Small businesses converging voice, video, and data traffic sometimes end up with haunted networks, but you can exorcise the demons. Affordable QoS (Quality of Service) mechanisms are available to oust the goblins that cause delay, jitter, bit-rate errors, and dropped packets.

QoS tools use prioritization to improve a network’s ability to deliver service in support of specific applications and types of traffic. Traffic prioritization ensures that real-time applications, such as VoIP and video teleconferencing, get adequate service and other data-intensive applications aren’t left in limbo.

An investment in QoS can improve the speed and quality of such applications, and reduce infrastructure and transmission costs — an added benefit for businesses with their eyes on the bottom line.

Make Your Network Performance Howl

Although the capabilities and quality of IP solutions have advanced and their costs have decreased, the solutions are often plagued by noise and service interruptions caused by delays, jitter and dropped packets. The root cause, though, is that the core networks are ill-equipped to handle the traffic.

There are three levels of QoS tools that can remedy these problems:

Best-effort service provides basic connectivity without prioritization of specific flows or applications, so there is no guarantee of service. A good example of this is first-in, first-out queuing, in which packets are stored when the network is congested and forwarded in the order they arrived once traffic eases.

Differentiated service identifies and classifies traffic to assign priority and meet latency requirements within available bandwidth. This results in faster handling, more predictable service and fewer dropped packets. The network administrator predetermines the priority of specific types of network protocols.

Guaranteed service reserves network resources for specific types of traffic. The network administrator develops bandwidth classifications, and the bandwidth is divided among them to guarantee availability to the highest-priority traffic while serving lower-priority traffic on a best-effort basis. This prevents low-priority flows from superseding high-priority flows.

Different QoS tools are available to enable better network service to applications, and should be selected based on the type of traffic being managed. All QoS implementations require a network-monitoring system to track traffic, identify performance degradation, and regulate service to give precedence to voice and video traffic. Networks require switches that support QoS and 802.1p standards — a standard that accelerates the classification and filtering of traffic.

Concerns of A Converged Network

Trick Or Treat: What’s in QoS For Whom?

There are multiple benefits to implementing QoS. The quality of voice and video transmissions improves and, at the back-end, QoS allows administrators to control network resources and monitor traffic to ensure critical applications receive appropriate service. All of that, of course, makes it less daunting to adopt convergence technologies which can deliver ghoulish savings.

Users at different sites can make extension-to-extension calls over the existing data network, rather than requiring additional land lines. Businesses can implement 64-party audio-conferencing bridges that save hundreds of dollars a month on conference-call services.

Session Initiation Protocol trunks can cut phone bills, by as much as half, by connecting the phone system to traditional telephone lines via the Internet over a data T1 line, reducing the use of voice T1 lines and other associated costs.

What’s more, with QoS, teleworkers can use an IP phone from their home office over a VPN link, making it possible for them to handle calls as if they were in the corporate office, increasing their accessibility. ‘Softphones’ — software on laptops — with QoS also are an excellent option for employees who travel frequently, because they allow remote users to call extensions at the main office for free via their computer.

That’s not to say that QoS is without challenges. QoS tools can relieve network congestion, but sometimes there is just too much traffic for the given bandwidth. To ensure quality, bandwidth must be high enough to support latency of 150 milliseconds or less.

Switch failure is also a concern for businesses that use IP phones with dual-port switches to connect the phone and a computer through a single drop, applying QoS to route voice traffic ahead of data traffic. If the two-port switch fails, the phone and the computer both lose connectivity. Likewise, users will lose connectivity if the LAN switch fails. Recovery systems must be in place to get the network back up and running as quickly as possible. Many businesses operate a POTS (plain old telephone service) line to maintain some access during these times, and some businesses avoid the potential challenge altogether by implementing a LAN for each type of device, though this option is more costly.

