How to Configure the Availability Service for Cross-Forest Topologies

Exchange 2007
How to Configure the Availability Service for Cross-Forest Topologies
Applies to: Exchange Server 2007, Exchange Server 2007 SP1 Topic Last Modified: 2007-03-28
This topic explains how to use the Exchange Management Shell to configure the Availability service for cross-forest topologies. The Availability service improves information workers' free/busy data by providing secure, consistent, and up-to-date free/busy information to computers that are running Microsoft Office Outlook 2007. By default, this service is installed with Microsoft Exchange Server 2007. In cross-forest topologies where all connecting client computers are running Outlook 2007, the Availability service is the only method of retrieving free/busy data.
Note:
You cannot use the Exchange Management Console to configure the Availability service for cross-forest topologies.
You can use the Availability service in cross-forest topologies across trusted or untrusted forests. The type of free/busy information is determined by whether the cross-forest free/busy data is configured as a per-user or an organization-wide service. Per-user free/busy information is possible only in a trusted cross-forest topology and makes it possible for the Availability service to make cross-forest requests on behalf of a particular user. This also allows a user in a remote forest to grant detailed free/busy information to a cross-forest user.
However, with organization-wide free/busy data, the Availability service can make cross-forest requests only on behalf of a particular organization. With organization-wide free/busy data, a user's default free/busy information is returned, and it is not possible to control the level of free/busy information that is returned to users in the other forest.
Configuring Windows for Cross-Forest Topologies

To configure Microsoft Windows for a cross-forest topology, you must install and configure GAL Synchronization (GALSync). For complete information about how to install and configure the GALSync feature in Microsoft Identity Integration Server (MIIS) 2003, see the following resources:
Microsoft Identity Integration Server 2003 Scenarios
Microsoft Identity Integration Server 2003
If you are running Office Outlook 2003 or earlier, you must use the Microsoft Exchange Inter-Organization Replication tool to synchronize free/busy data across multiple forests. For more information about the Microsoft Exchange Inter-Organization Replication tool, see Microsoft Exchange Server Inter-Organization Replication.
Before You Begin

To run the Get-ClientAccessServer cmdlet, the account you use must be delegated the following:
Exchange View-Only Administrator role
To run the Add-ADPermission cmdlet, the account you use must be delegated the following:
Exchange Organization Administrator role
To run the Add-AvailabilityAddressSpace cmdlet, the account you use must be delegated the following:
Exchange Organization Administrator role
To run the Set-AvailabilityConfig cmdlet, the account you use must be delegated the following:
Exchange Organization Administrator role
For more information about permissions, delegating roles, and the rights that are required to administer Exchange Server 2007, see Permission Considerations.
Procedure

To use the Exchange Management Shell to configure per-user free/busy data in a trusted cross-forest topology

On a Client Access server in the target forest, run the following commands to configure the Availability service for per-user free/busy data:
Copy CodeGet-ClientAccessServer Add-ADPermission -Accessrights Extendedright -Extendedrights "ms-Exch-
EPI-Token-Serialization" -User "\Client Access servers"
On the local Client Access server in the source forest, run the following command to define the access method and associated credentials:
Copy CodeAdd-AvailabilityAddressSpace -Forestname ContosoForest.com -AccessMethod PerUserFB -UseServiceAccount:$true
Note:
To configure bidirectional cross-forest availability, repeat these steps in the target forest.
For detailed syntax and parameter information, see the following cmdlet reference topics:
Get-ClientAccessServer
Add-ADPermission
Add-AvailabilityAddressSpace
Set-AvailabilityConfig
To use the Exchange Management Shell to configure organization-wide free/busy data in an untrusted cross-forest topology

On a Client Access server in the target forest, run the following command to set the organization-wide account on the availability configuration object to configure the access level for free/busy information:
Copy CodeSet-AvailabilityConfig -OrgWideAccount "Contoso.com\User"
Run the following commands to add the Availability address space configuration object for the source forest:
Copy Code$a = get-credential (Enter the credentials for organization-wide user in Contoso.com domain)
Add-AvailabilityAddressspace -Forestname Contoso.com -Accessmethod OrgWideFB -Credential:$a
If you choose to configure cross-forest availability with trust, and choose to use a service account (instead of specifying organization-wide or per-user credentials), you need to run the following command in the target forest to give Client Access servers in the source forest permission to serialize original user context.
To use the Exchange Management Shell to configure trusted cross-forest availability with a service account

Run the following command to configure trusted cross-forest availability with a service account:
Copy CodeGet-ClientAccessServer Add-ADPermission -Accessrights Extendedright -Extendedright "ms-Exch-EPI-Token-Serialization" -User "\Exchange servers"
Exchange 2007 and Exchange 2003 Cross-Forest Availability

For Outlook 2007 and Exchange 2007 users to view the free/busy information of Exchange Server 2003 users in another forest, you must configure the Availability service by using the Add-AvailabilityAddressSpace cmdlet. You will only need to run this command once on any server in the Exchange 2007 forest.
To use the Exchange Management Shell to configure Exchange 2007 and Exchange 2003 cross-forest availability

Run the following command to set public folder free/busy availability:
Copy CodeAdd-AvailabilityAddressSpace -ForestName Contoso.com -AccessMethod PublicFolder
Note:
To replicate free/busy information and public folder content between Exchange organizations you must use the Microsoft Exchange Inter-Organization Replication tool. For more information about the Microsoft Exchange Inter-Organization Replication tool, see Microsoft Exchange Server Inter-Organization Replication.