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Manual Chapter: Managing Traffic with Bandwidth Controllers
Manual Chapter
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Overview: Bandwidth control management

Fine-grained bandwidth control is essential to service providers, large enterprises, and remote access services (RAS) solutions. Bandwidth controllers on the BIG-IP system can scale easily, work well in a distributed environment, and are easy to configure for various networks. Depending on the type of policy you configure, you can use bandwidth controllers to apply specified rate enforcement to traffic flows or mark traffic that exceeds limits.

Bandwidth control policies can be static or dynamic. Through the user interface (browser or tmsh command-line utility), when you apply a bandwidth control policy to a virtual server, packet filter, or route domain, you can apply only one policy at a time, and that is a static policy. Using iRules, you can combine static and dynamic bandwidth control policies up to eight policies on a connection, but only one of the eight policies can be a dynamic policy. A packet is transmitted only when all the attached policies allow it. The system as a whole supports a maximum of 1024 policies.

Bandwidth controllers vs. rate shaping

Bandwidth controller is the updated version of rate shaping on the BIG-IP system. These features are mutually exclusive. You can configure and use either rate shaping or bandwidth controllers, but not both. Bandwidth controllers include distributed control, subscriber fairness, and support for a maximum rate of 320 Gbps. Rate shaping is hierarchical and supports minimum bandwidth (committed information rate), priority, and flow fairness.

About static bandwidth control policies

A static bandwidth control policy controls the aggregate rate for a group of applications or a network path. It enforces the total amount of bandwidth that can be used, specified as the maximum rate of the resource you are managing. The rate can be the total bandwidth of the BIG-IP device, or it might be a group of traffic flows.

Task summary for creating a static bandwidth control policy

This procedure includes the steps for assigning a static bandwidth control policy to traffic, using a virtual server. Alternatively, you can assign a static bandwidth control policy to a packet filter or a route domain.

Task list

Creating a static bandwidth control policy

You can create a static bandwidth control policy to limit the bandwidth that traffic uses on the BIG-IP system.
  1. On the Main tab, click Acceleration > Bandwidth Controllers.
  2. Click Create.
  3. In the Name field, type a name for the bandwidth control policy.
  4. In the Maximum Rate field, type a number and select the unit of measure to indicate the total throughput allowed for the resource you are managing. The number must be in the range from 1 Mbps to 320 Gbps. This value is the amount of bandwidth available to all the connections going through this static policy.
  5. Click Finished.
For the bandwidth control policy to take effect, you must apply the policy to traffic, using a virtual server, packet filter, or route domain.

Adding a static bandwidth control policy to a virtual server

Adding a static bandwidth control policy to a virtual server is one way to apply the policy to traffic. Alternatively, you can add the bandwidth control policy to a packet filter or a route domain.
  1. On the Main tab, click Local Traffic > Virtual Servers. The Virtual Server List screen opens.
  2. Click the name of the virtual server you want to modify.
  3. From the Configuration list, select Advanced.
  4. From the Bandwidth Controller list, select a bandwidth control policy. Only static bandwidth control policies are available in this list.
  5. Click Update to save the changes.
The BIG-IP system now applies rate enforcement to the traffic intercepted by this virtual server, according to the static bandwidth policy you selected. A static bandwidth policy associated with a virtual server applies only to client-initiated flows, and not to bandwidth for traffic flowing toward the client.

About dynamic bandwidth control policies

You can create dynamic bandwidth control policies to restrict bandwidth usage per subscriber or group of subscribers, per application, per network egress link, or any combination of these. A dynamic bandwidth control policy provides fairness on traffic flows, according to configurable parameters, within an upper bandwidth limit. The BIG-IP system activates the dynamic bandwidth control policy for each user only when the user participates. When you create a dynamic bandwidth control policy, it acts as a policy in waiting, until the system detects egress traffic that matches the traffic you want to control and creates an instance of the policy. At that moment, the system applies the bandwidth control policy limits, as specified. No bandwidth control occurs until the system detects traffic and creates an instance of the policy. With this feature, an Internet service provider (ISP) can create and revise a single policy that can apply to millions of users.

The BIG-IP system can enforce multiple levels of bandwidth limits through the dynamic policy. For example, a user could be limited by the maximum rate, a per user rate, and a per category rate (such as for an application), all from the same dynamic policy. When the total of the maximum user rate for all the instances exceeds the maximum rate specified in the dynamic policy, the BIG-IP system maintains fairness among all users and spreads the limitation equally among users belonging to a dynamic policy.

You can also configure a dynamic bandwidth control policy to mark packets that exceed the maximum per-user rate for a specified session. The WAN router should handle the marked packets. The BIG-IP system passes packets that conform to the maximum per-user rate without marking them. You configure marking by using the IP Type of Service or Link Quality of Service setting. For example, a common use of QoS marking is for Voice over IP (VoIP) traffic. VoIP is usually assigned to the Expedited Forwarding (EF) class by using the DSCP value of 46, thus prioritized according to importance and sensitivity to loss/latency.

Alternatives for identifying users and applying dynamic bandwidth control policies to traffic are using iRules, Policy Enforcement Manager, or Access Policy Manager.

Task summary for creating a dynamic bandwidth control policy

Before you create a dynamic bandwidth control policy, F5 recommends that you select the Source Address for the CMP Hash setting on the VLAN properties screen for the VLAN that carries the traffic you want to manage. The BIG-IP system uses source and destination hashes to control the way incoming traffic is distributed among the instances of the Traffic Management Microkernel (TMM) service. Subscriber-based bandwidth control depends on having a unique one-to-one relationship between bandwidth control policy and subscriber. Subscribers are commonly identified using a unique IP address, and, therefore, load distribution among the instances of TMM service must use the source IP address as the key.

