ALIF: Adding Backup and Satellite AIM's

Overview

This document describes how to add a Backup AIM to a Primary AIM Server. Adding a Backup AIM provides redundancy and allows the Infinity endpoints (TX’s & RX’s) to continue to operate and channel change in the event of an AIM failure.

From AIM firmware 4.1 and above, the ability to support endpoints on different subnets was added. This allows Infinity to be scaled up to thousands of endpoints. In order to implement the multi-subnet feature, a DHCP Server is required to issue IP Addresses to the endpoints and let them know where to find the AIM Servers.

The DHCP Server can either be provided by AIM itself when set in non-subnet mode or via an external DHCP Server when AIM is set to subnet mode. Multi-Subnet mode is a decision that is made when initially configuring the Primary AIM from a factory reset state, see How to Factory Reset an AIM for instructions.

This document does not cover how to configure an external DHCP server as there are many servers and configuration methods. It also assumes that you have some DHCP configuration knowledge and that the chosen Server can support DHCP Option 125.

AIM Terminology

Primary – Is the Master server.
Backup – A server on the same subnet as the Primary for redundancy.
Satellite – Is a backup server, but on a different subnet to the Primary.

The Backup and Satellite AIM’s hold a synchronized copy of the Primary AIM’s configuration/database. However, neither can change the configuration of the endpoints. Only the Primary can change the configuration including Adding/Removing Endpoints, Channels and Presets.

In order to have Satellite AIM’s on different subnets, the Primary AIM must be configured in Multi-Subnet mode.

Prerequisites

To add a Backup or Satellite AIM it is important that:-

• The Primary AIM is set to "Primary" and not "Solo".
• All AIM’s must be running the same firmware version.
• The End Point License must be the same on all the AIM’s.
• The Cluster Authentication on the Primary AIM must be disabled.
• The Backup/Satellite AIM Servers must be in a fully reset factory state before connecting it to the network. See How to Factory Reset an AIM.
• The date and time should be set the same. They don't have to be to second-accurate,, but should close.
• Require SSL for Web is not set on the Primary in the network settings.
• Satellite AIM’s are only supported from firmware version 4.2.37829 and above. The Primary must be configured in multi-subnet mode to support Satellite AIM's.

When adding a Backup it is important that:-

• The Primary AIM’s IP Address is not set to the last IP address in the range e.g. x.x.x.254. The Backup AIM will be given the next available IP address after the Primary, if the Primary is at the end of the range the Backup cannot be added.

When adding a Satellite it is important that:-

• The IP address(s) that will be assigned to the Satellite AIM(s) are included in the DHCP Option 125.

Adding a Backup AIM

A Backup AIM is a server that exists on the same subnet as the Primary. In order to add the Backup AIM you must ensure:-

• It is running the same firmware version.
• They have the same number of end point licenses.
• The Backup AIM is in a fully factory reset condition.
• You connect Port 1 of the Backup AIM to the same as the Primary AIM network 
  

How it Works

When an AIM boots for the first time, it carries out a number steps to check for the presence of other AIM’s on the network.

The first check is to find a Primary AIM on the same subnet whose fixed link-local network address is 169.254.1.2. If discovered it will request an IP address from the Primary AIM. This is typically the next available IP address, for example if the Primary is 192.168.1.1 then the Backup AIM is likely going to be assigned 192.168.1.2.

Once the Backup has been given its network settings from the Primary AIM, a TLS (Transport Layer Security) trust relationship is established between the two using private and public keys. This is used to encrypt the communications between the AIM’s and Endpoints.

The database will be synchronised between the Primary to Backup AIM. Depending on the size of the database this can take anything up to 10 minutes to complete. During this period, you can access the Primary AIM’s web interface and see the status in under the Servers tab. Whilst synchronising the status will be shown as ‘Initialising’, however once completed this will change to ‘Standby’.

Example: Server Configuration page.

How to set up a Backup AIM

The default IP address for the AIM is 169.254.1.3. It is highly recommended that you directly connect to the Backup AIM whilst initially setting it up. This is to prevent the Primary AIM from taking control prematurely.

Step 1: Upgrade/Downgrade the firmware if necessary. You can find the current version of AIM firmware installed at the bottom web interface. To upgrade navigate to Dashboard -> Updates. Upload the appropriate AIM firmware and reboot when requested.

Step 2: Check that the end point license is the same on the Primary and soon to be Backup AIM. Navigate to Dashboard -> Settings -> General. At the bottom for the page is a License section that tells you the number of supported devices. It is very important that they are the same. You can purchase additional end point licenses if required, please speak to your nearest Adder reseller or distributor.

