“However, it is effective only insofar as the network is reliable. Network or server failure means employees can quite simply not make phone calls, and the knock-on effect of this to most businesses would be very significant. This is why survivability is important. However, it is key to take a comprehensive approach and allow communications systems not just to survive, but to retain all their features even during a network failure. This has led to the new term “Fully featured availability”, describing solutions that provide modular software architecture, server reliability, fail-over capabilities and back-up mechanisms.
Network and system outages come in many forms. While the total loss of a building through an accident or natural disaster is very rare, failures of equipment, power or network services are more common. Therefore organisations must evaluate the impact of such potential events. Critical sites which host major components of the system should consider enhanced protection by investing in uninterruptible power supplies and back-up power generators, as well as having more than one IP service connection with diverse routing.
As well as addressing hardware continuity, organisations should prioritise the types of communication carried. They tend to have a mix of call traffic, with some traffic through the public-switched telephone network, and some purely internal. The relative size and importance of these flows will determine where organisations should spend money.
Miercom, an independent testing lab, recently tested high-end IP-PBXs, including Siemens, 3Com, ShoreTel, Alcatel and Avaya. The IP-PBX test bed comprised two simulated sites, a “headquarters” and a “remote office”, connected by an IP- WAN link. 3Com’s VCX was deemed to deliver the “Best Distributed Survivability”.
It was found that 3Com’s key software functions – including call control and voicemail/messaging – can run together on the same, or on different, distributed servers. It also ships on one or more highly reliable and redundant, Intel based IBM servers running Linux, and is now also offered by IBM on its System i platform.
Any controller can manage its own IP telephony network and concurrently serve as back-up to one or more remote, distributed call controllers. Back-up configuration files are extremely efficient, entailing less than 10 Mbytes, can be replicated on controllers anywhere and are all automatically updated whenever there’s a configuration change.”