Exchange 2013 Free Busy Information – Cross Forest Topologies
Availability service is used to get the free busy information of user calendar. This becomes more important when we want to publish the free busy information of user calendar when it located in another forest.
This can be achieved by two ways
1. Creating mutual two-way trust between active directory forest
2. Without creating two-way trust between active directory forest
When we create trust between two forest the availablity service can be configured on user basis level and we have control on user availability service.
In some cases we will not able to create two way trust between forest due to business restriction or policy. In this case the availablity service can be configured on organization level and we don’t have much control on user’s free/busy information
On both the case the GAL Sync between the two forest should be configured. If not users will not able to other forest user contact information. Gal sync can be done using various tool – IFM, FIM, third party ( I will try to explain them in my next post)
Note: Target Forest means where free/busy information will displayed.
Source Forest means the location of user object
When you want to publish the free/busy information having trust between forest run the below powershell command in both the source forest and target forest
Get-ClientAccessServer | Add-ADPermission -Accessrights Extendedright -Extendedrights “ms-Exch-EPI-Token-Serialization” -User “<Remote Forest Domain>\Client Access
Add-AvailabilityAddressSpace -Forestname mail.com -AccessMethod PerUserFB -UseServiceAccount:$true
When you want to publish the free/busy information without having trust between forest run the below powershell command
Command needs to run in target forest
Set-AvailabilityConfig -OrgWideAccount “mail.com\User”
Command needs to run in source forest
$Account = get-credential
Please Type “DomainName\Username” and Password
Add-AvailabilityAddressspace -Forestname mail.com -Accessmethod OrgWideFB -Credential:$Account