Controlling a plurality of networked building technology devices

A system for controlling a plurality of networked building technology devices (IBTD, BTD1-BTD8), comprising lighting units, by sending messages over a network, the system comprising:

• a plurality of building technology devices (IBTD, BTD1-BTD8), wherein at least one building technology device (IBTD, BTD1-BTD8) is a lighting unit, and
• a network functionally connecting said building technology devices (IBTD, BTD1-BTD8),
• wherein at least one of the building technology devices (IBTD, BTD1-BTD8) is a message issuing device (IBTD) configured to send multicast or broadcast messages to a plurality of or all of the remaining building technology devices (BTD1-BTD8), wherein any multicast or broadcast message is an IPv4 or IPv6 message, and the remaining building technology devices are configured to change state or not depending on information contained in a received message,
• wherein the network is arranged such that at least three of the remaining building technology devices (BTD1-BTD8) are included in first ring network topology and at least three of the remaining building technology devices are included in a second ring network topology (UR1-UR3), and
• wherein the at least three remaining building technology devices in such ring network topologies (UR1-UR3) are configured to exchange unicast messages with neighboring devices in the respective ring network topology (UR1-UR3) and wherein said unicast messages are individually addressed to the respective neighboring device when sent and the respective neighboring device sends an acknowledgment to the sending device when the message is properly received;
• and further wherein
• the multicast, broadcast and unicast messages comprise a sequence number and the sequence number is increased or decreased by the message issuing device whenever a message is issued so that the sequence number can identify the age of the message depending on a counting scheme;
• the remaining building technology devices (BTD1-BTD8) are configured to evaluate a received unicast message on the condition that the age of the unicast message is younger than that of any previous message received the building technology device (IBTD, BTD1-BTD8);
• and
• the remaining building technology devices (BTD1-BTD8) are configured to verify whether at least one neighbor device has received a new message using unicast messages.