Queue overflow — when the number of incoming packets exceeds the rate at which the network can process them — can also be a challenge because a full queue cannot receive any additional packets and will drop those that arrive last, regardless of their priority level. This condition usually happens when voice packets are not prioritized ahead of data packets or QoS is not implemented correctly, causing jitter and echo. Network administrators should implement congestion avoidance tools, such as virtual LANs, so voice packets receive greater priority and the queue does not fill up. They also should establish mechanisms that drop low-priority packets first.

Make Maximum USe

Finally, here are a few suggestions about getting the most out of your network with QoS:

Determine if QoS is right for you by weighing the benefits to the network applications against the cost of implementing QoS.

Assess network traffic to determine which applications are most critical and which require the most bandwidth and availability. Failure to conduct a network assessment is the most common mistake and can lead to significant expenditures.

Select a vendor that provides training and guidance for the implementation process, as well as a reputable MSP, if the business does not have an in-house IT professional.

Establish minimum requirements for: bandwidth among multiple office sites; availability of service for priority applications; traffic-management performance — typically a latency of 150 milliseconds or less; and the user experience and satisfaction with the performance of the phone system — there should be crystal-clear sound without jitters, drops, or echo.

Assess the results to verify that the service is performing at the desired level.

QoS is at the leading edge of network management, and is necessary for the optimum performance of networked applications. However, managing QoS is an ongoing process because application and network demands change constantly. If you install QoS tools to optimize network infrastructure and improve the performance of bandwidth- and data-intensive applications, you’ll have to actively manage the complete system; but the network, and those it supports, will be the better for it.

— Network World

The Channel View

Types of QoS Tools

Classification tools: These identify and mark packets so they can be properly managed by other QoS tools.
Congestion avoidance tools: These prevent queues from filling and subsequently dropping packets.
Congestion management tools: These manage the queue and flow of network traffic when bursts occur simultaneously.
Link-efficiency tools: These fragment large data packets and interleave real-time packets between the fragmented packets so they can be sent without delay or interference.
Shaping/policing tools: These limit the amount of bandwidth the packets can use, to pace traffic at a controllable rate and prevent potential queue overflow.

To Walk The Bridge Or Not

The market is abuzz with analyses of the success of converged networks, with one segment claiming heaven behind troubled doors (read bottlenecks), in terms of reduced cost of communication and ease of operation. Non-believers denounce it on grounds of poor broadband reach, making a seamless converged network seem impossible. However, once connectivity is dealt with, all agree that there is immense potential in the converged network market. A Frost & Sullivan analysis suggests that the current $550 million market is poised to double by 2015.

Girish Trivedi, Deputy Director, ICT Frost & Sullivan, says, “We track this market from a perspective of unified communication and look at the share of IP endpoints sold. These have shown significant growth, in the range of 15 to 20 percent Y-o-Y, which is very healthy.”

Today, many players offer solutions to establish a sustainable converged network, but the bandwagon is being led by Cisco, Avaya, and Nortel. “We have seen a good uptake of this solution in recent years, especially by companies that are moving to a new location and hence opt for a converged network, as opposed to the traditional one,” says Trivedi.

Naveen Mishra, Lead Analyst, Mobile Handsets and Telecommunication Services Research, IDC India agrees, “The industry is increasingly adopting and moving towards MPLS, VPN and packaged switching, as opposed to the traditional ATM and frame relay, which are slowly stagnating. They are discounting their legacy systems or using them as secondary or supplementary modes of connectivity.”

The momentum for converged networks in India is mostly noted in two verticals, namely the banking and ITES sector.

Analysts agree that there is potential for growth but there are certain issues that are holding back companies. Trivedi explains, “While there are many advantages of a converged network, there are bottlenecks too. Short-term hybrid migration to converged networks is still in question, because of its RoI. Only when one has a large-scale movement from traditional to IP, over a period of 5 to 7 years, that the TCO and RoI move to positive indices.”

—Tasneem Balapurwala