Chapter 1 Introduction

Solaris Bandwidth Manager 1.5 is a bandwidth management system that helps you manage your network resources and provide a guaranteed quality of service to users. Using it, you can:

• allocate guaranteed bandwidth to different classes of network traffic

• prioritize traffic, giving highest priority to urgent traffic

• make sure that the network is fully utilized at all times, by sending low-priority traffic when there is no urgent traffic

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.

How Bandwidth Management Works

Bandwidth is allocated to a class of network traffic. Traffic is put into classes using a set of filters. Filters are defined using some or all of the following:

• IP source address

• IP destination address

• IP protocol (TCP, UDP or other)

• Source ports for TCP and UDP

• Destination ports for TCP and UDP

• Type of Service (TOS) value

• URL or URL Group

Class definitions are hierarchical and every class has a parent. For example, if you define a class for FTP traffic and a class for FTP traffic to a host called pear, the classes are connected in a hierarchy as shown in Figure 1-1.

Figure 1-1 Hierarchical Class Definitions

In this example, the ftp class is a child of the root class and is the parent of the ftp-to-pear class.

The configuration of Solaris Bandwidth Manager specifies the set of known classes for an interface, defined in terms of the values of some or all of these factors. It also allocates a percentage of bandwidth and a priority to each class. The priority of a class is an integer from 1 (highest priority) to 7 (lowest priority).

When a packet arrives at Solaris Bandwidth Manager, the classifier analyses the packet protocol, TOS value, URL information, source information, and destination information and allocates the packet to a class queue where it waits to be processed. If the queue to which a packet is allocated is full, the packet is dropped. Normal retransmission means that the packet is resent.

The scheduler uses the percentage bandwidth configured and the priority for each class to decide the order in which class queues are processed. Within a class queue, the packets are processed on a first-in, first-out basis. When the network traffic reaches the maximum allocated to a class, packets from the next class in priority order are processed.

Figure 1-2 Bandwidth Allocation

Borrowing Bandwidth

Each class is guaranteed a percentage of the bandwidth, and when that limit is reached, normally no more traffic from that class can be forwarded. However, if the network link is not fully used, a class can borrow bandwidth temporarily from its parent class, and send traffic at a percentage that exceeds its allocation.

It is possible to set a maximum allowed bandwidth for a class--to stop it borrowing all of the available bandwidth.

The Root Class and the Default Class

The root class is a special class that is created automatically by the Solaris Bandwidth Manager policy agent. You cannot explicitly assign guaranteed bandwidth to the root class: if the total bandwidth allocated to other classes is less than 100%, the difference is allocated to the root class and is available for borrowing and for use by traffic not allocated to any other class.

The default class is an optional special class. Any packet that the classifier does not allocate to a specific class is put in the default class. The scheduler treats the default class in exactly the same way as any other class.

If you do not define a default class, any packet that the classifier does not allocate to a specific class is put in the root class.

Flows

A flow is a complete exchange of data across a network, such as a file transfer by ftp or a mail message being sent by smtp.

A flow is identified by:

• The interface used

• The IP source address

• The IP destination address

• The IP protocol (TCP, UDP or other)

• The source and destination ports (TCP and UDP)

• The IP type of service (TOS) value

• The URL

For more information on flow statistics, see "Flows". Using the Java APIs, it is possible to write an application to detect the start of a flow, or the presence of traffic in a new flow, and update the configuration to take account of that flow.

Directory Service Interaction

Solaris Bandwidth Manager configuration information and policy information can be stored in a directory service such as Sun Directory Services 3.1. Some advantages to this approach are:

• The configuration of multiple instances of Solaris Bandwidth Manager can be updated from a single point, the directory.

• The configuration can be dynamically updated upon detection of user connections or traffic flows, for example when remote access using the RADIUS protocol is in use.

In many networks, particularly where users have dial-up connections or are mobile, there is no permanent mapping between a user and an IP address. However, if a remote user connects to the network using a RADIUS login sequence when using Sun Directory Services, the user's directory entry is updated with the current IP address. Using a directory to store information about users and their current locations provides a way to identify the user who is associated with a particular IP address. This has two benefits:

• You can adjust the configuration of the classifier and scheduler depending on the actual usage of the network.

• You can collect accounting information for individual users.

See Chapter 6, Configuring Solaris Bandwidth Manager with a Directory Service for details of how Solaris Bandwidth Manager interacts with a directory service.

Support for HTTP Traffic

Most web transactions involve a proxy web server. This proxy hides the actual HTTP server from the user. Classifying web traffic based on the proxy's IP address does not provide an accurate view of the actual network traffic. Solaris Bandwidth Manager can use URLs to identify and classify web traffic.

Type of Service Control

The header of an IP packet contains a Type of Service (TOS) field. This field was originally designed to be used by the upper layers to provide information to the Internet layer to optimize the packet route. It is used in both routing and queuing algorithms.

Solaris Bandwidth Manager has two available TOS modes, TOS match and TOS mark. In TOS match mode, the TOS value is used to classify the packet. In TOS mark mode, the packet is classified using other information, and a TOS value inserted, replacing any existing TOS value. The TOS value inserted is configured for the class. TOS match and TOS match mode can be used simultaneously. In this case, the TOS value is used to classify the packet and is then overwitten with a new TOS value.

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Note -

Use of the TOS value by Solaris Bandwidth Manager is optional. See "Interface Definition" for information about setting the mode to determine whether the TOS value is used, and in which mode. If you are not using a TOS mode, the value of the TOS field is left unchanged.

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Bandwidth Statistics and Accounting

Knowing how your network is being used lets you charge accordingly. Solaris Bandwidth Manager provides two sets of statistics that you can use for accounting:

class statistics	The cumulated number of bytes per class.
flow statistics	The cumulated number of bytes per flow.

See Chapter 8, Statistics for information about how to use the statistics features in Solaris Bandwidth Manager.

New in Solaris Bandwidth Manager 1.5

Solaris Bandwidth Manager 1.5 is a follow-on release from Sun Bandwidth Allocator 1.0. It provides the following additional features:

• Regulation of incoming and outgoing traffic

• Differentiated Services/Type of Service support

• Classification of web traffic based on URLs

• Improved accounting and billing

• Ability to work with a directory service

• Dynamic configuration

• The ability to send events that can be read by a system that supports version 5 of the CISCO NetFlow protocol

• Additional and improved APIs