Lesson 4 Controlling Bandwidth

As communication within your network and with the Internet becomes more congested, network performance may deteriorate. Once you determine the source of network congestion through ISA Server reports, you can allocate different priorities to traffic through the use of bandwidth priorities and bandwidth rules. Bandwidth priorities are policy elements that designate priority values between 1 and 200 for incoming and outgoing bandwidth. These bandwidth priorities can then be applied to specific connections through the use of bandwidth rules.

After this lesson, you will be able to


Configure the effective bandwidth of a connection

Create bandwidth priorities

Create bandwidth rules


Estimated lesson time: 40 minutes

Determining Effective Bandwidth

Effective bandwidth is the actual data transfer rate available to your network clients through a particular Internet connection (for example, a dial-up connection or dedicated Internet connection). Before you create bandwidth rules, you need to specify the effective bandwidth of your Internet connection in ISA Management so that ISA Server can properly enforce bandwidth priorities.

Effective Bandwidth for Dial-up Connections

The first step in configuring effective bandwidth is to determine the maximum effective bandwidth of the connections on the ISA Server computer or array. For a modem, the bandwidth depends on the modem speed, compression, and other factors. When you configure a dial-up connection's properties to display its icon on the task bar when the connection is active, you can view the effective bandwidth by holding your mouse over that icon in the status area of the task bar.

You can specify the effective bandwidth for a dial-up connection by modifying the dial-up entry associated with that connection in ISA Management, as shown in Figure 9.16. To configure effective bandwidth for a dial-up entry in ISA Management, modify the settings on the Bandwidth tab of the dial-up entry's Properties dialog box.

Figure 9.16 Configuring effective bandwidth for a dial-up connection

Follow these steps to set effective bandwidth for an existing dial-up entry:

In the console tree of ISA Management, expand the node of the array containing the dial-up entry you want to modify, and then expand the Policy Elements node.
Click the Dial-up Entries folder.
In the details pane, right-click the applicable dial-up entry and then click Properties.

The Dial-up_entry_name Properties dialog box appears.

On the Bandwidth tab, click the Enable Bandwidth Control check box.
In the Effective Bandwidth (Kbit/Sec) text box, type the effective bandwidth for all the devices in the array.
Click OK.

Effective Bandwidth for Dedicated Network Connections

For frame relay networks (E1/T1 or E3/T3), the maximum effective bandwidth is determined by your wide area network (WAN) provider. When you configure a dedicated network connection's properties to display its icon on the task bar when the connection is active, you can view the effective bandwidth by holding your mouse over that icon in the task bar status area.

You can configure effective bandwidth for a dedicated network connection by modifying bandwidth rules properties in ISA Management, as shown in Figure 9.17.

Figure 9.17 Configuring effective bandwidth for a dedicated connection

Follow these steps to set effective bandwidth for a network card:

In the console tree of ISA Management, right-click the Bandwidth Rules folder and click Properties.

The Bandwidth Rules Properties dialog box appears.

On the General tab, click the Enable Bandwidth Control check box.
In the Effective Bandwidth (Kbit/Sec) text box, type the effective bandwidth for the network connection.
Click OK.

After you have determined the maximum bandwidth, study reports generated for peak-hour activity. Analyze how much bandwidth is actually allocated for all the requests, on both the internal card and the external card.

Configure the effective bandwidth to the lowest maximum bandwidth available for the devices on the ISA Server computer. For example, if a device used for internal communication has 100 KB effective bandwidth and the external device has 56 KB, you should configure the effective bandwidth at 56 KB.

Calculate bandwidth requirements for internal communication by considering the following types of internal communication:

Communication between computers on the local network

Cached content returned from the ISA Server computer to a computer on the local network

Communication between array members, unless you have an additional card configured for intra-array communication

Bandwidth rules are not applied when ISA Server returns cached content to an internal computer or to intra-array communication.

Configuring Bandwidth Priorities

Bandwidth priorities are policy elements that define the priority level applied to connections passing through the ISA Server computer. These policy elements are then assigned to bandwidth rules to prioritize specific connections or traffic types. Network connections without an assigned bandwidth priority have lower priority than connections with assigned priorities, and network connections with lower priorities have less of a chance to pass through ISA Server than a connection with a higher bandwidth priority.

