While we have heard about Voice over Internet Protocol (VoIP) technology for some time now, other 'connection-oriented' applications -- such as audio and video -- are on the packet horizon. The questi...
July 1, 2002
While we have heard about Voice over Internet Protocol (VoIP) technology for some time now, other ‘connection-oriented’ applications — such as audio and video — are on the packet horizon. The questions to be answered are: how soon, and at what cost?
‘Data’ network operators are giving ‘voice’ traffic a lot of attention these days. ‘VoIP’ it’s often called — Voice over Internet Protocol. So, what does that mean?
First, take note that everything on a network is data — ‘voice’ included. What’s at issue is whether ‘data’ networks can service certain ‘connection-oriented’ applications such as audio and video.
But let’s start at the top.
In general, there are two basic ‘types’ of data and two basic telecommunications models — ‘connection-oriented’ data and ‘connectionless’ data.
Connection-oriented data — audio, video and some timing and control data — are best streamed over dedicated communications channels called ‘circuits.’ These circuits — interconnected wire pairs in the most basic sense — are ‘set up’ (connected) and ‘torn down’ (disconnected) by electronic ‘switching’ equipment as required. Once a circuit is in place, no other traffic is allowed to interfere.
Signalling can be slow (just listen to your modem connecting) and noise and interference can cause limited data loss, but connections are reliable and available everywhere. Circuit use is typically charged based upon both time and distance. Traditional telephone is based upon circuit-switched networks.
On the other hand, connectionless data — file transfers, e-mail messages, on-line transactions and Web pages — have different network needs. Rigid circuits are not required because the data is not being used in real-time. And while no one minds waiting a few seconds for the data to arrive, transmission errors must all be corrected.
In this transmission model, very fast, specialized, computers break the data files into thousands of small ‘packets’ — usually only a few dozen bits of information each, address them for reassembly at destination, and send them out over a shared infrastructure. Transit may take a few seconds, but error correction is part of the process and new efficiencies are possible through bandwidth- and infrastructure-sharing and greatly increased routing flexibility.
And packet connections are ‘always on.’ There is no dialling — unless you are using a circuit switched telephone network to gain access. Packets are simply addressed and pushed into the data stream in much the same way we merge onto a busy sidewalk. Once in the flow, intelligent network devices (routers and switches) redirect individual packets until they reach a desired destination. Charges are typically volume-based and there are no long-distance tolls.
So while circuit networks provide real-time connectivity, packet networks can connect everything else.
Over the past several years computerization has pushed business information systems onto the Internet, often leaving circuit-based applications such as telephone and video as odd man out, isolated from the other mainstream business systems.
BEST OF BOTH WORLDS
Now users want the best of both worlds — reliable real-time connectivity over easy, cheap and reliable packet networks. They want this, not as much to save money (though that is usually one benefit of implementing a VoIP solution), as to unify communications channels, ease information flow, integrate business applications, extend mobility, and streamline management and administration.
But carrying voice traffic over packet networks without clicks and pops is a start. How do you ring the phone at the other end of the Internet or forward calls to your Palm Pilot? How about message waiting lights, phone numbers, touch-tone dialling, voicemail and other signalling and service features unique to telephone service? Who generates the busy signals? Will faxes work? What about call waiting and conferencing calls?
Thus network vendors are developing and implementing various ‘Quality of Service’ (QoS) technologies that prioritize and expedite data movement across packet networks based upon service needs, while offering bullet-proof, ‘telco-grade’ computer systems to boost infrastructure reliability.
“There’s a big difference between providing Internet access and providing voice services,” says Mark Quigley, Research Director at the Yankee Group in Canada. “Everyone knows what it’s like to be without e-mail for a couple of hours, but if you’re a business and lose your local and long distance voice service, it’s an entirely different experience altogether.” But price isn’t everything, says Quigley. “Quality of service and knowing your service is going to be there tomorrow is probably more important,” he adds. “Simply because voice services are critical.”
