# Creating HVM Overlay Network

## About this task

An HVM Overlay Network uses VXLAN tunneling to provide isolation for east-west VM traffic across hosts. It enables tenant network segmentation without requiring physical VLAN configuration on upstream switches. The system deploys a dedicated OVS bridge for each overlay network on every host and configures a VXLAN tunnel endpoint on a designated host interface.

NOTE

The HVM Overlay Network does not use the same OVS Bridge Domain virtual switch as Standard Networks. Instead, the system creates a dedicated OVS bridge for each Overlay Network on every host, ensuring complete isolation from other networks.

## Procedure

1. Navigate to Infrastructure > Network > Networks
2. Select + Add > HVM Overlay Network
3. Enter the following details in the Create Network:

   - Group: Select the group to which the data network belongs from the drop down menu.
   - Network Service: Select the network service to which the data network belongs from the drop down menu.
   - Name: Enter the name of the network.
   - Display Name: Enter a user-friendly name. The system displays this name in the UI.
   - Labels: Enter comma-separated labels. Use labels to organize and filter networks.
   - Description: Enter a description to document the purpose or usage of the network.
   - Enable IPv4: Enable this option to configure IPv4 for the network.
   - CIDR: Specify the IP subnet for the overlay network (for example, 10.10.10.0/24). The system does not allow modification of this value after creation.
   - Resource Pool: Select the HVM cluster where you want to create the network.
   - Overlay Net Interface: Select the host network interface that the system uses as the VXLAN tunnel endpoint (for example, `bond0`). Ensure that this interface has a reachable IP address and exists on every host in the cluster.
   - Overlay Port: Specify the UDP port used for VXLAN encapsulation. The system uses 4789 as the default.
   - Overlay ID: Provide a unique VXLAN Network Identifier (VNI) in the range 1–16,777,215. The system uses this ID to identify and isolate the overlay network.
   - Active: Select this checkbox to activate the network immediately upon creation.
   - DHCP Server: Select this checkbox to enable the internal Dynamic Host Configuration Protocol (DHCP) server for automatic IP assignment.
   - Allow IP Override: Select this checkbox to let workloads override their assigned IP addresses.
   - Network Pool: Select an IP address pool from the drop-down menu to allocate blocks for this network.
   - Domain: Select the network search domain from the drop-down menu to resolve hostnames.
   - IPv6 Options: Expand this section to configure Internet Protocol version 6 (IPv6) network settings.

     - Enable IPv6: Select this checkbox to activate IPv6 routing and addressing on the network.
     - CIDR : Enter the IPv6 network address and routing prefix block in CIDR notation.
     - DHCP Server: Select this checkbox to enable automatic IPv6 addressing via the internal DHCPv6 server
     - Network Pool: Select an IPv6 address pool from the drop-down menu to allocate blocks for this network.
   - Advanced Options: Expand this section to configure advanced routing and network proxy parameters.

     - Search Domains: Enter a space-separated or comma-separated list of DNS search domains to resolve short hostnames.
     - Proxy: Select a designated proxy server profile from the drop-down menu to route external network traffic.
     - Bypass Proxy For Appliance URL: Select this checkbox to route internal management appliance traffic directly instead of using the proxy server.
     - No Proxy: Enter a comma-separated list of IP addresses, subnets, or domains to bypass proxy server routing.
   - Guest Console Options: Expand this section to configure remote access properties for guest workloads.

     - VDI Gateway: Select the Virtual Desktop Infrastructure (VDI) gateway from the drop-down menu to handle remote console traffic.
     - SSH Jump Host: Enter the endpoint address of the Secure Shell (SSH) bastion or jump host to secure external administrative access.
     - SSH Jump Port: Enter the port number for the SSH jump host.
     - SSH User: Enter the credential username for the SSH jump host.
     - SSH Password: Enter the credential password for the SSH jump host.
     - SSH Keypair: Select an SSH key pair from the drop-down menu.
   - Group Access: Expand this section to manage access for specific groups.

     - Access Select this checkbox to grant network access to the group.
     - Default Select this checkbox to make this network the group default.
4. Click Save Changes

## Results

The system creates a dedicated OVS bridge on each host, configures a VXLAN tunnel endpoint on the selected interface, and creates a libvirt network definition that maps to the bridge.