Bandwidth priorities are specified according to the following directions:

Outbound bandwidth This is the bandwidth priority allocated for requests from internal clients for objects on the Internet.

Inbound bandwidth This is the bandwidth priority allocated for requests from external clients for objects on the local network.

The bandwidth priority can be assigned any number between 1 and 200.

ISA Server includes a built-in bandwidth priority named Default Bandwidth Priority. The Default Bandwidth Priority assigns a value of 100 to both outbound and inbound bandwidth.

You use a bandwidth priority when you create and configure bandwidth rules, which determine how much scheduling priority is allocated for specific network connections. For example, you can create a bandwidth priority called Best Access with outbound and inbound bandwidth priority set to 150. You can also create a bandwidth priority called Good Access, with outbound and inbound bandwidth set to 80. You can later use these bandwidth priorities when you configure bandwidth rules.

New bandwidth priorities are created in ISA Management by right-clicking the Bandwidth Priorities folder, pointing to New, and then clicking Bandwidth Priority, as shown in Figure 9.18. This procedure opens the New Bandwidth Priority dialog box, as shown in Figure 9.19.

When the new bandwidth priorities you create are applied to a connection, more processing is required than when the default bandwidth priority is applied.

Figure 9.18 Creating a new bandwidth priority

Figure 9.19 The New Bandwidth Priority dialog box

Follow these steps to create a bandwidth priority:

In the console tree of ISA Management, expand the node corresponding to the array for which you want to create a bandwidth priority, and then expand the Policy Elements node.
Right-click the Bandwidth Priorities folder, point to New, and then click Bandwidth Priority.

The New Bandwidth Priority dialog box appears.

In the Name text box, type the name of the bandwidth priority.
In the Description (Optional) text box, type a description for the bandwidth priority.
In the Outbound Bandwidth (1-200) text box, type a number between 1 and 200.
In the Inbound Bandwidth (1-200) text box, type a number between 1 and 200.
Click OK.

Configuring Bandwidth Rules

Bandwidth rules apply predefined bandwidth priorities to traffic passing through ISA Server. When you create a bandwidth rule, you can specify a traffic type by any combination of the following parameters:

Protocol definition

Requesting user or source IP addresses

Request Destination

Schedule

Content type

The default bandwidth rule applies the default bandwidth priority (100) to all inbound and outbound traffic. As a result, all traffic passing through ISA Server is assigned a priority of 100 unless otherwise specified.

To create a new bandwidth rule, launch the New Bandwidth Rule wizard in ISA Management by right-clicking the Bandwidth Rules folder, pointing to New, and then clicking Rule, as shown in Figure 9.20.

Figure 9.20 Creating a new bandwidth rule

Follow these steps to create a bandwidth rule:

In the console tree of ISA Management, right-click the Bandwidth Rules folder, point to New, and then click Rule.

The New Bandwidth Rule wizard opens.

In the New Bandwidth Rule wizard, follow the on-screen instructions.

Before you use the New Bandwidth Rule wizard to create a rule, be sure to create policy elements for the new rule. Depending on how you configure the rule, you may require the following policy elements: protocol definitions, schedules, client address sets, destination sets, content groups, and bandwidth priorities.

Follow these steps to configure bandwidth priority for an existing band-width rule:

In the console tree of ISA Management, click the Bandwidth Rules folder.
In the details pane, right-click the applicable bandwidth rule, and then click Properties.

The Bandwidth_rule_name Properties dialog box appears.

On the Bandwidth tab,
To use the Windows 2000 default scheduling, click the Default Scheduling Priority radio button.
To specify a priority, click the Specified Priority radio button and then in the Name drop-down list box, select a bandwidth priority to apply to the rule and type an outbound bandwidth and inbound bandwidth.

You can set the bandwidth priority either to the default scheduling priority or to a bandwidth priority you have configured. If you select the default setting, the specified communication is guaranteed a minimum network bandwidth.

Note that connections that have specific bandwidth priorities will require some additional overhead while establishing the connection.

Rule Order

Like routing rules, bandwidth rules are ordered. Each rule is assigned a specific number, with the default bandwidth rule always processed last. You can change the order of all bandwidth rules other than the default bandwidth rule.