Step 3: The cluster authentication must be disabled on the Primary AIM. Navigate to Dashboard -> Settings -> Servers on the Primary AIM. Click on No for Require Authentication and press Save.

Step 4: Perform a full Factory reset on the Backup Manager. Please see the How to Factory Reset an AIM section for instructions. Shutdown the Backup AIM.

Step 5: Connect the Backup AIM to the Primary AIM’s network and turn it on. Upon boot, the Primary AIM will automatically take control of the Backup AIM. It will assign it the next available IP address above its own.

Step 6: You can check the progress by viewing the Servers page on the Primary AIM. During the database synchronisation the status for the Backup AIM will be ‘Initialising’. Once complete it will say ‘Standby’. It can take anything up to ten minutes to for the synchronisation to complete. In this time it is not recommended that you reboot either the Primary or Backup AIM servers.

If you log in to the Backup AIM’s web interface you will see that the Backup Server is receiving updates from Primary.

Adding a Satellite AIM

In order to add a Satellite AIM on a different subnet to the Primary AIM you must ensure the following:-

• The Primary AIM is running in Multi-Subnet mode.
• The Satellite AIM is in a fully factory reset condition.
• It is running the same firmware version.
• They have the same number of end point licenses.
• There is DHCP Server on the Subnet that is capable of issuing Option 125.
• The Subnet’s routing allows it to see the Primary AIM’s subnet.
• Do not reserve the IP address that you will use for the Satellite AIM in the DHCP server.
• Exclude the IP address that you will use for the Satellite AIM from the DHCP Pool.

How it Works

When an AIM Server boots for the first time it will go through a number of steps to determine the world around it, for example check for the presence of another AIM Server and its role.

If a Primary AIM is not discovered on the same subnet then it will attempt to acquire an IP Address from a DHCP Server. If found, it will temporarily accept the IP address including the subnet mask, gateway and DNS settings and read the custom DHCP option 125 value, if present.

It cycles through the IP addresses in option 125 to see whether any are in the same subnet as its temporarily assigned DHCP network settings. If one is found it will check to see if it is available and not being used by another AIM. Provided it is free it will automatically configure itself by statically setting the IP address and using the subnet mask, gateway and DNS acquired via DHCP.

The Satellite will establish a connection to the Primary where an exchange of TLS (Transport Layer Security) keys will occur to ensure that communications are encrypted and the Primary AIM’s database is synchronised. Depending on the size of the Primary’s AIM’s database, the process can take up to 10 minutes to complete, during which you can check the status on the Primary AIM’s ‘Servers’ page. It will say ‘Standby’ when complete.

Example: Server Configuration page.

How to set up a Satellite AIM

The default IP address for the AIM is 169.254.1.3. It is highly recommended that you directly connect to the Satellite AIM whilst initially setting it up. This is to prevent the Primary AIM from taking control prematurely.

Step 1: Setup the DHCP Server. You must choose an IP Address for the Satellite AIM, one that is out of the DHCP pool scope on the subnet. The chosen IP address needs to be added to DHCP option 125 on all the DHCP Servers that service the Infinity network. Please read the Understanding DHCP Option 125 section of this document.

Step 2: Upgrade/Downgrade the firmware if necessary. You can find the current version of AIM firmware installed at the bottom web interface. To upgrade navigate to Dashboard -> Updates. Upload the appropriate AIM firmware and reboot when requested.

Step 3: Check that the end point license is the same on the Primary and soon to be Satellite AIM. Navigate to Dashboard -> Settings -> General. At the bottom for the page is a License section that tells you the number of supported devices. It is very important that they are the same. You can purchase additional end point licenses if required, please speak to your nearest Adder reseller or distributor.

Step 4: The cluster authentication must be disabled on the Primary AIM. Navigate to Dashboard -> Settings -> Servers on the Primary AIM. Click on No for Require Authentication and press Save.

Step 5: Perform a full Factory reset. Please see the How to Factory Reset an AIM section for instructions. Shutdown the Satellite AIM.

Step 6: Connect the Satellite AIM to the Infinity subnet and turn it on. Upon boot, the Satellite AIM will establish its IP Address from Option 125 in the DHCP Server and make contact with the Primary AIM.

The Primary AIM will synchronise its database with the Satellite, during which you can monitor its progress viewing the Servers page on the Primary AIM. The Satellite AIM will show ‘Initialising’ during the synchronisation process and ‘Standby’ when it has finished. Depending on the size of the database, this can take anything up to ten minutes to perform.