FINDING COMMON TECHNIQUES
The technology has come a long way on this front as well. Most equipment vendors have developed methods for doing all of these important functions across their own boxes. Now the problems lie in finding common techniques so QoS and feature sets can be maintained over disparate networks. That initiative is well underway today, but it may be some time before these resources become commonplace in pubic packet networks.
“You’ll be seeing people use VoIP internally far sooner than they’ll start using it externally, but we’re looking at it from both angles,” says Eric Greenwood, COO and CIO of Markham, Ontario-based Minacs Worldwide, one of North America’s largest call centre operators. The company is currently deploying VoIP into a new site in Guelph, Ontario.
“The opportunity for us is the ability to build new sites very quickly and cost-effectively without having to put the traditional infrastructure in place,” says Greenwood. “We’ll be pushing both voice and data to the Guelph site from our Avaya telephone switch in Toronto,” he says. All will travel over the company’s private network. “And because VoIP works very well in a closed environment, there are no QoS or bandwidth issues,” he adds.
Cabling isn’t usually a migration problem either. Optical fiber, microwave, RF and copper cabling systems are very similar for both voice and data networks, so in newer networks it is often simply a matter of changing out network boxes. For instance, Category 5 cable may well carry both the local area network (LAN) and the telephone system already.
Today though, because the two applications have such different requirements, each network usually requires a separate infrastructure. With VoIP, all of that changes. And that second drop simply becomes a safety net.
But Greenwood sees two major impediments to telephony over the Internet: The universal adoption of open Internet telephony and QoS standards, and bandwidth availability. Luckily there has been a lot happening on both fronts.
On the packet standards front, many international standards bodies such as the IEEE, ANSI and the TIA are carrying out much of this cross-standardization of packet technologies. The ‘802 working committee’ is one example. An IEEE-, TIA-sanctioned arm of the International Telecommunications Union (ITU), the 802 committee has, for several years now, been working behind the scenes to bring as much commonality as possible to packet networks of all types. Based (roughly) upon good old Ethernet, 802 standards have become a common denominator.
Wireless LAN variants are the most visible members of this extensive effort, notably 802.11b or ‘WiFi’. But 802 is also the main-squeeze of most office networks as well — 802.1 is standard Ethernet. Gigabit Ethernet, ATM, SONET and most 3G wireless networks are compliant as well — on copper, optical and wireless links. Even X.25, the oldest of the common packet protocols, has an 802 equivalent. So the pipes in many modern networks are ready for almost anything.
THE STATE OF VOIP TODAY
Thus far, industry watchers say it seems pretty clear that circuit switching will remain an option for some time, particularly in public networks. But in controlled private packet networks across campuses, throughout commercia
l buildings, and in specialized installations such as call centres, telephony-over-packet is moving ahead at a steady pace. Recent industry reports suggest that most enterprises today are either implementing or are experimenting with voice and video over packet.
Avaya, 3Com, Mitel and several dozen other well-known and not-so-well-known network vendors already offer an extensive line of competitively priced, full-function voice over packet telephone systems for both small and large organizations. At the same time, Microsoft, Oracle, Siebel and other major software vendors are adding VoIP functionality to popular business applications, so the telephone and data systems function hand-in-hand.
Telephony over the Internet though, remains all too reminiscent of CB radio, with its clicks, pops, delays and dropped frames. But this should change as packet networks mature. Next generation gear is now coming to market based upon enhanced IP technologies such as Multi-Level Protocol Switching (MLPS) and IPv6 — newer packet schemes that bring increased security, improved reliability, advanced QoS and expanded addressability to IP networks.
On the hardware front, HP, Sun Microsystems, IBM, and others now offer fault-tolerant ‘telco-grade’ computer systems to bring greater reliability to data systems.
“Convergence is coming,” says Samantha Kane, telecommunications consultant and Founding Partner of Kane McKay Associates of Belleville, Ontario. “It won’t be today,” she adds. “And it won’t likely be tomorrow. But sooner or later, the networks will come together. Though I doubt we’ll be using any less cable.”
Chris Blythe is a broadly published writer and infocom analyst. Send correspondence to firstname.lastname@example.org.