System, computer program, computer-readable medium and method for providing a redundant relay, particularly a routing function

A system for providing redundant relay comprising routing, functions, the system comprising;

• a plurality of redundant relays which connect or can connect a higher-level subnetwork to a lower-level subnetwork, wherein each redundant relay of the plurality of redundant relays including a relay redundancy controller;
• wherein the system is configured such that a maximum of one redundant relay of the plurality of redundant relays is ever operated in an active mode, while at least one remaining redundant relay of the plurality of redundant relays is in a standby mode, and if a currently active relay fails then the redundant relay or precisely one redundant relay of the at least one remaining redundant relay of the plurality of redundant relays is activated;
• wherein each redundant relay of the plurality of redundant relays comprises a DHCPv6 client for performing a prefix delegation and a relay controller;
• and
• wherein the system is further configured such that only a DHCPv6 client of a currently active relay ever performs the prefix delegation, and such that the relay redundancy controller of the respective relay signals the current relay mode to the relay controller of the respective relay, and the relay controller of the respectively active relay synchronizes at least one of (i) a virtual DUID of its DHCPv6 client and (ii) a prefix delegated to the active redundant relay to the or each redundant relay which is in a standby mode and, based on failure of the relay redundancy controller of the currently active relay fails to receive messages cyclically transmitted from the relay redundancy controller of the at least one remaining relay of the plurality of redundant relays being operated in the standby mode, the relay controller of the redundant relay activated in reaction to the failure starts the DHCPv6 client thereof, and the DHCPv6 client resorts to at least one of (i) the DHCP unique identifier (DUID) obtained via the synchronization and (ii) the prefix obtained via the synchronization.

A non-transitory computer-readable medium comprising computer program instructions which, when executed by a processor on at least one computer, causes the at least one computer to provide redundant relay functions in a network in which a higher-level subnetwork is connected to a lower-level subnetwork via at least a plurality of redundant relays, a maximum of one redundant relay of the plurality of redundant relays being operated in an active mode, while at least one remaining relay of the plurality of redundant relays being operated in a standby mode, each redundant relay of the plurality of redundant relays having a relay redundancy controller for controlling the relay mode, and the least one remaining relay or precisely one remaining redundant relay of the plurality of redundant relays being activated if a currently active relay of the plurality of redundant relays fails, the computer program instructions comprising:

• program code for performing, by only a DHCPv6 client of a currently active relay, a prefix delegation, each of the plurality of redundant relays including a DHCPv6 client for performing the prefix delegation and the plurality of redundant relays each including a relay controller to which the relay redundancy controller of a respective relay signals the current relay mode;
• program code for synchronizing, by the relay control module of the respectively active relay, a virtual DHCP unique identifier (DUID) of at least one of (i) a respective DHCPv6 client and (ii) a prefix delegated to the active relay to the or each relay which is in the standby mode;
• program code for starting, by a relay controller of a relay activated in reaction to a failure, the respective DHCPv6 client thereof based on failure of the relay redundancy module of the currently active relay to receive messages cyclically transmitted from the relay redundancy module of the at least one remaining relay of the plurality of redundant relays being operated in the standby mode;
• and
• program code for resorting, by the DHCPv6 client, to at least one of (i) the DUID obtained via the synchronization and (ii) the prefix obtained via the synchronization.