Networking: Concepts

In Microsoft Internet Security and Acceleration (ISA) Server 2006, a network is a rule element, which can contain one or more ranges of Internet Protocol (IP) addresses. Networks include one or more computers, typically corresponding to a physical network. You can apply rules to one or more networks, or to all addresses except those in the specified network.

For ISA Server Enterprise Edition, you can create array-level networks and enterprise networks. Array-level networks are used in the scope of a specific array, whereas enterprise networks can be used by any array in the enterprise.

Each network adapter on the computer (for ISA Server Standard Edition) or on the array members (for ISA Server Enterprise Edition) can be mapped to a single network. A network can include addresses associated with one or more network adapters. A network also determines whether Firewall clients and Web Proxy clients are supported on the network.

ISA Server 2006 includes network templates, which correspond to common network topologies. You can use the network templates to configure the firewall policy for traffic between networks.

For more information about ISA Server networking concepts, see the document Networking Concepts in ISA Server at ISA Server Guidance. (


Using Web chaining rules, you can conditionally route requests, depending on the destination. For example, requests can be routed directly to the Internet, or to a different ISA Server computer in another branch.

For Firewall clients, you can use firewall chaining to configure how requests will be routed, either directly to the Internet, or to an upstream proxy server.

Network Load Balancing (Enterprise Edition)

You can use ISA Server to configure and manage the Network Load Balancing (NLB) functionality of Microsoft Windows Serverâ„¢ 2003 running on ISA Server arrays. When you configure NLB through ISA Server, NLB is integrated with ISA Server functionality. This provides important functionality that is not available in Windows NLB alone.

For more information about NLB, see the document Network Load Balancing in ISA Server Enterprise Edition at the Microsoft TechNet Web site. (

Enterprise networks (Enterprise Edition)

Before deploying arrays and array members in the enterprise, the enterprise administrator configures enterprise networks. An enterprise network is a network defined on the enterprise level that is global to all the arrays in the enterprise. An enterprise network is composed of IP ranges, and does not have any of the other properties that you would define for array networks.

An IP address can be included in only one enterprise network. IP addresses that are defined at the enterprise level, which are included in some enterprise network, are considered the address range for the enterprise. Typically, after you create an enterprise network, the network will be included in one or more array-level networks.

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