Troubleshooting multicast issues.

Introduction

The FCSDK in HA mode will use multicast & jgroups to share state. The master & slave nodes will join a jgroup via multicast and use that to share configuration changes.

If you ever find a problem where configuration seems to vanish from the WBF or you get random call failures then you may have a multicast problem.

Cause

If you have a multicast issue on your network (some switches have it turned off or it does not traverse subnets by default). Then the master & slave cannot discover each other and can have 2 separate configurations.

To test multicast between your master & slave nodes please see below:

1.Can you check you have iperf installed on both master & slave by typing iperf, If it comes back with command not found please install it as below:

2.On the slave run the iperf server:

  • iperf -s -u -p 7600 -B 224.0.75.75 -i 1

3.On the master run the iperf client:

iperf -c 224.0.75.75 -p 7600 -u -T 32 -i 1

You should see the following on the master (client):

# iperf -c 224.0.75.75 -p 7600 -u -T 32 -i 1
------------------------------------------------------------
Client connecting to 224.0.75.75, UDP port 7600
Sending 1470 byte datagrams
Setting multicast TTL to 32
UDP buffer size:  224 KByte (default)
------------------------------------------------------------
[  3] local 192.168.9.34 port 54654 connected with 224.0.75.75 port 7600
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 1.0 sec   129 KBytes  1.06 Mbits/sec
[  3]  1.0- 2.0 sec   128 KBytes  1.05 Mbits/sec
[  3]  2.0- 3.0 sec   128 KBytes  1.05 Mbits/sec
[  3]  3.0- 4.0 sec   128 KBytes  1.05 Mbits/sec
[  3]  4.0- 5.0 sec   128 KBytes  1.05 Mbits/sec
[  3]  5.0- 6.0 sec   128 KBytes  1.05 Mbits/sec
[  3]  6.0- 7.0 sec   129 KBytes  1.06 Mbits/sec
[  3]  7.0- 8.0 sec   128 KBytes  1.05 Mbits/sec
[  3]  8.0- 9.0 sec   128 KBytes  1.05 Mbits/sec
[  3]  9.0-10.0 sec   128 KBytes  1.05 Mbits/sec
[  3]  0.0-10.0 sec  1.25 MBytes  1.05 Mbits/sec
[  3] Sent 893 datagrams

And then on the slave (server):

iperf -s -u -p 7600 -B 224.0.75.75 -i 1
------------------------------------------------------------
Server listening on UDP port 7600
Binding to local address 224.0.75.75
Joining multicast group  224.0.75.75
Receiving 1470 byte datagrams
UDP buffer size:  224 KByte (default)
------------------------------------------------------------
[  3] local 224.0.75.75 port 7600 connected with 192.168.9.34 port 54654
[ ID] Interval       Transfer     Bandwidth        Jitter   Lost/Total Datagrams
[  3]  0.0- 1.0 sec   128 KBytes  1.05 Mbits/sec   0.054 ms    0/   89 (0%)
[  3]  1.0- 2.0 sec   128 KBytes  1.05 Mbits/sec   0.047 ms    0/   89 (0%)
[  3]  2.0- 3.0 sec   128 KBytes  1.05 Mbits/sec   0.053 ms    0/   89 (0%)
[  3]  3.0- 4.0 sec   128 KBytes  1.05 Mbits/sec   0.054 ms    0/   89 (0%)
[  3]  4.0- 5.0 sec   128 KBytes  1.05 Mbits/sec   0.094 ms    0/   89 (0%)
[  3]  5.0- 6.0 sec   129 KBytes  1.06 Mbits/sec   0.106 ms    0/   90 (0%)
[  3]  6.0- 7.0 sec   128 KBytes  1.05 Mbits/sec   0.064 ms    0/   89 (0%)
[  3]  7.0- 8.0 sec   128 KBytes  1.05 Mbits/sec   0.047 ms    0/   89 (0%)
[  3]  8.0- 9.0 sec   128 KBytes  1.05 Mbits/sec   0.038 ms    0/   89 (0%)
[  3]  9.0-10.0 sec   128 KBytes  1.05 Mbits/sec   0.060 ms    0/   89 (0%)
[  3]  0.0-10.0 sec  1.25 MBytes  1.05 Mbits/sec   0.067 ms    0/  893 (0%)

Resolution

Ensure a multicast is enabled between both nodes.

 

 

 

 

 

 

 

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