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Introduction

Each virtual machine network has a corresponding VLAN (or VXLAN with NSX). 

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For Abiquo private, external and public networks, Abiquo uses  the platform can manage the corresponding VLANs with an ISC DHCP server to manage VLANs (or VXLANs). 

Abiquo recommends one DHCP server per physical datacenter registered in remote services. Additional DHCP servers may be incorporated in network virtualization solutions. The types of DHCP server configuration are as follows: 

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. When you configure the datacenter, add the DHCP service to Abiquo. 

• 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
  
• DHCP server incorporated in an integrated network virtualization system
  
  • In an Abiquo datacenter, create a logical device that will enable Abiquo to connect via the API of the network virtualization system to its DHCP server. See Create SDN Devices.
  • If the network virtualization system DHCP server is not available, Abiquo will fall back to the datacenter remote services DHCP server
    

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• . 

• For unmanaged networks only, you do not need to configure a DHCP server

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• and you must provide the network addresses to the

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• VMs outside of Abiquo.

To display the version of DHCP used by Abiquo, run the following command on the Abiquo remote services :

# /usr/sbin/dhcpd --version
isc-dhcpd-4.1.1-P1

Abiquo uses the DHCP server to: 

• Manage the VLANs (or VXLANS), serving IP addresses to virtual machines
• Serve static routes to virtual machines using the DHCP option
• Serve information from the Chef integration using the vendor encapsulated options
  
  • The Chef integration is not available with NSX

How Abiquo Uses DHCP

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How Abiquo uses DHCP

Abiquo standard VLAN management has the following features:

• Virtual networks as separate VLANs

• The Cloud Administrator defines VLAN tag pools in Abiquo when creating the racks

• External and public networks are created in the infrastructure and defined in Abiquo later

• Private networks will be defined by Abiquo from the VLAN tag pools of the racks

The connections in DHCP are as follows:

1. When you deploy a

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1. VM, Abiquo (Remotes Services) supplies the network settings for the new VM to the DHCP Server.

2. When the new

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1. VM powers on, it broadcasts a DHCP request for network configuration.

2. The hypervisor passes the DHCP request through a VLAN to the DHCP server.

3. The DHCP server broadcasts a lease with the network configuration for the

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1. VM over the same VLAN

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DHCP Configurations

When configuring DHCP for a datacenter using the remote services, the possible DHCP configurations are:

The first configuration (DHCP Server only) is recommended only for test environments or small environments that will not be scaled up. The configuration with the DHCP relay server is recommended by Abiquo because it easy to set up and troubleshoot and it also scales well. 

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.

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DHCP Server with DHCP Relay

The DHCP relay server listens to the DHCP infrastructure, there are several choices depending on the number of VLANs in the environment.

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DHCP server only, for < 200 VLANs.

The Server listens to all VLANs. We recommend using a dedicated DHCP Server for this configuration.

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DHCP server with DHCP relay, for < 1000 VLANs.

The relay server listens on all the VLANs and forwards the DHCP requests to the Server.
In this configuration you can use the DHCP server on the Remote Services server. Do not configure support for VLANs on the DHCP Server.
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DHCP

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server with multiple DHCP

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relays, for > 1000 VLANs

Multiple DHCP relay servers allow you to create large networks in a hierarchical forwarding structure.

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DHCP

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configuration notes

The server managing a VLAN (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 specially configured virtual machine.
If you wish to use a virtual machine, follow one of these configuration guides to prepare the virtual machine:

• VMware ESXi (see How to configure an ESXi host to support VLAN tagging); or
• Red Hat KVM

Then continue with the appropriate install section for your configuration

Install DHCP Server

1. Install CentOS

2. Install a separate DHCPD server

   Code Block
   yum install dhcpd

3. Do the steps in Configuring a DHCP Server

DHCP Server with DHCP Relay

In this configuration you can use the DHCP Server on the Abiquo Remote Services machine. Or you can install a separate DHCPD server.

There are two ways to install the DHCP Relay Server: Abiquo ISO and manual install.

• Abiquo ISO: see Automatically Configuring One DHCP Relay Server.
• Manual Install: see Manually Configuring One DHCP Relay Server

DHCP Server with Multiple DHCP Relays

In this configuration you can use the DHCP Server on the Abiquo Remote Services machine. Or you can install a separate DHCPD server.
See Manually Configuring Multiple DHCP Relay Servers.

• By default, the manual configuration is for multiple networks with separate VLAN tags
• There are a multitude of possible network configurations, so Abiquo does not recommend any specific configuration 

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) must have one interface with IP in the VLAN that will identify the VLAN in the DHCP Server. 

To configure a single DHCP server with VLAN support, see Configuring a DHCP server . 

To install a DHCP Relay server with the Abiquo appliances 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

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DHCP

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Server

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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 used for the VNICs or NICs 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 .