In software-defined networking (SDN), all the talk of fabrics has tended to focus on Layers 2 and 3. F5 has decided its time for Layers 4-7 to get in on the fun, too.

It's a potentially important step for SDN and probably the first of many Layer 4-7 initiatives we'll be seeing in the coming months. As more and more speakers have been saying at SDN conferences, all this SDN stuff is really being done for the sake of what's running at Layer 7, yet the bulk of the technological talk has been at the lower layers.

Being announced Tuesday, F5's new architecture is called Synthesis, and what it produces are software-defined application services (SDAS). It's "the Layer 4-7 overlay fabric sitting on top of an SDN fabric, says Dean Darwin, F5's senior vice president of marketing.

Synthesis dissolves all ADCs into one pool of sharable resources, just as virtualization turned CPU cycles and storage space into unified pools. The idea is to give every application access to a dedicated BIG-IP appliance, which would be expensive in physical form but becomes doable if SDAS resources can be distributed among all the applications.

The SDAS pool is made up of pretty much anything running F5's TMOS architecture: any combination of chassis, appliances, and software. They get pooled together and can be logically carved up into 2,560 virtual BIG-IPs — the maximum number of multi-tenant instances the fabric can handle — with services able to move around the fabric to different hosts as necessary. It's all coordinated at the control-plane level through the company's ScaleN technology.

The fabric can handle a total of 20 Tb/s throughput and 9.2 billion connections, F5 says.

F5 is announcing 11 SDAS reference architectures, covering functions including distributed denial-of-service attacks (DDoS), cloudbursting, and cloud federation. The company is also announcing some new licensing models, such as usage-based licensing for cloud providers or bundles of licenses for enterprises.

One of F5's hopes for SDAS is that it can help speed up application for the company's customers. Agile development can lead an organization to create dozens of apps per year, but it doesn't create any faster way to get them deployed, says Lori MacVittie, F5's senior product manager for emerging technologies.