Manual Chapter : BIG-IP Administrator guide v3.1: Introduction to the Administrator Guide

Applies To:

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BIG-IP versions 1.x - 4.x

  • 3.1.1 PTF-01, 3.1.1, 3.1.0
Manual Chapter


Introduction to the BIG/ip Controller Administrator Guide

Welcome to the BIG/ip Controller Administrator Guide

Welcome to the BIG/ip® Controller Administrator Guide. This guide describes the advanced features included in the BIG/ip Controller. The Administrator guide also includes the software specifications for the BIG/ip Controller platform and reviews some sample configurations that can help you in planning your own configuration. This book is a part of a series of three guides:

  • BIG/ip Controller Getting Started Guide
    Use this guide for hardware configuration and basic software configuration.
  • BIG/ip Controller Administrator Guide
    Use this guide for advanced software configuration and administration of the BIG/ip Controller.
  • BIG/ip Controller Reference Guide
    Use this guide for reference information including the BIG/pipe command line commands, BIG/ip configuration utilities, and system utilities.

BIG/ip Controller specifications

The BIG/ip Controller is a network appliance that manages and balances traffic for networking equipment such as web servers, cache servers, routers, firewalls, and proxy servers. A variety of useful features meets the special needs of e-commerce sites, Internet service providers, and managers of large intranets. The system is highly configurable, and its web-based and command line configuration utilities allow for easy system set up and monitoring.

Adding a BIG/ip Controller to your network ensures that your network remains reliable. The BIG/ip Controller continually monitors the servers and other equipment it manages, and never attempts to send connections to servers that are down or too busy to handle the connection. The BIG/ip Controller uses a variety of methods to monitor equipment, from simple pings to more advanced methods, such as Extended Content Verification that verifies whether a server returns specific site content. The BIG/ip Controller also offers several layers of redundancy that ensure its own reliability.

Internet protocol and network management support

The BIG/ip platform supports both TCP and UDP protocols, and also supports popular network services including:

  • HTTP
  • SSL
  • FTP (active and passive)
  • SMTP
  • NNTP
  • POP
  • DNS
  • IMAP
  • Real Audio/TCP
  • Telnet

    The BIG/ip Controller supports administrative protocols, such as Simple Network Management Protocol (SNMP) and Simple Mail Transfer Protocol (SMTP) (outbound only), for performance monitoring and notification of system events. The BIG/ip Controller's SNMP agent allows you to monitor status and current traffic flow using popular network management tools, including the F5 Configuration utility. The SNMP agent provides useful data such as packets in and out per second, and current connections being handled for each virtual server. You may also want to take advantage of Telnet, FTP, and the F-Secure SSH client (distributed only in the US). The F-Secure SSH client provides a secure UNIX shell connection to the BIG/ip Controller from a remote workstation.

Security features

The BIG/ip Controller offers a variety of security features that protect both the controller itself, and the network equipment that it manages. Each of the following features can help prevent potentially hostile attacks on your site or equipment.

  • IP address protection
    On its external network, the BIG/ip Controller does not expose the IP addresses of the servers that it manages unless you specifically configure it to do so. Instead, it offers firewall capabilities, translating addresses when servers connect to other hosts on the external network. You can set up either standard Network Address Translations (NATs) that allow both incoming and outgoing traffic, or you can set up Secure Network Address Translations (SNATs) that allow only outgoing connections.
  • Port lockdown
    The BIG/ip Controller prevents clients from connecting to any port which you have not specifically opened for network traffic. This feature helps prevent a common attack where users try to gain access to the machine using one of the many ephemeral ports that do not host a well-known service.
  • Controlled administrative connections
    The BIG/ip Controller allows you to make direct administrative connections to the servers it manages, but it prevents direct connections to those servers by random clients, based on their IP address.
  • IP address filtering
    The IP filtering features allow you to specifically accept or deny connections received from particular IP addresses or ranges of IP addresses.
  • Termination of inactive connections
    The BIG/ip Controller automatically terminates connections that remain inactive for a period of time you specify, which prevents common denial of service attacks.

