Wireless Transmission – The importance of SDN for simpler management

Regarding bandwidth, Wide Area Network (WAN) traffic doubles every two years, with service flows now exceeding 1Gbps while aggregate traffic between sites may reach 100s of Gbps.

This traffic is handled by multiple transmission technologies that include optical, packet optical but also wireless.

 

The traffic pattern challenge

Bandwidth is now consumed in a completely different way than 2 or 3 years before. Traffic patterns are seismically shifting mainly due to cloud services and video usage from mobile devices.

Users have access to computers (smartphones) all the time, and they like watching videos on them. Users also prefer self-serve, on-demand infrastructure and applications based on virtualized compute and storage. Therefore, their expectations of the WAN has also changed.

Users expect WAN to support and adapt to this new dynamic technology environment.

But can this be done? What is the situation now?

 

The Current Situation

Current transport networks can not address the challenges of bandwidth growth and unpredictable traffic patterns for two main reasons:

• planning and operation of these networks is separate from the client layers and applications they serve
• realization of connectivity services is lengthy and costly

 

Planning of wireless transmission follows planning of the Radio Access Networks and uses static values for bandwidth and traffic patterns. How much more bandwidth can you reserve for future growth when the traffic patterns are unpredictable?

Realization of connectivity services requires manual intervention and careful planning. Only few operators are maintaining a network services inventory, therefore modification of a service needs careful consideration and verification, as it may lead to network outages.

Additionally, Wireless is rarely the only technology used in transmission networks. A typical transmission network consists of a mix of wireless with optical and packet optical and even SONET/SDH nodes. Therefore planning needs to be multi-technology, multi-vendor, multi-layer and multi-domain.

 

 

Introducing SDN

Lets see if SDN can help address wireless transmission challenges, i.e. if it will enable operators to turn up, modify and tear down communication services in near real time.

 

The SDN Principles

Software Defined Networking (SDN) was invented to apply three principles on packet forwarding among packet switches. The principles are:

• Open refers to usage of open-source instead of closed source protocols and technologies. In the SDN case, the open protocols are OpenFlow and Rest APIs.
• Application-driven refers to the capability of business applications to control in near real-time the turn up, modification and tear down of end user services.
• Programmatic refers to the capability to control the networks through software functionality. This functionality can be provided by vendors or operators but the important point is that it can make the configuration and re-configuration of networks automatic. This is similar to cloud services, that when ordered are realized in real-time without any manual intervention.

 

The SDN architecture

Principles are good, but how can they help us solve our bandwidth and traffic patterns problems?

SDN realization requires a new architecture that has been designed to enable more agile and cost-effective networks. The SDN architecture according to Open Networking Foundation (ONF) consists of three layers, which are distinct and accessible through open APIs.

• The Application Layer, consisting of applications that “consume” the communication services.
• The Control Layer, providing the logically centralized control functionality that supervises the network through an open interface.
• The Infrastructure Layer, consisting of the Network Elements (NEs) and devices that are controlled through SDN.

According to ONF, the infrastructure layer consists of packet switches, performing switching and forwarding.

And the question arises: what will be the benefits in case we use SDN to control wireless transmission? Will we achieve the agility and flexibility needed?

 

The SDN promise

The principles and architecture of SDN come to help us support the highly dynamic transmission network environment by allowing us to turn up, modify and tear down network services in near real time. But how can this be achieved?

SDN is characterized by the following key attributes:

• Logically centralized intelligence
• Programmability
• Abstraction

These key attributes bring these benefits. Lets take a closer look.

 

Attributes and Benefits of SDN

Logically Centralized Intelligence

By having centralized intelligence instead of distributed autonomous systems, we enable client layers and applications to take decisions based on a global (or domain) view of the network.

This attribute has many benefits, as it allows applications via Rest APIs or Openflow to remotely configure and re-configure the network, i.e. turn up, modify and tear down communication services based on the domain view of the network.

Programmability

Programmability is the capability to allow software to control the behaviour of the network. Programmability has important benefits and the biggest one is that it allows vendors and operators to automate network configuration, to happen in response to bandwidth demand or traffic patterns.
This automation capability will allow operators to differentiate and innovate.

 

Abstraction

With SDN, the applications that consume the communication services are abstracted, or decoupled from the underlying network technologies. In the same manner, network devices are also abstracted or decoupled from the SDN control layer. The benefit? Investments in applications and control software becomes future proof, portable!

And the question arises: can we use SDN to control wireless transmission to achieve the agility and flexibility needed?

 

Implementing SDN in Wireless Transmission

Extending the Standards

SDN and specifically the OpenFlow standard needs to be extended in order to support wireless transport networks. Until recently, the OpenFlow standard focused on the packet-oriented Layers 2 and 3.

Multiple standard bodies like ONF, OIF, ITU-T, BBF and TMF are working to extend OpenFlow to cover domains like Optical Transmission and Radio Access in order to support critical operations, administration and maintenance (OAM) capabilities, such as protection and performance monitoring.

Work is required also to extend OpenFlow for Wireless Transmission. These extensions will be discussed in a following article, together with use cases.

 

What about multi-X networks?

In real life, wireless transmission is just one of the many technologies used in operators transmission networks. These networks tend to be multi-X networks, as they can be multi-technology, multi-vendor, multi-domain and multi-layered. So what can you do in these cases?

The answer here is Orchestration, defined as the capability to manage (i.e. turn up, modify and tear down) communication services over a multi-X network. Orchestration will be discussed in a following article.

 

Conclusion

In the new era of intense competition where technology advances are affecting every day life, bandwidth growth never seems to end and traffic patterns are unpredictable. Operators need therefore their wireless transport networks to become dynamically programmable in order to offer new services and match capacity to traffic demand without over-provisioning. Applying SDN to wireless transmission, will provide the architecture and mechanisms necessary to enable programmatic and dynamic control which will increase operator’s revenue opportunities and operational agility.

 

Discuss with us!

Do you agree that SDN is important for wireless transmission? What are the use cases and Openflow extensions you would like to see in a following article? Use the comments below to give us your opinion.