The PRP topology presented here is a reference system for process bus usage with switches supporting IEEE 1588 v2. This topology includes duplicated star networks which are called LAN A and LAN B. IEEE 1588 v2 clock masters are connected to the network using Ethernet switches. LAN A is presented with dark red lines and LAN B with light red.
In PRP, LAN A and LAN B must be connected only to end devices supporting PRP otherwise Ethernet communication is disturbed and might not work. All devices connected to both LAN A and LAN B must support the PRP protocol. Single attached nodes can be connected directly to LAN A or LAN B, in which case there is no redundancy for these nodes, or with a separate redundancy box (RedBox).
Note: Use correct Ethernet ports in the protection relay with PRP. Protection relays with PRP support have three Ethernet ports and redundant Ethernet ports are marked as X1/LAN A and X2/LAN B. The X3 Ethernet port is an interlink port which is used as a redundancy box connector.
Note: Do not mix different PRP LANs. Ensure that the LAN A port is always connected to LAN A only and the LAN B port is connected to LAN B.