Redfone Brings High Availability to Asterisk

By: Richard “Zippy” Grigonis

Redfone Communications, LLC (www.red-fone.com) was founded by people who had successfully used open source Asterisk (News - Alert)-based Voice-over-IP (VoIP) technologies in their previous businesses. Immediately grasping the cost advantages and rich functionality of the immensely popular Asterisk software IP PBX (News - Alert), they realized that a business opportunity existed, and so Redfone was founded in 2003 to design, develop and deliver next-generation Asterisk-based communications solutions to small and mid-size businesses.

As Avionics engineers with considerable avionics data communications expertise, however, they realized that for mass implementation of Asteriskbased systems to succeed, major changes had to occur relating to hardware compatibility, scalability, and redundancy. Thus, Redfone Communications was reorganized in 2005 with the new mission of providing solutions to assist Asterisk developers and installers by extending the Linux concept of hardware independence. Redfone’s first product, the foneBRIDGE, received immediate acclaim by both installers and industry analysts. Its latest incarnation, the foneBRIDGE2, is already used at hundreds of locations worldwide as part of various complex implementations including contact centers, financial institutions, emergency services, and inside telcos. There are even hundreds of enterprise-sized deployments.

Redfone’s President, Mark Warren, says, “Until recently, it was difficult to find a truly fault tolerant, highly available open source telephony platform, especially from a PRI/TDM standpoint. Cumbersome, underpowered and expensive fault tolerant systems had long existed in the world of high-end, expensive PBX and computer telephony platforms, but in the open source world, a simple, cost-effective communications hardware device was pretty much non-existent. We at Redfone have met this need with our foneBRIDGE2, which enables IT managers and systems integrators to implement Asterisk® and even other open source software-based telephony platforms in demanding environments where downtime directly affects revenue.”

In Search of High Availability (HA)

In a conventional Asterisk implementation, T1/E1 connectivity is provided by PCI based interface cards on a single server, thus making the server a single point of failure and reducing its overall integrity and availability. For many businesses, voice is a mission critical application and so placing it at risk is simply unacceptable.

“A number of open and commercial tool sets are available for building high availability, fault tolerant Linux clusters,” says Redfone’s Mark Warren. “The general objective of deploying HA in a server environment is to provide reliability, availability, and serviceability [RAS]. As an externalized point of T1/E1 termination, the fone- BRIDGE2 is decoupled from the single server limitation. When combined with the proper tool set, the resulting implementation can provide rapid and automatic failover amongst a cluster of servers.”

Warren elaborates: “The most common toolset used to support HA when paired with the foneBRIDGE2 and Asterisk is the ‘heartbeat’ tool from the Linux-HA project [www.linux-ha.org]. As its name implies, the ‘heartbeat’ monitors the state of two or more nodes [servers] in an Asterisk cluster. If it detects a fault – when a primary node stops responding to the heartbeat messages, for example – it executes scripts enabling it to quickly failover to a secondary server. This process is transparent and occurs without user intervention.”

As opposed to human technician-guided troubleshooting and repair that can take minutes or even hours, foneBRIDGE2’s rapid failover and system recovery takes place in seconds. The foneBRIDGE2 re-configuration options work rapidly, and the device can be re-programmed on-thefly via high availability tools so that a TDM stream is immediately routed and calls to a secondary standby server occur in under one second.

“Add to that the minimal time the server takes to start Asterisk and clear circuit alarms, and a customer’s stand-by server can be operational and handling voice calls in under three seconds,” beams Warren.

Maintenance and Upgrades – Uptime and Scalability

Back in the day, your IT staff often had to bring down a server just to load a minor software patch or upgrade. With foneBRIDGE2, however, your server admin can manually failover to a back-up server and keep the voice system operating while performing upgrades or patching on the primary server.

“On a related note,” says Warren, “once connectivity is externalized in this way and not tied to any single server or PCI card – Ethernet is the only hardware requirement – then adding additional T1/E1 capacity to an Asterisk implementation is now simplified and requires little or no operations downtime. Thus, scalability is no longer a challenge.”

Redfone’s foneBRIDGE2 is truly a flexible, ingenious device. It’s an external device that installs on your network quickly, with no need to open up your server and install it inside your chassis. Moreover, it has a slew of absolutely unique features, such as rapid failover capability on an Asterisk/ Trixbox cluster. It even supports “mixed-mode” operation support, so that T1, E1 and RBS/CAS services are configurable on a per-port basis. Best of all, foneBRIDGE2’s price points are comparable to equivalent dual and quad-port PCI products. And if by chance you get confused, Redfone supports both Asterisk and trixbox users – everything from simple questions and configuration help to engineering consultation on the proper dimensioning and implementation of your systems.

Anyone serious about open source telephony should take a look at Redfone’s products. IT

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