Operational Notes - Emerson PNC001-A Series Important Product Information

GFK-2573AB

Operational Notes

Operational Note
Storing updated media
redundancy protocol (MRP)
configurations to large operating
MRP ring networks with fast IO
update rates configured can
result in PROFINET I/O device
Loss/Add faults
Data packets arriving on ports
blocked by Media Redundancy
Protocol (MRP) still forwarded
over mirrored ports
Network monitoring devices
should be directly connected to
mirrored PNC001 ports
PROFINET IO Device Loss/Add
Faults for 3rd party I/O devices
may occur on hardware
configuration store in some large
network configurations
Description
When storing Media Redundancy Protocol (MRP) configuration updates to an operating
MRP ring network, users may infrequently observe one or more pairs of Loss of Device and
subsequent Addition of Device faults regarding PROFINET I/O Device faults on the network.
This is expected behavior and is more likely to occur on ring networks with a large number
of PROFINET I/O Devices acting as MRCs with very fast I/O Update Rates configured.
Because changing MRP configuration settings require each MRC to break and reconnect its
connections to the ring network, IP packets on the network may be lost as this flurry of
connection breaks/ reconnects occur on the network. Since a PROFINET I/O Device is
considered lost if it misses three consecutive I/O data transactions if three consecutive I/O
data packets from a particular PROFINET I/O Device are lost due to network
reconfiguration, the device will appear to be lost to the PNC001 and a Loss of I/O Device is
logged. When the network stabilizes, the PNC001 will be able to re-establish connection
with the lost IO Device and an Addition of I/O Device fault will be logged.
When a network is configured for MRP operation, MRCs and Media Redundancy Managers
(MRMs) can put one of their ring ports into a Blocking state. MRP uses this blocked port
state to break the continuous ring and allow only MRP management traffic to pass through
the blocked port. All of the non-MRP management traffic is blocked from ingress or egress
of the blocked port. If the port has been set up using the port mirroring monport command,
to monitor traffic on the blocked port, all of the traffic that arrives at the blocked port is
mirrored to the configured monitor port regardless of whether or not the traffic is MRP
management traffic. This makes it appear that the traffic is being sent or received on the
blocked port even though it is not.
When using the port mirroring monport command to monitor Ethernet traffic, you should
directly connect your PC/Laptop to the port on the PNC001 that is monitoring the traffic. If
there is an intervening switch in the mirrored path, the mirrored traffic will corrupt the
intervening switch's routing table. A corrupted routing table can cause dropped Ethernet
packets, resulting in the loss of PROFINET I/O and/or other Ethernet communication.
When storing hardware configurations with more than 64 PROFINET I/O Devices that
include multiple PNC001 modules and 3rd party PROFINET I/O Devices on a single network,
occasional Loss/Addition of I/O Device faults may be logged for some 3rd Party PROFINET I/O
devices. The devices should operate normally after being re-acquired by their controlling
PNC001 module. The Loss/Addition faults can be disregarded.
Jul 2022
18