14. Backup connection addresses
The DynFi® Manager allows specifying more than one connection address for a device. These extra backup ones will be used by the DynFi Manager when the connection using the main/primary connection address is no longer possible.
14.1. Main connection address
To attach a device to the DynFi Manager (so it can be managed) the DFM needs to connect to the device. So at least one address has to be specified and need to work when adding the device. This can be an IP address or a domain name.
Beside the address, the user also needs to specify the port on which the device listens to incoming SSH connections.
14.2. Backup connection addresses
Apart from specifying the main connection address (which is obligatory and checked), a user can also specify up to ten optional and unchecked backup addresses. Backup addresses can be added or deleted at any time, not only during device creation. Each backup address can specify a different port, also different than the main address.
14.3. Switching to another address in case of failure
All addresses (main and backup) form a list of addresses to try when trying to establish a connection for given device. In case this list has more than one element (i.e. backup addresses are present), when the connection to the device fails, the next address from the list is promoted as the “used connection address”. (For the last address in the list, the jump is made to the first one.) However, the next connection attempt is not performed instantly but follows the anti-lockout policy.
14.4. Manually switching to another address
It is possible to switch manually at any time to any address from the list of the defined addresses. If there are no issues with connectivity for a given device (i.e. the anti-lockout policy is not active), the selected connection address will be used right away. For devices with connectivity issues, the selected address will be used for next connection attempt.
This might be useful when e.g. some maintenance of the connection using the main address is planned.
Manual switch is possible after click on the little green icon next to “Used connection address” in device’s status pane (provided the device specifies any backup connection addresses).
For devices with connectivity issues it is also possible in the device’s edit form.
14.5. Automatic fallback to main connection address
By default, when using a backup connection address to reach a device, the DynFi Manager will try to get back using the main connection address. This can be tuned or disabled by adjusting the configuration. Please refer to tryGoingBackToMainConnectionAddressEveryMinutes.
14.6. Uniqueness of the connection addresses
Each combination of the connection address (both main and backup) and port has to be unique in given DynFi Manager setup. E.g. it is impossible for one device to use example.com:22 as main address and for another device to also use example.com:22, either as main or as backup address. The other device can use example.org:22 or example.com:123 though.