FRER Configuration, Setup, and Status - Seeking Monitoring Guidance
I'm implementing a Fault-Tolerant Redundancy (FRER, IEEE 802.1CB) configuration across two switches and two end devices (AM62p boards) to establish a redundant ring network.
I've observed the status counters on the Listener switch and now seek advice on the best way to monitor the replicated data transmission across the FRER ring using a host port,
specifically via Wireshark on Switch 1.
The core question is: How can I observe the data duplication (replication) that FRER creates, given that the Listener switch (Switch 2) removes the duplicate frames before they reach the end device (AM62p board 2)?
1. Network Configuration Overview
The setup consists of an FRER ring connecting two switches (Switch 1 and Switch 2), with the Talker (AM62p brd 1) connected to Switch 1 and the Listener (AM62p brd 2) connected to Switch 2.
1.1. Switch 1 (Talker Side)
Component Configuration Details
FRER Config Unicast/Multicast Miss Config: Port 1 and Port 2 set to 0.
Stream Table: For Ports 1, 2, 3. Identification Type: Source MAC / VLAN. VLAN: 100. Source MAC: 08-04-b4-31-12-42.
Talker Configuration: On Port 3 (connected to AM62p brd 1).
VLAN Config VLAN 100: Learn and forward for Ports 1, 2, 3.
MSTP Exception VLAN 100 added to the MSTP exception list.
1.2. Switch 2 (Listener Side)
Component Configuration Details
FRER Config Unicast/Multicast Miss Config: Port 0 and Port 1 set to 0.
Stream Table: For Ports 0, 1, 2. Identification Type: Source MAC / VLAN. VLAN: 100. Source MAC: 08-04-b4-31-12-42.
Listener Configuration: On Port 2 (connected to AM62p brd 2).
VLAN Config VLAN 100: Learn and forward for Ports 0, 1, 2.
MSTP Exception VLAN 100 added to the MSTP exception list.
1.3. End Devices
Device Configuration Details
AM62p brd 1 (Talker) VLAN ID 100 created and IP configured. Runs simple client to generate traffic. Source MAC: 08-04-b4-31-12-42.
AM62p brd 2 (Listener) VLAN ID 100 created and IP configured. Runs simple server to receive data via VLAN 100. Crucially, no duplicate data is received.
2. Observed FRER Status (Switch 2 - Listener)
The status counters on the Listener Switch (Switch 2) demonstrate the FRER functionality, specifically the sequence reconciliation logic.
2.1. Status with Both Ethernet Ports Connected (Redundant Path Active)
Counter Value Interpretation
Passed-pkts 114 Packets successfully forwarded to the Listener device.
Discarded-pkts 342 Significantly high count. These are the replicated frames discarded by the Sequence Reconciliation Function as they were duplicates of frames already received and passed. → This confirms the data duplication and reconciliation is working.
Out-of-order-pkts 0
Rogue-pkts 0
Lost-pkts 0
2.2. Status with One Cable Removed (Single Path Active)
Counter Value Interpretation
Passed-pkts 36 Packets successfully forwarded. (Fewer total packets due to reduced test duration/traffic).
Discarded-pkts 0 As expected. With only one path, no duplicate frames arrive, and thus no packets are discarded by the reconciliation function.
Out-of-order-pkts 0
Rogue-pkts 0
Lost-pkts 0
3. Monitoring Question and Proposed Approach
The status counters confirm that Switch 1 is replicating the traffic and Switch 2 is reconciling it. However, since the duplicate frames are removed at Switch 2, I cannot capture the duplicated data on the AM62p brd 2.
Critical Negative Observation During Monitoring Attempt:
When I configured a host port on Switch 1 for monitoring and set it as a standard "learn and forward" port while mirroring traffic from the ring ports:
The entire network bandwidth was severely reduced.
The switch started flooding (dumping) data out of many ports.
This behavior is consistent with MAC address flapping caused by the two identical,
replicated frames (Stream A and Stream B, both from MAC: 08−04−b4−31−12−42) hitting the switch's MAC address table via the two mirrored ports simultaneously.
Question:
What is the recommended method to monitor the duplicated traffic (the two distinct streams of identical, sequenced packets) that is traversing the FRER ring?
