Configure a Windows DHCP failover relationship between two managed Windows DHCP servers by setting the necessary parameters that define such a relationship.
Windows DHCP servers must have already be under Address Manager control and must be in Read-Write mode. For details on adding a Windows DHCP Server to Address Manager, refer to Adding Managed Windows Servers.
- If deployment to a specific DHCP range/scope is not critical, change the
DHCP range in Address Manager then re-deploy DHCP to both
- If the deployment to a specific DHCP range/scope is critical, you
must first remove failover for the DHCP scope in conflict using the
Microsoft Management Console (MMC) from the server not managed by
Address Manager, then re-deploy DHCP to both managed servers from Address
Manager.Note: For this specific scenario only, do not attempt to manually remove the DHCP failover relationship that is in a non-normal state using the MMC from the Windows server managed by Address Manager, as this will also break the existing DHCP failover relationship in Address Manager.
To add a Windows DHCP failover relationship:
- Select the My IPAM tab. From the configuration drop-down menu, select a configuration.
- Select the Servers tab. Tabs remember the page you last worked on, so select the Servers tab again to ensure you are working with the Configuration information page.
- Expand Windows DHCP Failover Relationships, then click New and select Windows DHCP Relationship. The Add Windows DHCP Failover Relationship page opens.
In the Name field, enter a unique name for the Windows
DHCP Failover relationship.
Note: The name of the DHCP Failover Relationship must be unique per Windows server. Address Manager will not allow the addition of relationship names that break this uniqueness rule. For example: Relationship 1 (R1) has been configured with Server 1 (S1) and Server 2 (S2); Relationship 1 is also configured with Server 3 (S3) and Server 4 (S4). You cannot configure Relationship 1 with Server 2 and Server 3.
- R1 (S1, S2) and R1 (S3,S4) can co-exist but R1 (S1, S2) and R1 (S2, S3) cannot.
To add a Primary Server, click
Select. The Select Server Interface pop-up
Only managed R/W Windows Servers will appear in the drop-down menu.
- Under Servers, click the server you wish to use as the Primary.
- Under Server Interfaces, select the primary server interface and click Add. If necessary, click Up to return to the list of servers. The selected server and its IP address appear on the Add Windows DHCP Failover Relationship page. If necessary, click Remove to delete the server and start again.
To add a Secondary Server, click
Select. The Select Server Interface pop-up
- Under Servers, click the server you wish to use as the Secondary.
- Under Server Interfaces, select the secondary server interface and click Add. If necessary, click Up to return to the list of servers. The selected server and its IP address appear on the Add Windows DHCP Failover Relationship page. If necessary, click Remove to delete the server and start again.
- In the Maximum Client Lead Time field, enter a unit of time then select either Seconds, Minutes, Hours or Days from drop-down menu (by default, 1 hour). The MCLT is the maximum time that one server can extend a lease for a DHCP client beyond the time known by the partner server.
From the Failover Mode drop-down menu select either
Load Balance or Hot Standby (by default, Load Balance).
Available options will change depending on your selection:
Note: BlueCat recommends Load Balance for most scenarios as it is ideal for single-site deployments where the pair of Windows servers in a DHCP failover relationship are located within the same networks being served by them. Hot Standby is an active/passive failover mode where only one server actively serves DHCP leases and the other remains passive unless the active goes down.
- Load Balance Percentage—enter the load balance percentage for the Primary Server in the text field (by default, 50:50). Address Manager will automatically calculate the percentage for the Secondary Server.
- Hot Standby Percentage—enter the Hot Standby percentage for the Primary Server in the text field (by default, 95:5). Address Manager will automatically calculate the percentage for the Secondary Server.
- OPTIONAL: BlueCat strongly recommends that customers do not use Automated State Switchover and the option is deselected by default. However, if modifying the option is necessary, select the State Switchover Interval check box, enter a time interval in the text field, then select either Seconds, Minutes, Hours, or Days from the drop-down menu (by default, 1 hour).
OPTIONAL: By default, Shared Secret is
deselected. However, if you want to enable authentication between the two
Windows Servers, select the check box and enter the shared secret in the text
field. The text will remain hidden like a password.
Note: The default Shared Secret is blank, meaning that no authentication is enabled.
- Under Change Control, add comments to describe your changes. By default, this step is optional but might be set as a requirement.
- Click Add or click Add Next to create additional Windows DHCP failover relationships.