    In addition to these features, BIG/ip Controllers distributed in the US support encrypted administrative connections using F-Secure SSH for shell connections, and SSL protocol for connections to the web-based configuration utility.

Configuration scalability

The BIG/ip Controller is a highly scalable and versatile solution. You can actually configure a single BIG/ip Controller to manage thousands of virtual servers, though most common configurations are significantly smaller. The number of servers, firewalls, or routers that a single BIG/ip Controller can load balance is limited only by the capacity of your network media, such as Ethernet. The BIG/ip Controller supports a variety of media options, including Fast Ethernet, Gigabit Ethernet, and FDDI. The maximum number of concurrent connections that a BIG/ip Controller can manage is determined by the amount of RAM in your particular BIG/ip Controller hardware configuration.

Configuration and monitoring tools

The BIG/ip platform provides the following web-based and command line administrative tools that make for easy setup and configuration.

The First-Time Boot utility

The First-Time Boot utility is a wizard that walks you through the initial system set up. The utility helps you quickly define basic system settings, such as a root password and the IP addresses for the interfaces that connect the BIG/ip Controller to the network. The First-Time Boot utility also helps you configure access to the BIG/ip web server, which hosts the web-based F5 Configuration utility.

The F5 Configuration utility

The F5 Configuration utility is a web-based application that you use to configure and monitor the load balancing setup on the BIG/ip Controller. In the F5 Configuration utility, you can configure virtual servers, define IP and rate filters, and also configure system objects including the SNMP agent and system settings. The F5 Configuration utility allows you to monitor network traffic, current connections, and the operating system itself, and it also provides convenient access to downloads such as the SNMP MIB. The F5 Configuration utility requires Netscape Navigator version 4.06 or later, or Microsoft Internet Explorer version 4.0 or later.

The BIG/pipe and BIG/top command line utilities

The BIG/pipeTM utility is the command line counter-part to the F5 Configuration utility. Using BIG/pipe commands, you can configure virtual servers, open ports to network traffic, and configure a wide variety of features. To monitor the BIG/ip Controller, you can use certain BIG/pipe commands, or you can use the BIG/topTM utility, which provides real-time system monitoring. You can use the command line utilities directly on the BIG/ip Controller, or you can execute commands via a remote shell, such as the SSH client (US only), or a Telnet client.

Load balancing options

The BIG/ip Controller offers many different load balancing modes, including static and dynamic modes. A load balancing mode defines, in part, the logic that a BIG/ip Controller uses to determine which server should receive a particular connection on a specific port.

Static load balancing

Static load balancing is based on pre-defined user settings, and does not take current performance into account. The BIG/ip Controller supports three static load balancing modes:

  • Round Robin
    Round Robin mode is a basic load balancing mode that distributes connections evenly across all server ports, passing each new connection to the next server port in line.
  • Ratio
    The Ratio mode distributes new connections across server ports in proportion to a user-defined ratio. For example, if your array contained one new, high-speed server and two older servers, you could set the ratio so that the high-speed server receives twice as many connections as either of the two older servers.
  • Priority
    The Priority mode distributes connections in round robin fashion to a specific groups of servers. It begins distributing new connections to the highest priority group. If all servers in that group should go down, it begins distributing connections to servers in the next higher priority group.

Dynamic load balancing

Dynamic load balancing modes use current performance information from each node to determine which node should receive each new connection. The different dynamic load balancing modes incorporate different performance factors:

  • Least Connections
    In Least Connections mode, the BIG/ip Controller sends each new connection to the node that currently hosts the fewest current connections.
  • Fastest
    In Fastest mode, the BIG/ip Controller sends each new connection to the node that has the best response time.
  • Observed
    In Observed mode, the BIG/ip Controller sends each new connection to the node that has the highest performance rating, based on a combination of fewest connections and best response time.
  • Predictive
    Predictive mode factors in both performance ratings and performance improvement over time.

