Convergence: Tools for Traffic

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From the earliest days of networking, the term “convergence” has been interpreted to mean the confluence of different types of traffic across the same networking media. At the outset of this phenomenon, one dealt with tools and technologies designed to let voice and data networks share the same media, especially when expensive, high-bandwidth carrier connections were common. Because it permits infrastructures—and thus, related costs, equipment and links—to be shared, convergence has always come in for a fair amount of buzz and attention. But in an age of the ubiquitous Internet and ever-higher bandwidth links to homes as well as offices, convergence has been expanded to include whatever kinds of traffic one can wish for or imagine.

These days, the biggest buzz in convergence circles isn’t about linking private telephone systems with data networks, or vice versa. It’s all about various ways to use the network directly for various types of traffic, including voice, video and other forms of what are sometimes called “media-rich communications” (which combine data, sound and images into complex communication streams).

As convergence needs have evolved, so have the tools and technologies to support them. Today, the biggest topics in convergence have to do with the following types of communication activities:



  • Voice over Internet Protocol (VoIP): This rapidly exploding voice communications technology permits voice traffic to traverse public and private IP networks. Combined with phone switches and other equipment, VoIP phone users not only can call each other, but also can dial into the old-fashioned public switched telephone network (PSTN). Given that delays in voice communications can be problematic, this type of service is normally classified as real-time.
  • Voice and Video Communications: This interesting family of applications and services is built largely around the H.323 standard developed by the International Telecommunications Union (ITU) to define how audio visual conferencing data should be transmitted across networks. As implemented for TCP/IP, this pretty much sets the stage for how webinars, online training, networked meetings and other forms of real-time communication are orchestrated and handled.
  • Wireless Link-Ups: This is more a matter of extending the types of communication onto wireless network segments, but also embraces emerging generations of wireless phones and mobile devices with support for VoIP, streaming media and possibly even voice and video communications.


Another interesting form of convergence occurs in the proliferation of multi-purpose access devices. At one time, purchasing an Internet access device meant buying a single-purpose device designed to deliver Internet connections to individual computers or entire networks. Especially for broadband Internet services, a whole new class of devices has emerged in the past two to three years that typically integrates Internet access, security capabilities, network services and connections, and more in a single inexpensive box. Manufacturers like Belkin, D-Link and SMC (among others) all offer devices for less than $100 that include some or all of the following capabilities:



  • Cable modem Internet connection: Some support both DSL and cable connections.
  • Four or more ports of switched 10/100 Ethernet: These devices also come in wireless implementations with support for 802.11b typical, and 802.11g increasingly evident. For wireless networks, devices can usually handle eight or more simultaneous connections. One or more USB connections for direct PC link-ups also is pretty typical.
  • IP services: Most of these boxes include built-in routing, DHCP and network address translation (NAT). Some even include higher-level content filtering or print server functionality as well.
  • Internet security capabilities: Most of these devices offer built-in firewalls with both inbound and outbound traffic screening capabilities. Many also offer stateful inspection and limited intrusion detection and prevention capabilities.


That’s a lot of functionality for little money, but where convergence really comes into play is with an increasing number of offerings that include telephone jacks and support for one or more VoIP-capable or conventional telephone handsets. Other evidence of this kind of convergence includes another class of similar products built around telephone handsets. These integrate the same kind of functionality just described—Internet link-ups for DSL and/or cable, wired or wireless local network links, IP services and security capabilities, along with VoIP support—inside a telephone-shaped device. A broad range of vendors, from giants like Cisco Systems to upstarts like Zultys, are charging into this space with compact, affordable device offerings. Though these do cost more than multi-purpose Internet access devices, they integrate powerful telephone service capabilities along with wired or wireless handsets and headsets, along with everything else.

Making Networks Ready for Real-Time
Of course, the introduction of real-time protocols and services such as voice or conferencing onto conventional data networks can be an interesting process. In fact, most experts recommend that some forms of planning, modeling and analysis be performed before setting such things loose on any network. This goes double when it comes to implementing plans to add voice or conferencing services.

Ultimately, it’s all about tolerable delay and quality of service issues. Both phrases touch on needs for the packets of data to not take too long in transit, to experience no unusual degrees of loss or rejection along the way, and to arrive in some reasonable semblance of the sequence in which they left—at least, within the levels of tolerance for delay that these forms of communication can reasonably support.

To facilitate introduction of voice and conferencing services onto networks, technology vendors have developed all kinds of tools. These are usually divided into two major classes:



  • Planning and modeling tools: These tools depend primarily on simulation of events and traffic on modeled versions of real (or planned) networks to help network professionals decide if they can handle planned levels of real-time traffic and activity, along with whatever other more conventional uses they may support.
  • Analysis and characterization tools: These tools can measure delays, monitor quality-of-service behavior and, in general, probe and measure network performance and other characteristics to see how well or poorly they can handle real-time traffic, and what kinds of loads are workable, as well as where things start to break down or become unworkable. These tools not only measure actual traffic and network characteristics, but also can simulate traffic loads to see how networks behave when real-time traffic is introduced onto them.


It’s eminently possible to step into a situation where management’s and users’ high expectations about the usability and productivity gains they will get from convergent technologies and communication are dashed by network problems. Thus, it’s essential to make sure not only that initial usage scenarios are workable, but also that enough room for growth and increased capacity potential is built into initial designs so that constant upgrades don’t become the norm. Once users become accustomed to services, no matter how advanced, they soon come to depend on them, so the last thing you want to do is put them in a situation where those services degrade or become temporarily unavailable on a noticeably regular basis.

What Convergence Really Means
Introduction of voice and conferencing services often necessitates upgrades of network infrastructure to accommodate performan

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