Dhcp Azure Network Configuration and Management

DHCP Azure Network Configuration and Management is a crucial aspect of setting up and managing your Azure network. DHCP (Dynamic Host Configuration Protocol) is a protocol that automatically assigns IP addresses to devices on a network.

Azure provides a built-in DHCP service that can be used to manage IP address assignments. This service can be configured to assign IP addresses from a specific IP address range.

You can safely install a DHCP service in your Azure VM, but it won't work for providing IP configuration for your VMs.

Azure Network is based on Hyper-V network virtualization, VXLAN, which encapsulates network packets and sends them directly to their destination.

A DHCP server in the same subnet or VNET can't answer to other VMs on the same subnet or VNET because broadcast messages aren't transmitted in Azure Virtual Network.

Using a DHCP service on a VM to serve other VMs on the same network is ineffective, as VMs will always get the VNET configuration and no discovery can be made to the DHCP server.

However, there's a scenario where having a DHCP server in Azure makes sense: when you use a Hybrid Network with Express Route, Site-to-Site VPN, or SD-Wan.

In this case, you can use a DHCP relay agent to retransmit broadcast messages as unicast messages, which are allowed in Azure networking.

A DHCP relay agent is a service that listens to broadcast messages on its local network and retransmits the request to a DHCP server using a unicast message.

Azure has recently removed the rate limit on unicast packets to UDP 67, allowing you to deploy a DHCP server without restriction.

You should use DHCP client on the interfaces of your Palo Alto Network (PAN) devices, as it eases automated deployments and prevents misconfiguration.

Static IP assignment can lead to issues if it doesn't match the assigned IP on the Azure side, causing traffic to not flow.

When assigning multiple IPs to an interface for NAT purposes, you should specify them directly as objects or in security or NAT policy.

You can add additional IPs to the firewall interface from within the Azure portal, but you'll need to switch to static on the firewall and manually add the first and additional IPs that you want to service.

However, on the load balancer, you can enable floating IP on the rule, and the requested IP will come through to the firewall, allowing you to stay with DHCP on the firewall.

You can bootstrap the network interface and VR configuration on Panorama, and then let it push down the policy and other information when the VM registers itself.

Configuring DHCP in Azure can be a bit tricky, but it's essential for managing IP configurations in your virtual network. You can safely install a DHCP service in your Azure VM, but it won't work for providing IP configurations for your VMs.

To understand why, remember that Azure Network is based on Hyper-V network virtualization, VXLAN. This model intercepts broadcast messages, including DHCP discovery messages, and handles configuration using the subnet configuration. A DHCP server in the same subnet or VNET can't answer to other VMs on the same subnet or VNET because broadcast messages aren't transmitted in Azure Virtual Network.

You can create a DHCP server or relay directly from Azure VMware Solution in the Azure portal. To do this, select DHCP > Add under Workload Networking, then provide a name for the server or relay and three IP addresses. For DHCP relay, you only need one IP address.

Here's a step-by-step guide to creating a DHCP server or relay:

Creating a DHCP server or relay in the Azure portal is a straightforward process. You can do this directly from Azure VMware Solution in the portal.

To start, go to your Azure VMware Solution private cloud, under Workload Networking, select DHCP > Add. From there, you can choose to create either a DHCP server or a relay.

A 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 are part of this DHCP.

To create a DHCP server or relay, you'll need to provide a name for the server or relay and three IP addresses. For a DHCP relay, you only need one IP address for a successful configuration.

Here's a step-by-step guide to creating a DHCP server or relay:

Once you've created a DHCP server or relay, you'll need to define a subnet or range on segment level to consume it.

To configure DHCP, you need to specify the DHCP IP address range. This range should not overlap with the IP range used in other virtual networks in your subscription and on-premises networks.

The DHCP IP address range is set in the NSX Manager, specifically in the Segments section. You can access this by navigating to Networking > Segments.

To modify the DHCP IP address range, select the vertical ellipsis on the segment name and choose Edit. From there, select Set Subnets to specify the DHCP IP address for the subnet.

The gateway IP address can be modified if needed, and the DHCP range IP must be entered. After making these changes, select Apply and then Save. This will assign a DHCP server pool to the segment.