OIF defines carrier requirements for SDN
The Optical Internetworking Forum (OIF) has achieved its first milestone in defining the carrier requirements for software-defined networking (SDN).
The orchestration layer will coordinate the data centre and transport network activities and give easy access to new applications
Hans-Martin Foisel, OIF
The OIF's Carrier Working Group has begun the next stage, a framework document, to identify missing functionalities required to fulfill the carriers' SDN requirements. "The framework document should define the gaps we have to bridge with new specifications," says Hans-Martin Foisel of Deutsche Telekom, and chair of the OIF working group.
There are three main reasons why operators are interested in SDN, says Foisel. SDN offers a way for carriers to optimise their networks more comprehensively than before; not just the network but also processing and storage within the data centre.
"IP-based services and networks are making intensive use of applications and functionalities residing in the data centre - they are determining our traffic matrix," says Foisel. The data centre and transport network need to be coordinated and SDN can determine how best to distribute processing, storage and networking functionality, he says.
SDN also promises to simplify operators' operational support systems (OSS) software, and separate the network's management, control and data planes to achieve new efficiencies.
SDN architecture
The OIF's focus is on Transport SDN, involving the management, control and data plane layers of the network. Also included is an orchestration layer that will sit above the data centre and transport network, overseeing the two domains. Applications then reside on top of the orchestration layer, communicating with it and the underlying infrastructure via a programmable interface.
"Aligning the thinking among different people is quite an educational exercise, and we will have to get to a new understanding"
"The orchestration layer will coordinate the data centre and transport network activities and give, northbound, easy access to new applications," says Foisel.
A key SDN concept is programmability and application awareness, he says. The orchestration layer will require specified interfaces to ease the adding of applications independent of whether they impact the data centre, transport network or both.
Foisel says the OIF work has already highlighted the breadth of vision within the industry regarding how SDN should look. "Aligning the thinking among different people is quite an educational exercise, and we will have to get to a new understanding," he says.
Having equipment prototypes is also helping in understanding SDN. "Implementations that show part of this big picture - it is doable, it is working and how it is working - is quite helpful," says Foisel.
The OIF Carrier Working Group is working closely with the Open Networking Foundation's (ONF) Optical Transport Working Group to ensure that the two group are aligned. The ONF's Optical Transport Group is developing optical extensions to the OpenFlow standard.
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