This screen snippet highlights the proper setting.

CMP Hash setting for dynamic bandwidth control CMP Hash setting for dynamic bandwidth control

This procedure describes the steps for attaching a dynamic bandwidth control policy to a traffic flow, and then applying the policy to traffic, using a virtual server. For information about using Policy Enforcement Manager to implement the policy, refer to the F5 documentation for Policy Enforcement Manager.

Task list

Creating a dynamic bandwidth control policy

You can create a dynamic bandwidth control policy to shape the traffic to which you apply the policy.
  1. On the Main tab, click Acceleration > Bandwidth Controllers.
  2. Click Create.
  3. In the Name field, type a name for the bandwidth control policy.
  4. In the Maximum Rate field, type a number and select the unit of measure to indicate the total throughput allowed for all the instances created for this dynamic policy. The number must be in the range from 1 Mbps to 320 Gbps.
  5. From the Dynamic list, select Enabled. The screen displays additional settings.
  6. In the Maximum Rate Per User field, type a number and select the unit of measure to indicate the most bandwidth that each user or session associated with the bandwidth control policy can use. The number must be in the range from 1 Mbps to 2 Gbps.
  7. From the IP Type of Service list, select Specify and type a number between 0 and 63 to assign a Type of Service (ToS) level to packets that exceed the maximum per-user rate. If you do not want to set a ToS level, maintain the default setting, Pass Through.
  8. From the Link Quality of Service list, select Specify and type a number between 0 and 7 to assign a Quality of Service (QoS) level to packets that exceed the maximum per-user rate. If you do not want to set a QoS level, maintain the default setting, Pass Through.
  9. In the Categories field, add up to eight categories of traffic that this bandwidth control policy manages. All the categories share the specified bandwidth, in accordance with the rate specified for each category.
    Note: Use the Categories setting only if you have not set values for the IP Type of Service or the Link Quality of Service setting.
    1. In the Category Name field, type a descriptive name for the category.
    2. In the Max Category Rate field, type a value to indicate the most bandwidth that this category of traffic can use, and select the unit of measure from the list, or select % and type a percentage from 1 to 100. If you specify a rate, the number must be in the range from 500 Kbps to the rate specified for the Maximum Rate Per User setting. A percentage indicates that this category can use up to the specified percentage of the maximum per-user rate. These values are upper limits (not minimum or guaranteed), so the sum can exceed the value you specified for the Maximum Rate Per User setting.
    3. Click Add to add the category to the Categories list.
    4. Repeat these steps to add more categories, up to a maximum of eight.
  10. Click Finished.
For the dynamic bandwidth control policy to take effect, you must attach the policy to a traffic flow, and then apply the policy to traffic, using a virtual server, Policy Enforcement Manager, or Access Policy Manager.

Creating an iRule for a dynamic bandwidth control policy

To implement a dynamic bandwidth control policy, you can use iRules to attach the policy to a user.
Note: For complete and detailed information iRules syntax, see the F5 Networks DevCentral web site (http://devcentral.f5.com).
  1. On the Main tab, click Local Traffic > iRules. The iRule List screen opens, displaying any existing iRules.
  2. Click Create. The New iRule screen opens.
  3. In the Name field, type a unique name between 1 and 31 characters for the iRule.
  4. In the Definition field, type the syntax for the iRule using Tool Command Language (Tcl) syntax. For example, to apply the dynamic bandwidth policy dynamic_bwc_policy200 to a user session, type the following iRule, where set mycookie defines a user session. A session is a combination of client IP address and port. when CLIENT_ACCEPTED { set mycookie [IP::remote_addr]:[TCP::remote_port] BWC::policy attach dynamic_bwc_policy200 $mycookie }
  5. Click Finished. The new iRule appears in the list of iRules on the system.
You have now identified the user for a dynamic bandwidth control policy.
You must then apply the iRule to the virtual server that intercepts the traffic you want to manage.

Adding a dynamic bandwidth control policy to a virtual server

After you attach a dynamic bandwidth control policy to a user, using iRules, you must apply the policy to traffic by adding the iRule to a virtual server.
  1. On the Main tab, click Local Traffic > Virtual Servers. The Virtual Server List screen opens.
  2. Click the name of the virtual server you want to modify.
  3. On the menu bar, click Resources.
  4. In the iRules area, click Manage.
  5. From the Available list, select the name of the iRule that you want to assign, and using the Move button, move the name to the Enabled list.
  6. Click Finished.
The BIG-IP system now manages bandwidth for the traffic intercepted by this virtual server, according to the dynamic bandwidth policy specified in the assigned iRule.

Example of a dynamic bandwidth control policy

This screen is an example of a dynamic bandwidth control policy that might be created by an Internet service provider (ISP) to manage individual mobile subscribers.

Example of completed dynamic bandwidth control policy screen Example of completed dynamic bandwidth control policy screen

In the example, the ISP sets the maximum bandwidth at 200 Mbps. Of that bandwidth, a maximum of 20 Mbps is allocated to each user. Of that allocation, application traffic is apportioned, as follows.

  • 50% applies to browser traffic (HTTP)
  • 20% applies to P2P
  • 4 Mbps applies to video
  • 1 Mpbs applies to Voice over IP (VoIP)

To activate this policy, the ISP needs to create an iRule to attach the policy to a user session, and then apply the policy to a virtual server.

The bandwidth controller is only an enforcer. For a dynamic bandwidth control policy, you also need iRules, Policy Enforcement Manager, or Access Policy Manager to identify a flow and map it to a category.

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