For private, external and public networks, Abiquo can manage their corresponding VLANs with an ISC DHCP server. Abiquo recommends one DHCP server per physical datacenter, registered in remote services. For these networks you can use a Remote services DHCP server supplied with Abiquo or other compatible server. If you have many virtual networks, you might need a separate relay server to manage VLANs for the DHCP server. Add the DHCP service to Abiquo when creating or editing a datacenter
For unmanaged networks, you do not need to configure a DHCP server and you must provide the network addresses to the virtual machines outside of Abiquo.
How Abiquo uses DHCP
The connections in DHCP are as follows:
- When you deploy a virtual machine, Abiquo (Remotes Services) supplies the network settings for the new VM to the DHCP Server.
- When the new virtual machine powers on, it broadcasts a DHCP request for network configuration.
- The hypervisor passes the DHCP request through a VLAN to the DHCP server.
- The DHCP server broadcasts a lease with the network configuration for the virtual machine over the same VLAN
DHCP Configurations
When configuring DHCP for a datacenter using the remote services, the possible DHCP configurations are:
- DHCP Server only for < 200 VLANs
- DHCP Server with DHCP Relay for < 1000 VLANs
- DHCP Server with muliptle DHCP Relays for > 1000 VLANs.
Abiquo recommends that you use a separate machine for VLAN support, not the DHCP Server included with the Remote Services. Remember to enter the DHCP Server address in the Remote Services for your physical datacenter in the Abiquo GUI. If you are using a DHCP Relay Server, do not configure support for VLANs on the DHCP Server. If you need to add more VLANs to this configuration, you can add more relay servers at a later date.
DHCP Server
The DHCP Server listens to all the VLANs. Abiquo recommends that you use a separate DHCP Server (not the Remote Services DHCP Service) in this configuration.
DHCP Server with DHCP Relay
The DHCP relay server listens to all the VLANs and forwards the DHCP requests to the DHCP Server. In this configuration you can use the DHCP server on the Remote Services server.
DHCP Server with multiple DHCP Relays
Multiple DHCP relay servers allow you to create large networks in a hierarchical forwarding structure.
DHCP Installation Guide
The DHCP Relay Server (or DHCP Server if no relays are used) must be able to listen to VLANs. So it must be a separate physical machine or a virtual machine on a hypervisor with VLAN support, such as VMware ESXi (see How to configure an ESXi host to support VLAN tagging) or RedHat KVM.
You can install a DHCP Relay server with the Abiquo OVA install - see Automatically Configuring One DHCP Relay Server.
These configurations are designed for multiple VLAN networks, which by definition have separate VLAN tags and isolate DHCP broadcasts. The server managing VLANs (DHCP Relay or DHCP Server) must have one VNIC or NIC with an IP address for each VLAN that will identify the VLAN to the DHCP Server. The DHCP Server and VM communicate through broadcasts, which are also relayed, until the IP address of the VM is set, so there is no specific requirement for the IP address of the VNIC or NIC. However, it is recommended that the IP address range is not part of any other networks. For example, you could use the upper range of the management network. If you have complex requirements, you may need to adapt these configurations.
If you need to use multiple relay servers, see Manually Configuring Multiple DHCP Relay Servers