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.
