Configuring a Microsoft Exchange Server 2003 Infrastructure : Administrative and Routing Groups

Administrative Groups

Versions of Exchange Server prior to Exchange 2000 Server used the concept of sites, which defined the administrative and routing topology for an Exchange organization. Sites are familiar to administrators who have worked with Active Directory directory service, and the concept is very similar in defining the physical infrastructure of the organization. With Exchange Server 5.5, the administration model was tied directly to the routing and communication model, which was defined by the site. Beginning with Exchange 2000 Server and carried into Exchange Server 2003, the site concept is divided into administrative groups and routing groups. One limitation of the use of sites in previous versions of Exchange Server was that the administrative requirements of a large organization might not fit neatly within the site structure. As a result, the management of the administrative roles was more complicated, for example, in a situation where sites were defined geographically but administration was centralized. However, the centralized administration was delegated in a way that individual administrators were responsible for different sites. Exchange Server 5.5 sites are inflexible, so it is cumbersome in situations such as this to divide the administration in a way that goes against the site layout. With Exchange Server 2003, administrative groups are used to define the administrative topology of the Exchange organization. This is not tied to the physical topology, since in many organizations the administrative topology is different from the physical topology. It is possible for the administrative and routing group topology to correspond, but Exchange Server 2003 gives you the flexibility to separate them, if necessary.

Administrative groups can contain any of the following types of objects:

• Servers

• Policies

• Routing groups

• Public folder trees

You can think of an administrative group as a collection of the previous types of objects that have been organized into a container for simplified administration. You assign permissions to the administrative group rather than to the individual objects. This simplifies administration, for example, if you had 25 servers throughout Texas that all needed to have the same permissions, you could add them to a single administrative group rather than configuring the permissions individually on each server. This simplification is especially important when you consider ongoing administration of the organization after the initial configuration. If your company hires a new administrator and you need to add her to the list of administrators, it would be much simpler to do it once on an administrative group than having to configure each server.

Administrative Models

Administrative groups should be planned for prior to installing Exchange Server 2003, though they can be implemented before and after installation. The main reason it is important to plan your administrative groups prior to installing Exchange is because over the long term, it will be easier to support your organization and will require less administrative effort if you get it right the first time. In addition, there is less chance of users experiencing service disruptions because you need to reconfigure something.

Depending on your organization’s needs, there are different administrative models you can use: a centralized model, a decentralized model, or a mixed model that utilizes features of both. The centralized administrative model is most commonly used in small to mid-sized companies that have a limited number of IT personnel, but it can also be used in larger organizations that want to have their Exchange environment managed centrally by a few individuals. In a centralized model, there may be only one or two administrative groups used. Administrative groups do not have to follow the physical topology of an organization, so adding every server in a global organization to a single administrative group would have no effect on how the messaging infrastructure communicated.

The decentralized model is similar to how Exchange Server 5.5 sites were managed, where each site had its own administrative context (since message routing and administration were connected). Decentralized administration is most commonly used in larger organizations that have many branch locations operating independently of other locations, with their own local IT departments. In this type of model, you would have many administrative groups, perhaps one for each physical location.

The mixed model, as you would expect, uses a combination of centralized and decentralized administration. This model is most commonly used by larger organizations, where there is a need to centrally manage certain aspects of Exchange Server 2003, such as policies, while decentralizing administration of other aspects, such as the day-to-day Exchange server administration.

Once you have run ForestPrep and DomainPrep, you can gain access to the Exchange System Manager indirectly and create and modify administrative groups. Prior to the installation of Exchange (but after ForestPrep and DomainPrep are run), you can use the Active Directory Sites And Services console to modify the default administrative group. To create an administrative group after the installation of Exchange, use the Exchange System Manager utility, which is installed with Exchange Server 2003 and is located in the Microsoft Exchange program menu in the All Programs menu.

Routing Groups

Whereas administrative groups have no relationship to the physical network infrastructure, routing groups are directly related to the physical layout. You can think of routing groups as being much like Active Directory sites, which are used to group servers that share reliable, well-connected bandwidth. Routing groups come into play when you have multiple physical locations connected by slower wide area network (WAN) bandwidth, such as an Integrated Services Digital Network (ISDN) connection. Consider a scenario where you have two physical locations, Dallas and St. Louis, which have five servers running Exchange Server 2003 in each location. The two locations are physically connected by a 128K ISDN line. In this type of environment, you would create two routing groups, one for each location. This would map directly to the Active Directory site structure. Each routing group would contain its local servers, and a connector would be configured to connect the two routing groups. This could be either a routing group connector (the preferred way), an SMTP connector (for unreliable WAN connections), or an X.400 connector.

When you install the first Exchange Server 2003 server in an organization, a default routing group is created. You can rename this routing group to something more appropriate, and you can create additional routing groups using the Exchange System Manager utility. Creating routing groups is much like creating administrative groups, though a routing group is contained within an administrative group. As with administrative groups, by default, routing groups are not enabled. To enable routing groups, start Exchange System Manager, right-click on the organization name, click Properties, and select the check box to Display Routing Groups.

Subsequent Exchange servers are added to routing groups during the installation process, and if necessary, you can move servers between routing groups using Exchange System Manager. The only caveat is that in mixed mode, you cannot move servers between routing groups that belong to different administrative groups; you can only move servers between routing groups within the same administrative group. If you need to move a server to a routing group that is in a different administrative group, you must first move the server to the administrative group that contains the target routing group. Alternatively, you can move the entire routing group from one administrative group to another. This is a limitation of the default mixed mode operation, but once you convert to native mode, this limitation is lifted.

The other benefit that routing groups provide is a way of controlling message transfer. In this way, too, routing groups are very similar to Active Directory sites. With Active Directory, sites are used to define areas of well-connected bandwidth and areas of low bandwidth for the purpose of optimizing replication traffic. With routing groups, servers within a routing group are assumed to have high-speed, reliable bandwidth between them (such as on the same local area network [LAN]), and message transfer occurs immediately. Between routing groups, where bandwidth is assumed to be slow, a server in each group is designated as a bridgehead server, and traffic between routing groups is funneled through the bridgehead server in each group. This optimizes the flow of message traffic between routing groups and provides for a consistent, reliable flow of traffic.

1: Create Administrative Groups

You are the lead consultant of a team that is designing an Exchange Server 2003 infrastructure for Contoso, Ltd., a manufacturer of fine electric and acoustic guitars. The company has manufacturing plants in the United States, Mexico, Japan, and Germany, with world-wide headquarters in Dallas, Texas, and sales offices in Dallas, Boston, St. Louis, Los Angeles, Tokyo, Mexico City, and Berlin. You recommend a centralized administrative model for the United States and a decentralized model for the overseas locations. The proposal is accepted, and you begin to create the administrative groups after installing the first server running Exchange Server 2003 and creating the Contoso organization in Dallas.

2: Create Routing Groups

This exercise uses the same scenario as Exercise 1, but this time you will be creating routing groups. Since the overseas offices have only a single location apiece, you will need to create a single routing group in each administrative group. In the USA administrative group, you will want to rename the default routing group and create routing groups for each location (Dallas, Boston, St. Louis, and Los Angeles).