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Switch leaders offer true fault tolerance

Posted: 18 Sep 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Quintum Technologies? switches? VoIP? session initiation protocol? SIP?

Now that VoIP systems are permeating corporate offices and being deployed next to analog legacy systems, the need for fault-tolerant controllers is growing. Several leaders in soft switches and IP multimedia subsystems are expanding systems to add high availability and true fault tolerance to session initiation protocol (SIP)-based packet networks.

Quintum Technologies Inc. is adding a software SIP proxy to its MultiPath switch architecture, even as it extends switch families down into branch-office systems. The existing Tenor AX series for large enterprises, as well as the new Tenor AF for small-office and branch-office applications, will be offered in a new "S" series for survivable architectures.

Meanwhile, Radisys Corp. and GoAhead Software Inc. have announced a Promentum family of systems based on), integrating Radisys boards and systems with GoAhead's SelfReliant software for high availability. GoAhead president Jim Ewel said VoIP gateways and WiMAX controllers were some of the first ATCA-based systems requiring failover features to prevent outages.

Advantages of SIP proxy
At Quintum, the company elected to implement an embedded SIP proxy as the most cost-effective way to offer high availability in existing Tenor switching systems. VP of marketing Chuck Rutledge said Quintum had always maintained that the flexibility of SIP client protocols justified a software-failover architecture, but customers helped push for the solution as they realized the advantages of keeping branch-office voice connectivity up during outages.

"There's at least two distinct goals hereallowing users to access analog systems like fax machines, and making them feel more comfortable with IP PBXes," Rutledge said. "What people don't realize right away is that a survivable VoIP solution makes it easier to transition legacy PBXes to IP PBXes. It also makes call routing more flexible across circuit-switched and SIP systems."

The ability to make both H.323 and SIP endpoints survivable, and to provide E911 services in IP networks, makes IP gateways more attractive to carriers. Quintum began with Tenor products aimed primarily at the enterprise.

For GoAhead and Radisys, the offering of ATCA systems preintegrated with fault-tolerant software is a feature demanded not only by Tier 1 telecom equipment manufacturers, but also by the subsystem vendors serving the Tier 1 suppliers. Eric Gregory, senior manager of ATCA software at Radisys, said open ATCA platforms may have been greeted with some trepidation at first, but leading OEMs and ODMs have caught on to ATCA during the past months.

The Promentum chassis-based systems offered by Radisys use GoAhead software integrated with Wind River Systems Inc.'s carrier-grade Linux, though customers can also configure it with alternative kernels from companies such as Monta Vista Software Inc. and Red Hat Inc. Ewel said that the abstraction provided by the Hardware Platform Interface (HPI) defined by the Service Availability Forum is as important to some customers as the failover features of the software itself.

The systems from Radisys and GoAhead, for which Radisys will serve as support contact, will allow external management through Simple Network Management Protocol Management Information Bases (MIBs), as well as MIBs accessed through the HPI resources.

The real advantage in using open hardware architectures and software modules, Ewel said, is that network managers can set custom policies for "hot-swap" board failovers, and for the management of alarms when components, boards or network ports go out.

- Loring Wirbel
EE Times

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