Documentation forIP Address Manager

Set up and monitor Windows DHCP server failover

IPAM makes configuring failover across multiple scopes simple, using a single screen to configure information for all your scopes, whereas in Windows Server you can only configure failover a single scope at a time.

What is DHCP failover?

DHCP failover is a feature introduced with Windows Server® 2012 enabling two Microsoft DHCP servers to share service availability information with each other, thus providing DHCP high availability for load balancing or redundancy purposes. IP address leases and settings in one or more DHCP scopes are replicated from the primary DHCP server to a failover partner server.

There are two failover modes that can be used:

  • Load balance mode allocates DHCP client leases across two servers.

    In this mode, a pair of servers are both active, serving IP addresses and options on a scope or subnet, and requests are shared according to the load balancing ratio set up for the two servers. The default is 50:50, but can be set from 0:100 to 100:0 as required.

    With load balancing, if one server becomes unavailable, the other will receive 100% of requests until it is restored.

  • Hot standby mode provides redundancy for DHCP services

    In this mode there is an active server, which is responsible for leasing IP addresses and configuration information to all clients in a scope or subnet, and a standby server, which will only issue leases to DHCP clients if the active server is unavailable.

You can set up multiple relationships, of both modes, for a server.

For complete information about DHCP failover, see the Microsoft TechNet guide, Understand and Deploy DHCP Failover (© 2016 Microsoft, available at https://microsoft.com, obtained on July 8, 2021).

Failover is not supported for Cisco, ISC or Infoblox DHCP environments.

View DHCP failover details in IPAM

  1. Open the Orion Web Console and navigate to My Dashboards > IP Addresses > DHCP & DNS Management.

    Select the DHCP Server tab.

    If using the legacy view, select the DHCP tab.

  2. Select the required server, and move the cursor over the Failover column for the required Server.

    IPAM consolidates cluster details into a single pop-up, whereas Windows Server only displays failover details one scope at a time.

Create or Edit DHCP failover details in IPAM

To configure DHCP failover from IPAM, both DHCP servers must be managed by IPAM.

  1. Open the Orion Web Console and choose My Dashboards > IP Addresses > DHCP & DNS Management.

  2. Select the DHCP Server tab.

    If using the legacy view, select the DHCP tab.

  3. Select the required server, and click Edit.

    The Edit DHCP Server box opens.

  4. Select the Failover Editor section.

    Enter the following information for the failover relationship:

    Field Description
    Relationship name Enter a name for this failover relationship. This must be unique for this server.
    Mode Select Load balance or Hot Standby.
    Partner Server Select the partner server from this drop-down.
    Selected Scopes You can specify the scopes associated with this failover relationship.
    Load balance local server (Load balance only) Enter the percentage of DHCP client requests to be serviced by the local DHCP server. This can be between 0% and 100%.
    Load balance partner server (Load balance only) Enter the percentage of DHCP client requests to be serviced by the partner DHCP server. This can be between 0% and 100%, but the local and partner percentages must add up to 100%.
    State switch interval (Load balance only) Optional. The interval in minutes before the local server transitions its failover partner to a partner down state when a loss of communication occurs. If not specified, the default is 60 minutes.
    Addresses reserved for standby server (Hot Standby only)

    Specify the percentage of the address range of the scope to be reserved for the hot standby server. The default is 5%.

    These addresses are used to service new clients if the primary server goes down, during the time interval (the State switch interval) before the standby server assumes control over the entire IP address range of a scope.

    Shared secret Optional.
  5. If you want to add a further relationship for this server, click Add new relationship, and complete the fields as above.
  6. Click Save to save your changes.