Manual Chapter : BIG-IP Link Controller Solutions Guide v4.5:Introducing the Link Controller

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Link Controller

  • 4.6.1, 4.6.0, 4.5 PTF-08, 4.5 PTF-07, 4.5 PTF-06, 4.5 PTF-05, 4.5 PTF-04, 4.5 PTF-03, 4.5 PTF-02, 4.5 PTF-01, 4.5.14, 4.5.13, 4.5.12, 4.5.11, 4.5.9, 4.5.0
Manual Chapter


Introducing the Link Controller

What is the BIG-IP Link Controller?

The BIG-IP Link Controller is a dedicated IP Application Switch that manages bi-directional traffic to a site across multiple links, regardless of connection type or provider. The Link Controller provides granular traffic control for Internet gateways, so that users can define how traffic is distributed across their links in a way that meets their business priorities. The Link Controller transparently monitors the availability and health of links to optimally direct traffic across the best available link.

The Link Controller includes the following features:

  • Dynamic load balancing, based on the following link attributes:

    • Total available bandwidth of the link

    • The costs of purchased incremental bandwidth segments

    • Inbound link capacity and resource limits

    • Outbound link capacity and resource limits

  • Router monitoring, to ensure high availability and continuous uptime

  • Internet Link Evaluator, to view current Internet connectivity metrics


The Link Controller is also available as a module on the BIG-IP system.


Understanding link load balancing

Link load balancing is defined as managing traffic across multiple Internet or WAN gateways. Link load balancing ensures high availability in the network, and improves the performance of a web site or data center. Link load balancing provides a method by which an organization can reliably manage a multi-homed network. A multi-homed network is composed of one or more data centers that have more than one gateway, or link, to the Internet.

As enterprises increase their reliance on the Internet for delivering mission-critical applications and services, using only one link and ISP provider to access the public network represents a single point of failure. Link Load balancing, with the BIG-IP Link Controller, removes the risk of this single point of failure by enabling enterprises to control and monitor multiple links for their Internet connectivity.

The BIG-IP Link Controller:

  • Guarantees reliable network connections and eliminates downtime by detecting any type of connection outage, and transparently directing traffic away from malfunctioning or unavailable links.

  • Distributes traffic to optimize the capacity of each connection by monitoring line throughput so that links do not become over-saturated.

  • Increases user and site performance. The BIG-IP Link Controller measures and directs users over the best performing link to increase end user and site response times.

  • Directs traffic over the least expensive link. Administrators can define the price of links and tiered pricing schemes. The BIG-IP Link Controller can direct traffic to the least expensive connection, lowering bandwidth costs.

  • Traffic control to match business priorities. Organizations can define traffic policies to direct traffic over specified connections.

  • Provides the Internet Link Evaluator, so that you can evaluate link performance, over time, to help you choose the Internet service providers that can best serve your customers.

  • Provides integrated firewall load balancing, and enables customers to double their firewall performance through intelligent traffic management to redundant firewall configurations.

Link management

With the Link Controller, you can manage both inbound and outbound traffic over multiple links. You can distribute traffic based on performance, bandwidth cost, and bandwidth availability. The metrics you can specify are the limits on bandwidth usage, and the pricing structure of your purchased bandwidth. When you specify the limits and pricing metrics for your links, the Link Controller then load balances the links based on those metrics.

Link monitoring

You can monitor several aspects of your managed links using the following tools:

  • Link Statistics
    The Link Statistics screen, in the Configuration utility, displays information about the status, bandwidth usage, bandwidth limits, and bandwidth costs for each of the links managed by the Link Controller.
    For more information on link statistics, review Chapter 16, Working with Link Configuration , in the BIG-IP Reference Guide.

  • Internet Link Evaluator
    The Internet Link Evaluator shows the average round trip times, completion rates, and router hops over the links managed by the Link Controller for any of the seven continents. You can use the Internet Link Evaluator to determine which links best serve a particular global region. You can also use the Internet Link Evaluator to compare link performance to a particular global region.
    For more information on the Link Evaluator, review Chapter 15, Internet Link Evaluator , in the BIG-IP Reference Guide.

  • Transparent monitoring
    Transparent monitoring provides the health status of the routers for the managed links.

What's new in version 4.5

The following features and enhancements are part of the version 4.5 release.

New configuration screens

In version 4.5, the Configuration utility now includes screens designed for quick and simple link configuration. You can use the screens for your initial setup, and to later refine your configuration using the advanced properties screens. For more information on working with the new link configuration screens, see Chapter 16, Working with Link Configuration, in the BIG-IP Reference Guide.


Full duplex billing support

With this version of the BIG-IP Link Controller, you can configure full duplex billing support if that is the billing method that your Internet service providers (ISPs) use. When you enable full duplex billing support, the Link Controller manages and reports on the link traffic based on the peak usage of ingress or egress bandwidth, whichever is higher. If duplex billing is not enabled, the controller manages and reports on link traffic based on the combined total of ingress and egress bandwidth usage. For more information, see Chapter 16, Working with Link Configuration , in the BIG-IP Reference Guide.


Security enhancements

You can now use the Setup utility to configure a remote LDAP or RADIUS authentication server. With this feature, you no longer need to directly edit configuration files to set up your LDAP or RADIUS authentication server.

Also, this release of the BIG-IP Link Controller expands the number of user roles that you can assign to user accounts for the purpose of user authorization. In addition to the standard Full Read/Write, Partial Read/Write, and Read-Only access levels, you can now define which user interface an administrator uses to access the BIG-IP system (the Configuration utility, the command line interface, or the iControl interface). These user authorization roles are stored in the local LDAP database on the BIG-IP system and are designed to operate in concert with centralized LDAP and RADIUS authentication.

For details on the Setup utility features, see Chapter 2, Using the Setup Utility, in the BIG-IP Reference Guide. For details on the new user accounts, see Chapter 17, Administering the BIG-IP System , in the BIG-IP Reference Guide.


Billing estimates based on P95 bandwidth usage

The Link Statistics screens now include a Billing Estimate screen, where you can enter date ranges and view your actual link bandwidth usage compared to your purchased bandwidth. For details on the Billing Estimate screen, review the online help for that screen. To view the Billing Estimate screen, from the navigation pane, expand the Link Statistics item, and then click P95.

Easy system account creation

With this release, the BIG-IP system now offers a centralized Setup screen to set the passwords for the three system accounts: root, admin, and support. For the support account, you can also specify whether to allow command line access, Web access, or both.

For more information on managing system accounts, see Chapter 17, Administering the BIG-IP System , in the BIG-IP Reference Guide.