GE Multilin L30 Line Current Differential System 5-315 SETTINGS 5.2 PRODUCT SETUP5a redundant or backup link to the network for port 2. Once Port 2 detects that the link between port 2 and the switch isgood, communications automatically switch back to port 2 and port 3 goes back into standby mode.If REDUNDANCY is set to PRP, the operation of ports 2 and 3 is as follows:• Ports 2 and 3 use the port 2 MAC address, IP address, and mask• The configuration fields for IP address and mask on port 3 are overwritten with those from port 2. This is visible on thefront panel but not displayed in the EnerVista software.• Port 2 MCST ADDRESS field is visible• The port 2 PTP function still uses only port 2 and the port 3 PTP function still uses only port 3. The relay still synchro-nizes to whichever port has the best master. When ports 2 and 3 see the same master, as is typically the case for PRPnetworks, the port with the better connectivity is used.The two ports must be connected to completely independent LANS with no single point of failure, such as commonpower supplies that feed switches on both LANS.For this setting change to take effect, restart the unit.PRT2 PRP MCST ADDR: This setting allows the user to change the multicast address used by the PRP supervision frames.This setting is available if REDUNDANCY is set to PRP. All devices in the same PRP network need to have the same multi-cast address. Choose an address that does not conflict with another multicast protocol.e) FAR-END FAULT INDICATION (FEFI)Since 100BASE-FX does not support Auto-Negotiation, a Far-End Fault Indication (FEFI) feature is included in UR 7 thatallows for detection of link failures.The purpose of the Far-End Fault feature is to allow the stations on both ends of a pair of fibers to be informed when thereis a problem with one of the fibers. Without the Far-End Fault feature, it is impossible for a fiber interface to detect a prob-lem that affects only its transmit fiber.When the Far-End Fault feature is supported, a loss of receive signal (link) causes the transmitter to generate a Far-EndFault pattern in order to inform the device at the far end of the fiber pair that a fault has occurred.When the local receiver again detects a signal, the local transmitter automatically returns to normal operation.If a Far-End Fault pattern is received by a fiber interface that supports the Far-End Fault feature and it is enabled, it reactsby dropping the link as if there were no signal at all.If the receiving interface does not support the Far-End Fault feature or has it disabled, an incoming Far-End Fault pattern isignored.It is strongly recommended to have switches used at substation automation support the Far-End Fault feature, especiallywhen UR 7 redundancy Failover is selected for redundancy purpose.f) PARALLEL REDUNDANCY PROTOCOL (PRP)The Parallel Redundancy Protocol (PRP) defines a redundancy protocol for high availability in substation automation net-works. It applies to networks based on Ethernet technology (ISO/IEC 8802-3) and is based on the second edition (July2012) of the IEC 62439-3, clause 4.PRP is designed to provide seamless recovery in case of a single failure in the network, by using a combination of LANduplication and frame duplication technique. Identical frames are sent on two completely independent networks that con-nect source and destination. Under normal circumstances both frames reach the destination and one of them is sent up theOSI stack to the destination application, while the second one is discarded. If an error occurs in one of the networks andNOTE
