System Administration Guide: IP Services

Improving Network Efficiency With IPQoS

IPQoS contains features that can help you make network performance more efficient as you implement quality of service. When computer networks expand, the need also increases for managing network traffic that is generated by increasing numbers of users and more powerful processors. Some symptoms of an overused network include lost data and traffic congestion. Both symptoms result in slow response times.

In the past, system administrators handled network traffic problems by adding more bandwidth. Often, the level of traffic on the links varied widely. With IPQoS, you can manage traffic on the existing network and help assess where, and whether, expansion is necessary.

For example, for an enterprise or institution, you must maintain an efficient network to avoid traffic bottlenecks. You must also ensure that a group or application does not consume more than its allotted bandwidth. For an ISP or ASP, you must manage network performance to ensure that customers receive their paid-for level of network service.

How Bandwidth Affects Network Traffic

You can use IPQoS to regulate network bandwidth, the maximum amount of data that a fully used network link or device can transfer. Your QoS policy should prioritize the use of bandwidth to provide quality of service to customers or users. The IPQoS metering modules enable you to measure and control bandwidth allocation among the various traffic classes on an IPQoS-enabled host.

Before you can effectively manage traffic on your network, you must answer these questions about bandwidth usage:

Using Classes of Service to Prioritize Traffic

To implement quality of service, you analyze network traffic to determine any broad groupings into which the traffic can be divided. Then, you organize the various groupings into classes of service with individual characteristics and individual priorities. These classes form the basic categories on which you base the QoS policy for your organization. The classes of service represent the traffic groups that you want to control.

For example, a provider might offer platinum, gold, silver, and bronze levels of service, available at a sliding price structure. A platinum SLA might guarantee top priority to incoming traffic that is destined for a web site that the ISP hosts for the customer. Thus, incoming traffic to the customer's web site could be one traffic class.

For an enterprise, you could create classes of service that are based on department requirements. Or, you could create classes that are based on the preponderance of a particular application in the network traffic. Here are a few examples of traffic classes for an enterprise: