How to Set an Exchange Cost on an Active Directory IP Site Link
Applies to: Exchange Server 2007 SP3, Exchange Server 2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2007-03-19
This topic explains how to use the Exchange Management Shell to set an Exchange cost on an Active Directory directory service IP site link in Microsoft Exchange Server 2007. By default, Microsoft Exchange uses the cost assigned to an IP site link for Active Directory replication purposes to compute a routing topology. The existing IP site link costs should work well for Exchange 2007 message routing because Active Directory IP site link costs are based on relative network speed compared to all network connections in the WAN and are designed to produce a reliable and efficient replication topology,. However, if after you document the existing Active Directory site and IP site link topology, you determine that the Active Directory site link costs and network traffic flow patterns are not optimal for Exchange 2007, you can make adjustments to the costs that are used by Exchange routing. An Exchange administrator cannot and should not use Active Directory tools to modify the cost that is assigned to the IP site link. Instead, use the Set-ADSiteLink cmdlet in the Exchange Management Shell to assign an Exchange-specific cost to the IP site link.
When an Exchange-specific cost is assigned to an IP site link, the Exchange cost effectively overrides the Active Directory cost for message routing only, and routing only considers the Exchange cost when it evaluates the least cost routing path.
To force relay of all message delivery through a hub site, you may find adjusting IP site link costs useful.
Determine the name of the Active Directory IP site link for which you want to set an Exchange cost. You can examine the contents of the Routing Table logs and view the data in the ADTopologyPath ID section to view details about the calculated least cost routing path between two Active Directory sites.
To perform this procedure, 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 2007, see Permission Considerations.
Run the following command to set an Exchange cost on an Active Directory IP site link:
Set-AdSiteLink -Identity IPSITELINKAB -ExchangeCost 10
Run the following command to clear the Exchange cost previously set on an Active Directory IP site link and revert to using the Active Directory assigned cost:
Set-AdSiteLink -Identity IPSITELINKAB -ExchangeCost $null
For detailed syntax and parameter information, see Set-AdSiteLink.