GE Multilin 850 Instruction Manual page 160

DEVICE
NOTE:
4–28
The communications card comes with the capability of setting a number of static routes
and one default route, which is used instead of default gateways.
Notes:
• The fiber optic ports support only 100 Mbps.
• Changes to the Ethernet communications settings take effect only after rebooting the
relay.
• All Ethernet ports have flex operands associated with them. A failure of one of the
Ethernet ports will trigger an event, a target message and the corresponding operand
set.
PRT4 OPERATION
Range: Independent, LLA, PRP
Default: Independent
This setting determines the mode of operation for ports 4 and 5: INDEPENDENT, LLA or
PRP.
INDEPENDENT operation: ports 4 and 5 operate independently with their own MAC and
IP address.
LLA operation: the operation of ports 4 and 5 are as follows:
Ports 4 and 5 use port 4's MAC and IP address settings while port 5 is in standby mode in
that it does not actively communicate on the Ethernet network but monitors its link. If
Port 4 is active and the link loss problem is detected, communications is switched to Port
5 immediately. Port 5 is, in effect, acting as a redundant or backup link to the network
for port 4.
LLA (Link Loss Alert) is a proprietary feature supported by the 8 Series relay fiber optic
ports. When enabled on an 8 Series fiber optic port, this feature is able to detect a failure
of the fiber link. If port 4's OPERATION is set to LLA, the detection of a link failure by this
feature triggers the transfer of communications from port 4 to port 5. If LLA is enabled
on a port with a non-fiber SFP, the target message "LLA not supported by Prt (4 or 5)" is
displayed on the keypad and an event is logged.
PRP (Parallel Redundancy Protocol): ports 4 and 5 use the same MAC address and
combine information at the link layer. It is intended to only be used if the two ports are
connected to separate parallel LAN's. In this mode of operation both ports cannot be
connected to the same LAN. The receiving devices (850 ) process the first frame received
and discard the duplicate through a link redundancy entity (LRE) or similar service that
operates below layer 2. Aside from LRE, PRP uses conventional Ethernet hardware but
both ports must know they are in PRP. Ports of PRP devices operating with the same
Internet Protocol (IP) addresses for traffic that uses IP Management protocols such as
Address Resolution Protocol (ARP) must operate correctly.
Duplicate Discard mode (only mode supported by the 8 Series). This is the normal
setting for PRP operation and once set it allows the sender LRE to append a six-octet
field that contains a sequence number, the Redundancy Control Trailer (RCT) to both
frames it sends. The receiver LRE uses the sequence number of the RCT and the source
MAC address to detect duplicates. It forwards only the first frame of a pair to its upper
layers.
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS