Craig Rosewarne, sales manager at Westcon, maintains that quality of service (QoS) on Vanguard Managed Solutions (formerly Motorola Networking) allows network operation trade-offs to be minimised with respect to throughput, delay, bandwidth, network availability, jitter, packet loss and acceptable error rates to provide optimisation of response time, performance, and voice and video quality.
QoS is the performance of user/application traffic flow through networks intended to support many different types of traffic services. The "best-effort" service that was adequate a few years ago no longer meets enterprise expectations.
Challenges faced by the network administrator include applications that flood the network on a daily basis, tight budgets, mission-critical applications requiring priority service and extremely delay sensitive voice and video.
The ultimate challenge in supporting multiple traffic types is to assure acceptable levels of service to network users while minimising costs of network equipment and administration. The mechanisms provided by QoS deal with the normal fluctuations of busy networks that handle the different service requirements of data, voice, fax, and video traffic.
Examples of applications which can utilise QoS:
Finance
Problem: A central bank site receives the records of all daily transactions from branches, remote sites, and ATM machines which results in a massive FTP transfer every day between 3pm and 5pm. This results in very slow computer transactions during this time.
Solution: Use the QoS options in the Vanguard device to classify the FTP traffic at a lower priority and allocate less bandwidth to this traffic. Classify the billing transaction traffic and give that a higher priority with an allocation of more bandwidth. Policy-Based Routing could also be utilized to route selected traffic differently at a particular time of day. Better prioritisation of the traffic and allocation of bandwidth allows the bank to achieve fast and consistent service to their customers all hours of the day.
E-commerce
Problem: When there is high traffic to a Web site, it becomes very congested and packet loss causes unacceptable delays for customers. If customers try to place an order and have to wait, they will go to another site to order the same product.
Solution: There are a number of approaches that might be considered to handle this problem:
* Classify the billing transactions to a very high priority and bandwidth allocation.
* Classify other traffic, such as HTTP, to a very low or default priority.
* Set the bandwidth threshold appropriately so Parallel SVCs will be enabled to meet network bandwidth requirements when it is needed.
Call centre
Problem: An industrial product distributor connects their head office five remote offices. The network carries their voice call centre traffic, order transactions, e-mail and data traffic. They sometimes experience traffic congestion problems in their network.
Solution: Classify HTTP and FTP traffic at a very low priority with limited bandwidth. This results in better resource management because they combine a call centre software to re-route calls to other remote offices when the wait time exceeds a pre-determined value. They can also monitor the number of operators on line to track whether they have enough resources dedicated to answering customer inquiries and orders.
What types of applications/traffic can be improved by QoS?
Some of the biggest challenges in managing network traffic are due to the limits of latency (delay) and jitter to maintain quality Voice over IP, combined with the potential massive bursty traffic flow from File Transfer Protocol (FTP) or Hypertext Transfer Protocol (HTTP) applications, E-mail Traffic (SMTP), domain name service (DNS). Currently, about 80% of the Internet traffic is bursty HTTP and HTML-based Web Application traffic.
As users encounter busy e-commerce and Web portal sites, they become impatient and frustrated when they must wait for connection to application servers and congested links. The lost business is measured by wait times, slow transactions, or lost connections. Voice and video quality may be compromised if the internet network traffic is only able to provide "best-effort" traffic services.
QoS can assist in managing traffic of shared networks with multiple subscribers to help optimise bandwidth, multiple types of traffic, queuing latency, flow control, and access control for the prioritisation of traffic order.
How QoS maximises different applications, traffic and service classes
One approach to maximising or prioritising network users is to separate the users or applications by service classes. The network or Internet traffic can be separated into classes as it enters busy e-commerce or Web portal sites where slowdowns tend to occur. Businesses will pay for premium services if they will receive preferential treatment when they access a site. Packets from specific host addresses can be marked as they enter the site and selected particular subscribers can receive preferential priority services.
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