The consumer's dilemma
Despite what some of the marketing might lead one to believe, just buying another router with a bigger number on the box does not necessarily guarantee a good user experience. As Table 1 shows, many applications do not require all that much bandwidth per se. The real challenge is that each of several of these applications does rely on the network to behave as if it were the only application running.
In fact, this concept is not especially new. Quality of service (QoS) schemes, used to separate different application streams within a network, have existed in service provider and large corporate networks for many years. What the consumer may not realize, however, is that while a number of newer home networking devices may claim to implement these same QoS schemes, these technologies were designed for large networks actively managed by IT professionals.
In such larger environments, a manager manipulates QoS parameters to create a network that maintains necessary quality of experience (QoE) across a pre-defined set of applications. Such networks are typically designed such that all of the equipment meets certain minimum interoperable QoS requirements so that the most critical application(s) can be reliably deployed.
At the same time, other traffic on the network is closely controlled. Any large enterprise that deploys VoIP, for instance, will generally go through a deliberate process—first planning, then user trials—to ensure that the network is capable of carrying this new voice traffic reliably and without interference.
Compare this to the typical home setup, where the consumer simply piles in new equipment and software as the need arises. One day the only application is web browsing, and the next thing you know the network is delivering the latest online game and streaming soap opera episodes over a P2P file sharing service (such as the recently announced BBC iPlayer).
This all plays havoc with an unmanaged network. Bandwidth-hungry file sharing freely competes with delay-sensitive media traffic. Common user complaints include dropped (or poor quality) Voice Over IP calls, game lag, and pixilation or stuttering of video streams.
But no problem, just call the network manager, right? Wait, you are the network manager! Well, some growing number of consumers are really very tech savvy. Find the IP address and port numbers for your VoIP service, then prioritize that over everything else in the router if it supports rule based QoS. Wait, what about the XBOX? That needs to be high priority, too. Next, you download a game demo and it, too, messes with your VoIP call. Toss in that P2P application—they typically use all kinds of random ports—and what do you do with that?
If that's not enough, consider that usage patterns in a home vary dramatically through the course of the day. A home office by day—tons of e-mail and VoIP calls—becomes a conduit for IM video, online games, and YouTube in the evening when the kids get home from school.
What consumer wants to constantly tinker like this with the home network, day to day, hour to hour? In reality, rule-based QoS just wasn't designed for the emerging media-rich and preferably low-maintenance (or even install and forget!) home-networking environment.
A number of initiatives have sought to ensure that consumer networking equipment meets some minimum requirements for networking media in the home. Most notable are the certifications developed by the Wi-Fi Alliance, in particular the Wireless Multi Media (WMM) certification, and the work done by the Windows Rally team at Microsoft, which gave us the "Works with Vista" and "Certified for Vista" logos.
The good news is that if you see these logos on a networking box, you know that it has had to pass a specific, well-defined set of tests. In particular, devices carrying these logos will correctly interpret QoS tags attached to packets by an application and prioritize them appropriately.
For home networking gear, the Microsoft Vista logos also require added functionality that lets a Windows Vista-based PC interrogate the network to find out how much bandwidth is available between two points, then make that bandwidth available to Vista applications via Vista's "qWave" application interfaces.
The common drawback to relying on tags within the data, however, is that it remains quite difficult to make sure that all of your network components actually pay attention to the tags and avoid removing them. And along with some of these routers and other networking devices, many older PC networking cards and drivers are also tag-unaware, often stripping the QoS tags so that a packet appropriately tagged by a software application may still leave the PC minus the tag.
To be effective, tagging demands predicable end-to-end network behavior. If you have media on a Windows Vista PC that travels through a "Works with Vista" router to an XBOX or Windows Media Extender, your chances of everything working as you expect are greatly increased. If you connect an old Ethernet switch somewhere in the path then all bets are off. It was probably designed before all of the QoS requirements and standards were fully put in place.
Another drawback to tagging is that it is largely limited to traffic originating within your home network. Most of the content we're interested in, of course, resides out on the Internet. Unless these media are coming directly from a tagging-compliant, subscription-based service from your broadband provider, it will all arrive without a tag.
Service providers generally strip tags from traffic that originates outside their own networks because they need to manage the amount of bandwidth available for their own premium content. Stream a video from the Internet? Play an online game? Data from those applications will be untagged and thus ignored even by a fully implemented home network tag-based QoS scheme.