ABB RELION 620 Series Technical Manual page 59

1MAC504801-IB E
620 series ANSI
Technical Manual
In case a laptop or a PC workstation is connected as a non-PRP node to one of the PRP
networks, LAN A or LAN B, it is recommended to use a redundancy box device or an
Ethernet switch with similar functionality between the PRP network and SAN to remove
additional PRP information from the Ethernet frames. In some cases, default PC
workstation adapters are not able to handle the maximum-length Ethernet frames with the
PRP trailer.
There are different alternative ways to connect a laptop or a workstation as SAN to a PRP
network.
• Via an external redundancy box (RedBox) or a switch capable of connecting to PRP
and normal networks
• By connecting the node directly to LAN A or LAN B as SAN
• By connecting the node to the protection relay's interlink port
Take care to ensure that the ports marked "LAN A" and "LAN B" are used
when implementing PRP. Some communication options offer a third port
which should not be used for redundant Ethernet connectivity.
In a PRP network, the installer should ensure that all of the LAN A ports
are connected to the same switch and that all of the LAN B ports are
connected to a different switch.
HSR
HSR applies the PRP principle of parallel operation to a single ring, treating the two
directions as two virtual LANs. For each frame sent, a node, DAN, sends two frames, one
over each port. Both frames circulate in opposite directions over the ring and each node
forwards the frames it receives, from one port to the other. When the originating node
receives a frame sent to itself, it discards that to avoid loops; therefore, no ring protocol is
needed. Individually attached nodes, SANs, such as laptops and printers, must be attached
through a "redundancy box" that acts as a ring element. For example, a 615 or 620 series
protection relay with HSR support can be used as a redundancy box.
Section 2
620 series overview
53