the switch and router deployments. This allows flexible use the network, with resources shifted based on particular user requirements.

"Optimising the network as a whole - including the data centre services and applications - is a concept, a big architecture," says Foisel. "OpenFlow and the separation of data, management and control planes are tools to achieve them."

OpenFlow is an open standard implementation of the SDN concept. The OpenFlow protocol is being developed by the Open Networking Foundation, an industry body that includes Google, Facebook and Microsoft, telecom operators Verizon, NTT, Deutsche Telekom, and various equipment makers.

Transport SDN 

The OIF Working Group will identify how SDN impacts the transport network including layers one and two, networking platforms and even components. By undertaking this work, the operators' goal is to make SDN "carrier-grade'.

Foisel admits that the working group does not yet know whether the transport layer will be impacted by SDN. To answer the question, SDN applications will be used to identify required transport SDN functionalities. Once identified, a set of requirements will be drafted. 

"Using SDN use cases, we are trying to derive whether the transport network is ready or if there is some missing functionality," says Foisel.

The work will also highlight any areas that require standardisation, for the OIF and for other standards bodies, to ensure future SDN interworking between vendors' solutions. The OIF expects to have a first draft of the requirements by July 2013.

"In the transport network we are pushed by the mobile operators but also by the over-the-top applications to be faster and be more application-aware," says Foisel. "With SDN we have a chance to do so." 

Part 2: Hardware for SDN