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Configure DHCP for Azure VMware Solution

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Applications and workloads running in a private cloud environment require name resolution and DHCP services for lookup and IP address assignments. A proper DHCP and DNS infrastructure are required to provide these services. You can configure a virtual machine to provide these services in your private cloud environment.

Use the DHCP service built-in to NSX-T Data Center or use a local DHCP server in the private cloud instead of routing broadcast DHCP traffic over the WAN back to on-premises.

Important

If you advertise a default route to the Azure VMware Solution, then you must allow the DNS forwarder to reach the configured DNS servers and they must support public name resolution.

In this how-to article, you'll use NSX-T Manager to configure DHCP for Azure VMware Solution in one of the following ways:

Tip

If you want to configure DHCP using a simplified view of NSX-T Data Center operations, see Configure DHCP for Azure VMware Solution.

Important

For clouds created on or after July 1, 2021, the simplified view of NSX-T Data Center operations must be used to configure DHCP on the default Tier-1 Gateway in your environment.

DHCP does not work for virtual machines (VMs) on the VMware HCX L2 stretch network when the DHCP server is in the on-premises datacenter. NSX-T Data Center, by default, blocks all DHCP requests from traversing the L2 stretch. For the solution, see the Configure DHCP on L2 stretched VMware HCX networks procedure.

Use the Azure portal to create a DHCP server or relay

You can create a DHCP server or relay directly from Azure VMware Solution in the Azure portal. The DHCP server or relay connects to the Tier-1 gateway created when you deployed Azure VMware Solution. All the segments where you gave DHCP ranges will be part of this DHCP. After you've created a DHCP server or DHCP relay, you must define a subnet or range on segment level to consume it.

  1. In your Azure VMware Solution private cloud, under Workload Networking, select DHCP > Add.

  2. Select either DHCP Server or DHCP Relay and then provide a name for the server or relay and three IP addresses.

    Note

    For DHCP relay, you only require one IP address for a successful configuration.

    Screenshot showing how to add a DHCP server or DHCP relay in Azure VMware Solutions.

  3. Complete the DHCP configuration by providing DHCP ranges on the logical segments and then select OK.

Use NSX-T Data Center to host your DHCP server

If you want to use NSX-T Data Center to host your DHCP server, you'll create a DHCP server and a relay service. Then you'll add a network segment and specify the DHCP IP address range.

Create a DHCP server

  1. In NSX-T Manager, select Networking > DHCP, and then select Add DHCP Profile.

  2. Select Add DHCP Profile, enter a name, and select Save. NOTE: An IP address is not required if none is entered NSX-T Manager will set one.

    Screenshot showing how to add a DHCP Profile in NSX-T Manager.

  3. Under Networking > Tier-1 Gateways, select the gateway where the segments are connected that DHCP is required. Edit the Tier-1 Gateway by clicking on the three ellipses and choose Edit.

  4. Select Set DHCP Configuration, select DHCP Server and then select the DHCP Server Profile created earlier. Click Save, then Close Editing.

    Screenshot showing how to edit the NSX-T Data Center Tier-1 Gateway for using a DHCP server.

  5. Navigate to Networking > Segments and find the segment where DHCP is required. Click on Edit then Set DHCP Config.

  6. Select Gateway DHCP Server for DHCP Type, add a DHCP range, and click Apply.

    Screenshot showing how to add a subnet to the NSX-T Data Center Tier-1 Gateway for using a DHCP server.

Add a network segment

  1. In NSX-T Manager, select Networking > Segments, and then select Add Segment.

    Screenshot showing how to add a new segment in NSX-T Manager.

  2. Enter a name for the segment.

  3. Select the Tier-1 Gateway (TNTxx-T1) as the Connected Gateway and leave the Type as Flexible.

  4. Select the pre-configured overlay Transport Zone (TNTxx-OVERLAY-TZ) and then select Set Subnets.

    Screenshot showing the Segments details for adding a new NSX-T network segment.

  5. Enter the gateway IP address and then select Add.

    Important

    The IP address needs to be on a non-overlapping RFC1918 address block, which ensures connection to the VMs on the new segment.

    Screenshot showing the IP address of the gateway for the new segment.

  6. Select Apply and then Save.

  7. Select No to decline the option to continue configuring the segment.

Specify the DHCP IP address range

When you create a relay to a DHCP server, you'll also specify the DHCP IP address range.

Note

The IP address range shouldn't overlap with the IP range used in other virtual networks in your subscription and on-premises networks.

  1. In NSX-T Manager, select Networking > Segments.

  2. Select the vertical ellipsis on the segment name and select Edit.

  3. Select Set Subnets to specify the DHCP IP address for the subnet.

    Screenshot showing how to set the subnets to specify the DHCP IP address for using a DHCP server.

  4. Modify the gateway IP address if needed, and enter the DHCP range IP.

    Screenshot showing the gateway IP address and DHCP ranges for using a DHCP server.

  5. Select Apply, and then Save. The segment is assigned a DHCP server pool.

    Screenshot showing that the DHCP server pool assigned to segment for using a DHCP server.

Use a third-party external DHCP server

If you want to use a third-party external DHCP server, you'll create a DHCP relay service in NSX-T Manager. You'll also specify the DHCP IP address range.

Important

For clouds created on or after July 1, 2021, the simplified view of NSX-T Data Center operations must be used to configure DHCP on the default Tier-1 Gateway in your environment.

Create DHCP relay service

Use a DHCP relay for any non-NSX-based DHCP service. For example, a VM running DHCP in Azure VMware Solution, Azure IaaS, or on-premises.

  1. In NSX-T Manager, select Networking > DHCP, and then select Add Server.

  2. Select DHCP Relay for the Server Type, provide the server name and IP address, and select Save.

    Screenshot showing how to create a DHCP relay service in NSX-T Manager.

  3. Select Tier 1 Gateways, select the vertical ellipsis on the Tier-1 gateway, and then select Edit.

    Screenshot showing how to edit the NSX-T Data Center Tier-1 Gateway.

  4. Select No IP Allocation Set to define the IP address allocation.

    Screenshot showing how to add a subnet to the NSX-T Data Center Tier-1 Gateway.

  5. For Type, select DHCP Server.

  6. For the DHCP Server, select DHCP Relay, and then select Save.

  7. Select Save again and then select Close Editing.

Specify the DHCP IP address range

When you create a relay to a DHCP server, you'll also specify the DHCP IP address range.

Note

The IP address range shouldn't overlap with the IP range used in other virtual networks in your subscription and on-premises networks.

  1. In NSX-T Manager, select Networking > Segments.

  2. Select the vertical ellipsis on the segment name and select Edit.

  3. Select Set Subnets to specify the DHCP IP address for the subnet.

    Screenshot showing how to set the subnets to specify the DHCP IP address.

  4. Modify the gateway IP address if needed, and enter the DHCP range IP.

    Screenshot showing the gateway IP address and DHCP ranges.

  5. Select Apply, and then Save. The segment is assigned a DHCP server pool.

    Screenshot showing that the DHCP server pool assigned to segment.

Next steps

If you want to send DHCP requests from your Azure VMware Solution VMs to a non-NSX-T DHCP server, see the Configure DHCP on L2 stretched VMware HCX networks procedure.