BIOS: Technology Means Business

Voice over IP (VoIP) is a dream concept that has been around for some time but that is only now starting to be taken up as a serious business tool. Quality and reliability issues have been responsible for slowing the adoption of VoIP within the enterprise arena but there are many solutions available today that are combating these issues and preparing the market for the revolution that is VoIP.

In fact, according to recent enterprise surveys, VoIP deployments will grow faster in the next 18 months than any other category of enterprise applications. So prevalent has it become that most major enterprises have VoIP projects either underway or in the testing and evaluation stage.

As VoIP becomes more prevalent throughout the enterprise, IT staff are being forced to address the unique requirements of delivering voice to branch office and remote users. At the same time, to keep user performance acceptable for the newly centralised applications, they must also accelerate other business critical applications over the WAN. As data applications have very different delivery requirements from voice, video, and real-time applications, this can be a challenging task to accomplish. VoIP is a real-time application that uses the User Datagram Protocol (UDP) for transport (as opposed to the Transport Control Protocol, or TCP, which is used by many other enterprise applications).

As a result, companies considering VoIP and consolidation projects will require an acceleration platform that is specifically architected to support UDP, including advanced QoS capabilities to minimise jitter, latency and packet loss. It is not enough to simply reduce the bandwidth usage of other applications in order to make room for VoIP traffic over the WAN. Rather, it is a requirement to maintain LAN-like network characteristics over what will be an over-subscribed or congested WAN, without inducing added latency. In addition, VoIP is highly sensitive to WAN traffic quality - jitter, latency and packet loss.

The ITU (International Telecommunication Union), for example, recommends that the end-to-end delay associated with a voice call not exceed 150ms. Experience has shown that it is possible to exceed that goal by a small amount, but voice quality will degrade if latency becomes too large. Jitter is a measure of how packet delay changes over time. While the vast majority of data applications are not impacted by jitter, voice is different. According to well accepted standards, if jitter exceeds 30ms, voice quality will degrade noticeably.

In the VoIP world, voice quality is measured by a ‘Mean Opinion Score’, which is a number between 1 and 5 used to quantitatively express the subjective quality of speech in communications systems, especially digital networks that carry VoIP traffic. Anything above a 4.0 is considered toll grade. On a standard WAN link with congestion, however, MOS drops to 3.0. This is well below toll quality. A variety of tools can be used to overcome the challenges of delivering VoIP across a WAN, ensuring that MOS remains above toll grade.

There are several measures that companies can take to ensure that their voice traffic is not degraded by other services running over the network. After all, voice will not tolerate losses in the same way that data can. In voice communications, packet loss shows up in the form of gaps or periods of silence in the conversation, leading to a clipped-speech effect that is unsatisfactory for most users and unacceptable in business communications. Quality of Service (QoS) enables enterprises to deploy VoIP in conjunction with other enterprise applications. In addition to honoring existing QoS markings, acceleration solutions provide native support for advanced QoS, including sophisticated classification logic, a variety of packet marking techniques, queuing, and traffic shaping. Also, they can ensure that specific applications, like VoIP, are guaranteed appropriate WAN bandwidth.

Employing advanced header and payload compression is a tried and tested technique for reducing the amount of voice traffic traversing the WAN. This saves on WAN bandwidth utilization which means that application response times are reduced, thus giving greater performance to the users. Of course, enterprises have to cater for normal traffic flow most of the time but issues tend to be raised at times of peak usage. Adaptive Forward Error Correction (FEC) can help to improve VoIP performance during periods of high packet loss. By dynamically adding FEC packets, a WAN acceleration appliance can recreate lost packets with extremely low latency. The result is consistent quality of voice even during periods of network congestion.

Another tool in the arsenal is that of packet coalescing whereby a number of smaller packets are repackaged into a single larger packet. By doing this in connection with header compression, acceleration tools can reduce the amount of bandwidth required for voice thus impacting on the quality of the service and the performance of the network.

Finally, the network administrator can use real-time data reduction techniques to reduce the amount of repetitive information that crosses the WAN by delivering duplicate information from local data stores whenever possible. This can be broadcast voice traffic, such as audio streaming or voice mail, as well as redundant bits of information that accompany normal voice calls (e.g., silence suppression). Data reduction can also be used to reduce the amount of non-voice traffic on the WAN, freeing up the total amount of available resources.

Virtually every study of the topic indicates that the percentage of companies that have deployed VoIP has steadily increased to the point where the majority of companies have already begun to deploy it. Market research also indicates that over time, most companies expect to increase their deployment of VoIP. The increasing percentage of companies that are deploying VoIP introduces unique application delivery challenges for distributed enterprises. Application acceleration solutions can help significantly. By combining innovative data reduction techniques with advanced Quality of Service, compression, and loss mitigation, they can ensure LAN-like toll quality across most WAN links.

There is little doubt that VoIP technology will revolutionise the telecommunications industry and, if used properly, can create many positives for companies and private individuals alike. Where the enterprise market is concerned the time must be right for implementation and the early issues with the technology must be addressed fully. However, there are technologies advancing at a mighty pace to make VoIP a reality for everyone, from the single consumer to the large, multi-national organisation. Indeed, from real-time conversations to audio streaming, WAN acceleration is the answer when enterprise VoIP is calling.