Web Sites With Quality-of-Service Information

The Differentiated Services Working Group of the IETF maintains a web site with links to Diffserv Internet drafts at http://www.ietf.org/html.charters/diffserv-charter.html.

Router manufacturers such as Cisco Systems and Juniper Networks provide information on their corporate web sites that describes how Differentiated Services are implemented in their products.

IPQoS Man Pages

IPQoS documentation includes the following man pages:

• ipqosconf(1M) - Describes the command for setting up the IPQoS configuration file

• ipqos(7ipp) - Describes the IPQoS implementation of the Diffserv architectural model

• ipgpc(7ipp) - Describes the IPQoS implementation of a Diffserv classifier

• tokenmt(7ipp) - Describes the IPQoS tokenmt meter

• tswtclmt(7ipp) - Describes the IPQoS tswtclmt meter

• dscpmk(7ipp) - Describes the DSCP marker module

• dlcosmk(7ipp) - Describes the IPQoS 802.1D user-priority marker module

• flowacct(7ipp)- Describes the IPQoS flow-accounting module

• acctadm(1M) - Describes the command that configures the Solaris extended accounting facilities. The acctadm command includes IPQoS extensions.

Providing Quality of Service With IPQoS

IPQoS features enable Internet service providers (ISPs) and application service providers (ASPs) to offer different levels of network service to customers. These features enable individual companies and educational institutions to prioritize services for internal organizations or for major applications.

Implementing Service-Level Agreements

If your organization is an ISP or ASP, you can base your IPQoS configuration on the service-level agreement (SLA) that your company offers to its customers. In an SLA, a service provider guarantees to a customer a certain level of network service that is based on a price structure. For example, a premium-priced SLA might ensure that the customer receives highest priority for all types of network traffic 24 hours per day. Conversely, a medium-priced SLA might guarantee that the customer receives high priority for email only during business hours. All other traffic would receive medium priority 24 hours a day.

Assuring Quality of Service for an Individual Organization

If your organization is an enterprise or an institution, you can also provide quality-of-service features for your network. You can guarantee that traffic from a particular group or from a certain application is assured a higher or lower degree of service.

Introducing the Quality-of-Service Policy

You implement quality of service by defining a quality-of-service (QoS) policy. The QoS policy defines various network attributes, such as customers' or applications' priorities, and actions for handling different categories of traffic. You implement your organization's QoS policy in an IPQoS configuration file. This file configures the IPQoS modules that reside in the Solaris OS kernel. A host with an applied IPQoS policy is considered an IPQoS-enabled system.

Your QoS policy typically defines the following:

• Discrete groups of network traffic that are called classes of service.

• Metrics for regulating the amount of network traffic for each class. These metrics govern the traffic-measuring process that is called metering.

• An action that an IPQoS system and a Diffserv router must apply to a packet flow. This type of action is called a per-hop behavior (PHB).

• Any statistics gathering that your organization requires for a class of service. An example is traffic that is generated by a customer or particular application.

When packets pass to your network, the IPQoS-enabled system evaluates the packet headers. The action that the IPQoS system takes is determined by your QoS policy.

Tasks for designing the QoS policy are described in Planning the Quality-of-Service Policy.

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:

• What are the traffic problem areas for your local network?

• What must you do to achieve optimum use of available bandwidth?

• What are your site's critical applications, which must be given highest priority?

• Which applications are sensitive to congestion?

• What are your less critical applications, which can be given a lower priority?

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:

• Popular applications such as email and outgoing FTP to a particular server, either of which could constitute a class. Because employees constantly use these applications, your QoS policy might guarantee email and outgoing FTP a small amount of bandwidth and a lower priority.

• An order-entry database that needs to run 24 hours a day. Depending on the importance of the database application to the enterprise, you might give the database a large amount of bandwidth and a high priority.

• A department that performs critical work or sensitive work, such as the payroll department. The importance of the department to the organization would determine the priority and amount of bandwidth you would give to such a department.

• Incoming calls to a company's external web site. You might give this class a moderate amount of bandwidth that runs at low priority.