Stu Elby, the Chief Technologist at Verizon, has been evangelizing how SDN will help create service aware networks, and how a use case such as service chaining can be one of the early applications for SDN within the WAN. There is a video on YouTube http://www.youtube.com/watch?v=M15h0ik9i7g where he and Joe Constantine, the CTO of Sales for the Americas at Ericsson, are interviewed by Martin Taylor, the CTO of Metaswitch. They are both in agreement that this use case provides key merit and many benefits. Stu explains how today Verizon offers a large range of services that are consumed by the mass market, all of which currently run over the IP network. As the network operates today, it is very costly because these services are stitched at the IP layer in static fashion and go through many appliances, firewalls, screening devices, and other value-added devices, whether the customer signed up for it or not, because the network is architected via source and destination routing.
He sees SDN as a mechanism to provide service aware routing, which includes traffic steering and global load balancing, and will enable not only the information in the packet but the subscription of the user and what type of service is coming over the network(e.g. a YouTube click or a SIP call). All of this information will be taken into account and packets will be moved through the network more efficiently as the intelligence will be there to know how to connect through certain appliances and skip others based on policies and QoS. Essentially, this entails tying the individual subscriber information accessing the service, like user profiles and network policies, with the static information that already comes through the network to the information in the packet header.
They both feel that there are some key benefits, the first of which is adding value to the customer experience, as well as equipment savings, and CPU savings. Stu further goes on to say that this service can be run as an overlay to an existing IP network using the SDN framework with or without OpenFlow -- however he sees OpenFlow providing additional efficiency as a software-enabled architecture.
These thoughts fit very well into the Brocade vision of using SDN and OpenFlow as an overlay network, and this example should be highlighted as well as the benefits that it will provide within the WAN.