After swapping the QSFP and fibre cables on channelized interfaces, the ports are still showing physically down. Additionally, the QSFPs connected to FPC0 have low-power alarms on the receiving side.
> show interfaces descriptions | match et-0/0/51 et-0/0/51:0 up et-0/0/51:1 down down et-0/0/51:2 up up et-0/0/51:3 up up > show interfaces | match et-0/0/59 Physical interface: et-0/0/59:0, Enabled, Physical link is Up Physical interface: et-0/0/59:1, Enabled, Physical link is Down Physical interface: et-0/0/59:2, Enabled, Physical link is Up Physical interface: et-0/0/59:3, Enabled, Physical link is Up
Troubleshooting Steps 1. Inspect Physical Connections - Ensure Proper Seating: Double-check that the QSFP module is properly seated in the port. - Verify Cable Connections: Verify that the fibre cables are securely connected to the QSFP module on both sides. - Test on Known Working Port: Test the current QSFP module and fibre cable on a known working port or device to confirm if the issue is not with the peer-end device. 2. Examine Link Status and Logs - Use commands to check the status of the ports: > show interfaces <et-> extensive >show log messages | match <et-> 3. Verify Configuration - Ensure that the port configuration is correct and matches the requirements for the QSFP module and fiber cable. 4. Perform Loopback Test - Perform hard loop and soft loopback tests by connecting a loopback cable or module to the QSFP port to verify if the port comes up. For instructions on performing loopback tests, refer to [Juniper's documentation on Ethernet loopback testing](https://www.juniper.net/documentation/us/en/software/junos/interfaces-ethernet/topics/topic-map/ethernet-fast-and-gigabit-loopback-testing.html). 5. Replace the Cable - Replace the cable with another working port on the peer end and check the status of the port. 6. Toggle Interfaces - Disable and then enable the interfaces and check the status. 7. Restart the FPC - Restart the FPC and check if the ports come up. 8. Enable Traceoptions for the Interface - Enable traceoptions for the interface to collect more information: set interfaces <Intf_name> traceoptions flag all set interfaces traceoptions file DCD files 20 size 200m set interfaces traceoptions flag all Additional Diagnostic Commands Collect these outputs from the chassis during the issuing state (before and after restarting the FPC): >show interface diagnostics optics <et-> start shell command "cprod -A fpc0 -c \"show qsfp <> diagnostics\"" | no-more start shell command "cprod -A fpc0 -c \"show mtip-chpcs summary\"" | no-more start shell command "cprod -A fpc0 -c \"show mtip-chmac 208 intr-registers\"" | no-more Shell Commands start shell % vty fpc0 # show syslog messages # show qsfp list # show qsfp <idx> alarms (Check for the index number from the above command for interface which was showing down state) # show t6e-pic 0 link-stats-summary # show t6e-pic 0 link-status <port channelized port> # show t6e-pic 0 link-mac-stats <port channelized port> By following these steps and collecting the specified outputs, we should be able to identify the cause of the issue and take appropriate action to resolve it. If the issue persists, consider contacting the JTAC support team for further assistance.