Bandwidth Management

The bandwidth of a network link is the maximum amount of data that can be transmitted simultaneously. Bandwidth is measured in bits per second, or more often in megabits per second (Mb/s). The maximum bandwidth of a link is determined by the devices at either end of the link, and by the type of link in use. Bandwidth is also limited by the physical characteristics of the material used on the link, but the limits of the network devices are typically the determining factor.

For an organization buying network services from a provider, higher bandwidth is usually available for a higher cost. For a network provider, higher bandwidth is available by using higher-performance network devices, typically at additional cost.

The Need for Bandwidth Management

Almost all network links are used by more than one user or application. This means that the available bandwidth has to be shared between them. Bandwidth management tools let you manage how this is done.

If a network link is continuously congested, the link needs to be upgraded to provide greater capacity. In many cases, however, the typical load on a link is within the link capacity, and the link is congested only temporarily. Temporary congestion is sometimes predictable; for example, there are typically peaks in network use at particular times of the day or following a particular event. Other causes of temporary congestion, such as the transfer of a large file, are not possible to predict.

If the average use of a link is within the link capacity, you can make considerable improvements in the performance of the network link by managing how the available bandwidth capacity is used. Allocating bandwidth to a particular type of traffic enables you to optimize the usage of the available bandwidth.

Solaris Bandwidth Manager 1.5 enables you to manage the bandwidth used by IP traffic. It does this by:

• Allocating traffic to a class based on the application type, source and destination addresses, URL group, or a combination, then assigning individual limits for each class. For example:

  • Traffic to Engineering must have at least 50% of the link.

  • HTTP traffic cannot exceed 10% of the link.

• Prioritizing traffic. Some types of traffic, for example interactive traffic generated when using telnet or rlogin, need a quick response time. Solaris Bandwidth Manager lets you assign a higher priority to that traffic. Traffic that does not require a quick response time, such as a file transfer using FTP, can be assigned a lower priority.

  By balancing the bandwidth allocated to different types of network traffic and the relative priorities, you can optimize your network performance.

Examples

• You are the owner of a LAN leasing a network connection from a service provider. You can use Solaris Bandwidth Manager to make sure you make the most efficient use of the capacity you lease. Bandwidth management makes sure that your higher-priority traffic is sent first, but that you always get the maximum use of the capacity you are paying for. It is no longer be necessary to over-specify your requirements just to guarantee that priority traffic can be sent. You might even be able to reduce the capacity you lease.

• You are the owner of a WAN providing network services to many clients. Solaris Bandwidth Manager enables you to regulate the traffic in your network. With Solaris Bandwidth Manager you can provide a guaranteed minimum of bandwidth to a client, and as a bonus, provide additional bandwidth from time to time when it is not required by other clients. Since you know the level of bandwidth guaranteed, capacity planning is be both easier and more accurate.

• You are a web service provider, hosting several web sites on behalf of commercial companies. Solaris Bandwidth Manager enables you to guarantee your client companies that a given bandwidth is available to the customers visiting their web sites. Today, many web providers' charges are based either on disk space usage or on the number of times a site is visited. Disk space used is not a good indication of the cost to the provider, since a small site that is visited frequently can be as expensive to provide as a large site that is visited less frequently. Using the number of visits to a site is a better indicator of the cost to the provider, but is potentially an unbounded cost for the client. With Solaris Bandwidth Manager you can charge clients for a guaranteed bandwidth for their web sites.

• You are an ISP providing services to many customers. Solaris Bandwidth Manager enables you to provide different classes of services to different customers. For example, you could offer Premium and Standard services, with different guaranteed minimum access levels, to suit the needs and budgets of your customers.