This article explains why the log message "cfmman_conn_disconnect:1002 disconnecting connection with cfmd" is shown on MX routers even when no CFM is configured and lists the steps to troubleshoot the message. These messages are for information purposes only and can be safely ignored.

Customer reported that the message log was flooded with "cfmman_conn_disconnect:1002 disconnecting connection with cfmd" log even when there was no CFM configuration on the device.

This log message is triggered when CFM opcode 43 (LMM) PDU and CFM opcode 47(DMM) PDU are received by the router. These CFM PDUs are sent to cfmman for processing, which then sends the PDUs to CFMD on the Routing Engine (RE). Since no CFM configuration exists on the device, cfmman floods the logs, which reports "disconnecting connection with cfmd".

This is as per design and the log is only for information purposes. There is no associated service impact due to the message.

To troubleshoot this issue, perform the following steps:

1. Add a syslog file to collect the PFE log.

#set system syslog file jtac-debug pfe any

2. Log in to member0-fpc3 pfe, change the debug cfm level to 4, and collect CFM debug logs.

>start shell pfe network member0-fpc3
#set syslog tty disable     <<< Add one more command, in case more debug log flooding is seen in output.
#debug cfm level 4

Wait for 10~20 seconds.

#debug cfm level 0

3. Check the jtac-debug file to see if any CFM opcode 43 and opcode 47 PDUs are received on the FPC.

>file list /var/log/jtac-debug
>file show /var/log/jtac-debug | match "opcode 43"
>file show /var/log/jtac-debug | match "opcode 47"
 
Nov 19 10:17:26.283 2020  router-re0 member0-fpc3 cfmman_proto_receive: opcode 47, pdu 0x469d4db8, pkt_len 60, frame_start 0xb4d46f6f, ether 0xb4d46f6f, ether_hdr_offset 0, cfm_hdr 0xb4d46f81, cfm_hdr_offset 18 ifl_ix 3118
Nov 19 10:16:06.385 2020  router-re0 member0-fpc3 cfmman_proto_receive: opcode 43, pdu 0x5e701820, pkt_len 60, frame_start 0xb5098317, ether 0xb5098317, ether_hdr_offset 0, cfm_hdr 0xb5098329, cfm_hdr_offset 18 ifl_ix 3118

4. With the ifl_ix number noted from the above output, log in to the FPC PFE and run show ifl 3118 to know the interface that is receiving the CFM opcode 43 or opcode 47 PDUs from the peer device. Then the peer device needs to be checked.

#show ifl xxx

5. After collecting debug logs, delete the configured command in step 1 to avoid generating more debug logs and increasing storage on the RE.

#delete system syslog file jtac-debug pfe any

Meanwhile, there are two options to stop this these messages from flooding the log:

1. Since the log is at syslog info level, changing the syslog level to debug should stop the log from flooding.

2. Configuring a syslog filter will help filter the log in the messages.

See KB22177 - [EX] How to filter two or more specific messages from being written to the syslog file [juniper.net] .