Small businesses adopting Voice over Internet Protocol and video teleconferencing are sometimes haunted by the convergence of voice and multimedia traffic onto data networks but yours doesn't have to be one of them. Affordable Quality of Service (QoS) mechanisms are available to oust the delays, jitters, bit rate errors and packet dropping over a converged network.
Quality of Service tools prioritize network traffic for better performance
Small businesses adopting Voice over Internet Protocol and video teleconferencing are sometimes haunted by the convergence of voice and multimedia traffic onto data networks – but yours doesn’t have to be one of them. Affordable Quality of Service (QoS) mechanisms are available to oust the delays, jitters, bit rate errors and packet dropping over a converged network.
QoS tools improve a network’s ability to deliver predictable service in support of specified applications and traffic types through network traffic prioritization. Traffic prioritization ensures that real-time applications, such as VoIP and video teleconferencing, get adequate service for optimal performance, without leaving other data-intensive applications 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.
Improve Network Performance:Although the capabilities and quality of IP solutions have advanced and their costs have decreased, the solutions are often plagued by noise and interruptions in service caused by delays, jitters and dropped packets. The root cause, though, is that the networks they are on are ill-equipped to handle the traffic.
There are three levels of QoS tools that can remedy these issues:
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 (FIFO) queuing in which packets are stored when the network is congested and forwarded in the order that they arrived to the network, once traffic eases.
Differentiated service identifies and classifies traffic in order to assign priority and meet latency requirements within available bandwidth, resulting in faster handling, more predictable service and fewer dropped packets. The network administrator pre-determines the priority of specific types of network protocol.
Guaranteed Service reserves network resources for specific types of traffic. The network administrator develops bandwidth classifications, and the bandwidth is divvied up amongst 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 upon the type of traffic being managed:
Classification tools, which identify, and in some cases mark, packets so they can be properly managed by other QoS tools.
Congestion avoidance tools, which prevent queues from filling and subsequently dropping packets.
Congestion management tools, which manage the queue and flow of network traffic when bursts – high levels of voice, video and data traffic – occur simultaneously.
Link efficiency tools, which 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, which limit the amount of bandwidth the packets can use in order to pace traffic at a controllable rate and prevent potential queue overflow.
All QoS implementations require a network monitoring system to track traffic, identify performance degradation and regulate service to provide 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.
What’s In QoS for Whom?
There are many benefits to implementing QoS on a network. End users experience greater clarity and availability in voice and video transmissions, mitigating static or noise interference. On the back end, QoS improves network administrators’ control over network resources and their ability to monitor network traffic and ensure that critical applications receive an appropriate level of service.
Successful QoS implementations can also deliver savings:
Users at different sites can make extension to extension calls over the existing data network rather than over traditional land lines
Businesses that implement a phone system with a 64-party audio conferencing bridge can save hundreds of dollars a month on conference call services
Session Initiation Protocol (SIP) trunks can cut phone bills by up to 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 associated costs
With QoS, teleworkers can use a virtual private network (VPN) IP phone from their home office, enabling forwarding of calls to their onsite office line and increasing their accessibility. “Soft phones” with QoS are also an excellent option for employees that travel frequently, because they allow remote users to call extensions at the main office for free via their laptops.
That’s not to say that QoS is without its challenges. QoS tools can relieve network congestion but sometimes there is just too much traffic for a network’s bandwidth to handle. To ensure quality, bandwidth must be high enough to support latency of 150 milliseconds or less. Switch failure is also a concern, because if one switch fails, they all fail – and businesses are left without access to the network. Recovery systems must be in place to get the network back up and running as quickly as possible.
Queue overflow 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. Network administrators should implement congestion avoidance tools, so that the queue does not fill up, and establish mechanisms that drop low-priority packets first.
A few suggestions to get the most out of your network with QoS:
Before implementing QoS, consider private branch exchange (PBX) or hybrid phone options that allow least cost routing – when a call is automatically routed through the most inexpensive path possible
Determine if QoS is the right choice for the business and network needs. Consider the applications that run on the network and the cost of implementing QoS, and do not migrate unless it will save the business money
Assess network traffic to determine which applications are most critical to the business and which require the most bandwidth and availability
Select a vendor who provides training and guidance for the implementation process, as well as a reputable managed services provider if the business does not have an in-house IT professional
Establish minimum requirements for availability and bandwidth, traffic management performance, and the end user experience
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. It is an ongoing process because application and network demands are constantly changing, so network administrators should actively manage the complete system. Administrators seeking to optimize network infrastructure and improve the performance of bandwidth- and data-intensive applications should give QoS serious consideration.