One of the fundamental elements of the security system LAN-RING is fast data forwarding to a back-up line. Since 2008, this function has been performed by LAN-RING.v1 protocol with a switchover time of 30ms from the failure. Each ring in the system has a unique ID and one switch with the MASTER function (controls the ring). The higher port of the MASTER switch is normally set to a BLOCKING mode, hence preventing a loop. A port in BLOCKING mode receives only LAN-RING frames and blocks the other data (back-up line). If a failure occurs, the state of the blocked port changes to FORWARDING and starts to transmit all data.
During the failure creation and resolution, there are 2 short interruptions in the route. The second interruption provides the switchover from the back-up line back to the MASTER switch. Since, the end of 2014, a new innovative version of LAN-RING.v2 is available. The switch which has the MASTER function which controls the ring. In the case of a failure the MASTER function moves to the switch next to the failure. From the origin of the problem to the time of its removal, only one interruption occurs of up to maximum of 30ms.
The switchover time to the back-up line is for LAN-RING protocols slightly dependent on the number of switches connected in the ring. With each switch connected to the ring, the reconfiguration time increases by only about 6μs!
The table below shows an example of switchover times measured during testing at Prague’s University ČVUT and in METEL’s laboratory.