IP packet filtering, rate classes, and rate filters

The BIG/ip platform supports easy configuration of IP packet filtering. IP packet filtering allows you to control both in-bound and out-bound network traffic. For example, you can specify a single IP address, or a range of IP addresses, from which your site either accepts or denies network traffic. You can also specify one or more IP addresses to which you specifically want to allow or prevent out-bound connections.

The BIG/ip platform also supports rate classes, which are an extension to IP filters. A rate class defines a maximum outgoing packet rate (bits per second) for connections that are destined for a specific IP address or from a range of IP addresses. You can use rate classes to help control the amount and flow of specific network traffic. For example, you can offer faster connection speeds for high priority connections, such as paying customers on an e-commerce site.

Configurable persistence for e-commerce and dynamic content sites

Some e-commerce and other dynamic content sites occasionally require returning users to go the same server that hosted their last connection, rather than being load balanced to a random server. For example, if a customer reserves an airline ticket and holds it for 24 hours, the customer may need to return to a specific back-end server that stores the reservation information in order to purchase the ticket.

The BIG/ip Controller offers a variety of sophisticated persistence options that support this functionality. In addition to simple persistence and standard SSL persistence, the BIG/ip Controller supports cookie persistence. Cookie persistence is a unique implementation where the BIG/ip Controller stores persistence connection information in a cookie on the client, rather than in a table in its own memory. When the client returns and makes a persistence connection request, the BIG/ip Controller uses the information in the cookie to determine which back-end server should host the client connection.

The BIG/ip Controller supports other useful persistence options, including simple persistence for TCP and UDP (which bases connection information on source and destination IP address) and SSL persistence (which bases connection information on an SSL session ID).

BIG/ip Controller platform options

The BIG/ip Controller platform offers three different systems, each of which can be stand-alone, or can run in redundant pairs:

  • The BIG/ip LB Controller
    The BIG/ip LB Controller provides basic load balancing features. Note that the BIG/ip LB Controller does not support all of the features documented in this guide.
  • The BIG/ip HA Controller
    In addition to the basic load balancing features supported on the BIG/ip LB Controller, the BIG/ip HA Controller supports advanced features, such as Extended Content Verification, and also supports high-end security for administrative shell connections. BIG/ip HA Controllers distributed in the US also support encrypted administrative connections using SSH for shell connections and SSL for connections to the web-based F5 Configuration utility.
  • The BIG/ip HA+ Controller
    The BIG/ip HA+ Controller supports the same features as the BIG/ip HA Controller, but it offers high-end hardware for high traffic sites.

Note: BIG/ip Controllers distributed outside of the United States, regardless of system type, do not support encrypted communications. They do not include the F-Secure SSH client, nor do they support SSL connections to the BIG/ip web server. Instead, you can use the standard Telnet, FTP, and HTTP protocols to connect to the unit and perform administrative functions.

Finding help and technical support resources

In addition to this administrator guide, you can find technical documentation about the BIG/ip Controller in the following locations:

  • Release notes
    The release note for the current version of the BIG/ip Controller is available from web server on the BIG/ip Controller. The release note contains the latest information for the current version, including a list of new features and enhancements, a list of fixes, and, in some cases, a list of known issues.
  • Online help for BIG/ip Controller features
    You can find help online in three different locations:
    • The web server on the BIG/ip Controller has a PDF version of this administrator guide. Note that some BIG/ip Controller upgrades replace the online Getting Started Guide, Administrator Guide, and Reference Guide with updated versions.
    • The web-based F5 Configuration utility has online help for each screen. Simply click the Help button in the toolbar.
    • Individual BIG/pipe commands have online help, including command syntax and examples, in standard UNIX man page format. Simply type the command followed by the question mark option (-?), and the BIG/ip Controller displays the syntax and usage associated with the command.
  • Third-party documentation for software add-ons
    The web server on the BIG/ip Controller contains online documentation for all third-party software included with the BIG/ip Controller, such as GateD.
  • Technical support via the World Wide Web
    The F5 Networks Technical Support web site,, provides the latest technical notes, answers to frequently asked questions, updates for administrator guides (in PDF format), and the AskF5 natural language question and answer engine. To access this site, you need to obtain a customer ID and a password from the F5 Help Desk.

