8. Backup connection addresses

The DynFi® Manager allows you to specify more than one connection address for a device. These extra backup addresses will be used by the DynFi Manager when connectiong via the main/primary connection address is no longer possible.

8.1. Main connection address

To attach a device to the DynFi Manager (so it can be managed) the DFM needs to connect to the device. At least one address must be specified and it must be functional during the initial device setup. This address can be an IP address or a domain name.

In addition the address, the user must specify the port on which the device listens for incoming SSH connections.

8.2. Backup connection addresses

In addition to specifying the main connection address (which is mandatory and validated), a user can specify up to ten optional backup addresses. These backup addresses are not validated at the time of entry. They can be added or deleted at any time, not just during device creation. Each backup address can specify a different port.

It is possible to set the order of backup addresses or replace the main address with one of the backups. The initial main address can be deleted if is replaced by a backup address - it doesn’t have any special significance beyond being the first address on the list.

8.3. Switching to another address in case of failure

All addresses (main and backup) form a list of addresses that DynFi Manager will try when establishing a connection for a given device. If this list contains more than one address (i.e. backup addresses are present) and the connection to the device fails, the next address on the list is promoted as the “used connection address”. (For the last address on the list, the connection attempt will loop back to the first one.) However, the next connection attempt is not made immediately but follows the anti-lockout policy. Switching to a backup address doesn not permanently reorder of the list - DynFi Manager will try to reconnect using the main address.

8.4. Manually switching to another address

It is possible to manually switch to any address from the list of the defined addresses at any time. If there are no connectivity issues for the given device (i.e. the anti-lockout policy is not active), the selected connection address will be used immediately. For devices with connectivity issues, the selected address will be used for the next connection attempt. This feature might be useful, for example, when maintenance is planned for the connection using the main address.

A manual switch is possible by clicking on the small green icon next to “Used connection address” in the device’s status pane (provided the device has any backup connection addresses defined). For devices with connectivity issues, a manual switch is also possible in the device’s edit form.

8.5. Automatic fallback to main connection address

By default, when using a backup connection address to reach a device, DynFi Manager will try to reconnect using the main connection address. This behaviour can be adjusted or disabled by modifying the configuration. Please refer to tryGoingBackToMainConnectionAddressEveryMinutes.

8.6. Uniqueness of the connection addresses

Each combination of the connection address (both main and backup) and port has to be unique within given DynFi Manager setup. For example, it is not allowed for one device to use example.com:22 as the main address while another device also uses example.com:22, (whether as main or backup address). However, th other device could use example.org:22 or example.com:123 though.