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Asterisk SCF: Scalability, Extensibility, Performance

asteriskscf.jpgThe big news coming out of Astricon last week in DC was the "Asterisk Scalable Communications Framework", a.k.a. "Asterisk SCF". The main goals of the project are to bring to the Asterisk platform:

  • Scalability (and high availability)
  • Extensibility
  • Performance

As a long-time fan of Asterisk (and user/administrator at various points of time), I can agree that all of these are areas where the base Asterisk IP-PBX can use some help.

Asterisk SCF is NOT a replacement for Asterisk. Instead it is essentially a framework for extending Asterisk and adding new functionality. As the executive summary outlines:

Asterisk SCF is designed as a distributed system of components that can be deployed in clusters on a single system or on many systems, transparently. Implementing Asterisk SCF as a cluster of small components allows it to naturally take advantage of the ever-wider multi-core CPUs being produced today as well as the movement to off-site or cloud-based computing. In addition, all operational data elements required by Asterisk SCF’s components are themselves managed by their own Asterisk SCF components, allowing for active/passive failover models with no disruption of service. The design also ensures active/active failover and load-sharing models can be supported. These design elements allow capacity to be added to an operating Asterisk SCF cluster by simply enabling additional component instances.

The "distributed system" part is the key. I wasn't at AstriCon, but from the Twitter stream as the event was unfolding it sounds like the Digium folks had a good bit of fun with the keynote announcement... including where they simulated three data centers and then pulled the power from one to show that calls stayed up. This kind of capability is what Asterisk needs to grow into new areas of deployment.

Asterisk SCF is still in development... only an "alpha" is available now and a beta will be out sometime in 2011. The Digium folks have put together a pretty comprehensive wiki about Asterisk SCF at:


I found the Introduction and FAQ both quite useful to read.

As a huge believer in the power of distributed systems, I wish the folks at Digium and within the Asterisk community all the best as they undertake this Asterisk SCF effort. I (and many others, I'm sure) will be watching and looking forward to seeing what evolves out of the effort. I'm sure there will be many more posts to be written...

P.S. FYI, Dave Michels published a good post over at the UC Strategies blog: "The Next Big Thing: Asterisk SCF

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