What's new in version 3.1

The BIG/ip Controller offers the following major new features in version 3.1, in addition to many smaller enhancements.

SSL Accelerator

You can configure the SSL Accelerator feature to act as a gateway SSL traffic to your content servers. The SSL Accelerator feature allows the BIG/ip Controller to accept HTTPS connections (HTTP over SSL), connect to a web server, retrieve the page, and then send the page to the client.

A key component of the SSL Accelerator feature is that the BIG/ip Controller can retrieve the web page using an unencrypted HTTP request to the content server. With the SSL Accelerator feature, you can configure an SSL gateway on the BIG/ip Controller that decrypts HTTP requests that are encrypted with SSL. Decrypting the request offloads SSL processing from the servers to the BIG/ip Controller. This also allows the BIG/ip Controller to use the header of the HTTP request to intelligently control how the request is handled.

For information about using the SSL Accelerator feature, see Chapter 4, Configuring an SSL Accelerator.

Pool Persistence

With this version of the BIG/ip Controller, persistence settings are configured at the pool level instead of the virtual server level. A pool configured with persistence settings can be referenced by a rule. This simplifies and increases the granularity of persistence configuration. For information about using Pool Persistence, see Chapter 6, Working with Advanced Persistence Options.

HTTP header rule variable

This version of the BIG/ip Controller supports a new rule variable that evaluates to the string following a user specified HTTP header tag. Header tags are not case sensitive. For information about using this variable, see HTTP request string variables, on page 3-12.

Contains rule operator

This version of the BIG/ip Controller supports a new contains rule string operator that returns True if the right hand operand is a substring of the left hand operand. This operator requires less processing than the equivalent matches_regex operation. For information about using this variable, see Variable operands (variables), on page 3-10.

New load balancing methods

This version of the BIG/ip Controller supports the new observed_member and predictive_member load balancing methods. Like the node address observed and predictive methods, the new methods use configuration that is dynamically calculated for each node address based on current connection count and inter-packet delta time. However, the new methods store load balancing state in the member "ripeness" element. This allows the new methods to load balance correctly even when multiple node servers have the same node address.

Enhancements to configuration and monitoring tools

With this release, various enhancements were made to the F5 Configuration utility, the BIG/pipe command line utility, and the BIG/ip Controller SNMP MIBs.

Enhancements to the F5 Configuration utility

The web-based F5 Configuration utility for the BIG/ip Controller, version 3.1 contains the following enhancements:

  • SSL Proxy
    Added support for the SSL Proxy feature. To access the SSL Gateway feature in the F5 Configuration utility, click the SSL Proxies icon.
  • Pool Persistence
    Persistence can now be configured for Pools, and thereby rules. The persistence settings previously were available on the Global Virtual Port Property Page, the Virtual Server Property Page, or the Virtual Servers Application Persistence Page. Now, all persistence values are located on the new Persistence Property page which can be accessed from the Pool Properties page and the Virtual Server Properties page.
  • Transparent Node mode
    The bonfire compatibility mode toggle is gone. The BIG/ip Controller is always running in this mode.
  • NIC Status
    A NIC Status field was added to the NIC list page. This field shows the whether the NIC is active, has no-carrier, or is not available.
  • Blank IP masks
    Masks that are turned off show up as blank in the UI instead of as

BIG/pipe command line utility

The BIG/pipe® command line utility has been updated and streamlined. In addition to new commands for new features, certain existing commands support new syntax to make for more efficient configuration.


The BIG/ip Controller includes an updated SNMP MIB that supports the new features, as well as enhanced support for existing features.