For each bandwidth rule, ISA Server compares the parameters defined in the rule to the details of the connection. The rule numbered 1 is processed first. If the connection matches the conditions specified by the rule, the bandwidth priority of that rule is applied to the request. Otherwise, the next rule is processed. This continues until the last default rule is processed and applied to the request. For example, if the first bandwidth rule applies to UserX and has assigned an inbound and outbound bandwidth priority of 150, and the second bandwidth rule applies to all audio content and has a inbound and outbound bandwidth priority of 200, a connection in which UserX sends audio content is assigned a bandwidth priority of 150 by ISA Server. The first bandwidth rule is applied because it is the first to match the connection.

Follow these steps to change the order of a bandwidth rule:

In the console tree of ISA Management, click the Bandwidth Rule folder.
In the details pane, right-click the rule whose order you want to change, and then click Move Up or Move Down.

Move Up and Move Down are available only after there are at least three bandwidth rules listed.

Repeat as necessary to arrange the rules in the desired order.

Default Bandwidth Rule

When you install ISA Server, it configures a default bandwidth rule. The default rule assures that communication without an assigned bandwidth rule will be allocated the minimum bandwidth assured by Windows 2000 default scheduling.

The default bandwidth rule is always last in the ordered list. It cannot be modified or deleted.

Practice: Creating a Bandwidth Rule

Exercise 1: Creating a New Bandwidth Priority Policy Element

In this exercise, you create a new bandwidth priority that assigns a maximum value of 200 to both incoming and outgoing traffic.

To create a new bandwidth priority


Log on to Server1 as Administrator.
In ISA Management, expand the MyArray node, and then expand the Policy Elements node.
Right-click the Bandwidth Priorities folder, point to New, and then click Bandwidth Priority.

The New Bandwidth Priority dialog box appears.

In the Name text box, type MaxPriority.
In the Outbound Bandwidth (1-200) text box, type 200.
In the Inbound Bandwidth (1-200) text box, type 200.
Click OK.

Exercise 2: Creating a New Bandwidth Rule

In this exercise, you apply the new policy element MaxPriority to all audio and video content.

To create a new bandwidth rule


While you are still logged on to Server1 as Administrator and ISA Management is open, right-click the Bandwidth Rules folder in the console tree, point to New, and then click Rule.

The New Bandwidth Rule wizard appears.

In the Bandwidth Rule Name text box, type MaxAudioVideo.
Click Next.

The Protocols screen appears.

Leave All IP Traffic selected as the default, and then click Next.

The Schedule screen appears.

Leave Always as the default, and then click Next.

The Client Type screen appears.

Leave Any Request selected as the default, and then click Next.

The Destination Sets screen appears.

Leave All Destinations selected as the default, and then click Next.

The Content Groups screen appears.

Click the Selected Content Groups radio button.
In the list box, select the Audio check box, and then select the Video check box.
Click Next.

The Bandwidth Priority screen appears.

Click the Custom radio button.
In the Name drop-down list box, select MaxPriority.
Click Next.

The Completing the New Bandwidth Rule wizard appears.

Click Finish.

You should now be able to view the MaxAudioVideo bandwidth rule in the details pane in ISA Management.

Lesson Summary

ISA Server allows you to allocate more bandwidth to specific types of network traffic through bandwidth priorities and bandwidth rules.

Bandwidth priorities are policy elements that are assigned a value between 1 and 200 for incoming and outgoing bandwidth, with higher values representing higher priorities. Bandwidth priorities are based upon the effective bandwidth of a network connection, a figure which you must specify manually in ISA Server. Bandwidth priorities themselves are configured in ISA Management through the Policy Elements node. ISA Server includes a default bandwidth priority policy element named Default Bandwidth Priority, which assigns a value of 100 to both incoming and outgoing bandwidth.

Bandwidth rules, which are configured through the Bandwidth Rules folder in ISA Management, apply these bandwidth priorities to connection types. Connection types may be specified by associated protocol, schedule, client source, request destination, and/or content type. Bandwidth rules are ordered like routing rules, with the default rule (which assigns the default bandwidth priority to all network traffic) always processed last.