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  1. RHEL
  2. RHEL-72445

GSM usb modem ip disappearing after sometime and device deactivation reason 'unmanaged-link-not-init'

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    • NMT SST - 2025Q1
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      Definition of Done:

      Please mark each item below with ( / ) if completed or ( x ) if incomplete:

      ( ) The acceptance criteria defined below are met.

      Given a system administrator connects a 5G USB modem to a system running NetworkManager and ModemManager,

      When they configure the modem to acquire an IP address via DHCP,

      Then NetworkManager should maintain the assigned IP address and DHCP lease, and it should not remove the device’s profile due to incorrect state assessments (e.g., unmanaged-link-not-init) as long as the modem remains operational and visible to ModemManager.

      Definition of Done:

      • The implementation meets the acceptance criteria
      • Integration tests are written and pass 
      • The code is part of a downstream build attached to an errata

      ( ) Code changes are included in a downstream build attached to an errata.

      ( ) All required testing (manual and/or automated) passes successfully.

      ( ) Related documentation updates (if applicable) have been completed.

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      Definition of Done: Please mark each item below with ( / ) if completed or ( x ) if incomplete: ( ) The acceptance criteria defined below are met. Given a system administrator connects a 5G USB modem to a system running NetworkManager and ModemManager, When they configure the modem to acquire an IP address via DHCP, Then NetworkManager should maintain the assigned IP address and DHCP lease, and it should not remove the device’s profile due to incorrect state assessments (e.g., unmanaged-link-not-init) as long as the modem remains operational and visible to ModemManager. Definition of Done: The implementation meets the acceptance criteria Integration tests are written and pass  The code is part of a downstream build attached to an errata ( ) Code changes are included in a downstream build attached to an errata. ( ) All required testing (manual and/or automated) passes successfully. ( ) Related documentation updates (if applicable) have been completed.
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      Issue :

      Customer attaches 5G USB modem and ip address is assigned via DHCP. After sometime (from what i saw when lft reaches the lease time), the ip is removed from interface.

      Components :

      • NetworkManager 1.48.10-2
      • ModemManager 1.20.2-1
      • Modem : Telit Wireless Solutions FN990

      Analysis/Observation :

      • As the SOM board boots, the ip is assigned properly on interface enp0s20f0u1.
      • The lft on interface is 43200 (i.e 12hrs)
      • After ~12hrs the ip is being removed.
      Dec 23 17:39:09 rtis NetworkManager[1023]: <info>  [1734955749.5088] dhcp4 (enp0s20f0u1): state changed new lease, address=192.168.225.124
Dec 23 17:39:09 rtis avahi-daemon[870]: Registering new address record for 192.168.225.124 on enp0s20f0u1.IPv4.
Dec 24 05:39:10 rtis avahi-daemon[870]: Withdrawing address record for 192.168.225.124 on enp0s20f0u1.
      • Lets look for logs when the system boots and assigns address for first time.
      // Dynamic address on enp0s20f0u1 is assigned. NM creates it default config.
Dec 27 10:35:58 rtis NetworkManager[1023]: <debug> [1735275958.5906] device[b842ae14b45cf96e] (enp0s20f0u1): ifindex: set ifindex 2 (l3cfg: 16c0dcf37359ce99)
Dec 27 10:35:58 rtis NetworkManager[1023]: <trace> [1735275958.5933] settings: auto-default: creating in-memory connection 25bf1d55-e11e-3214-90a4-a7ef8ae08442 (Wired connection 2) for device enp0s20f0u1

// Ipaddress is assigned on interface via dhcp.
Dec 27 10:36:06 rtis NetworkManager[1023]: <debug> [1735275966.8431] dhcp4 (enp0s20f0u1): event: received ACK of 192.168.225.124 from 192.168.225.

// Later within few seconds, the same device is deactivated with result.
Dec 27 10:36:18 rtis NetworkManager[1023]: <debug> [1735275978.4664] device[b842ae14b45cf96e] (enp0s20f0u1): deactivating device (reason 'unmanaged-link-not-init') [71]

// The configuration is removed.
Dec 27 10:36:18 rtis NetworkManager[1023]: <trace> [1735275978.4665] l3cfg[16c0dcf37359ce99,ifindex=2]: IP configuration changed (mark dirty): configuration removed

// dhcp is stopped.
Dec 27 10:36:18 rtis NetworkManager[1023]: <trace> [1735275978.4665] dhcp4 (enp0s20f0u1): dhcp-client4: stop 63156036fe1a8c5e
Dec 27 10:36:18 rtis NetworkManager[1023]: <trace> [1735275978.4699] settings: auto-default: forget association between 25bf1d55-e11e-3214-90a4-a7ef8ae08442 (Wired connection 2) and device enp0s20f0u1 (temporary)

// Profile is deleted.
Dec 27 10:36:18 rtis NetworkManager[1023]: <trace> [1735275978.4700] keyfile: commit: deleted "/run/NetworkManager/system-connections/Wired connection 2.nmconnection", profile 25bf1d55-e11e-3214-90a4-a7ef8ae08442 (deleted from disk)
Dec 27 10:36:18 rtis NetworkManager[1023]: <trace> [1735275978.4700] settings: update[25bf1d55-e11e-3214-90a4-a7ef8ae08442]: delete connection "Wired connection 2" (dca6a30d7a82a3e5/keyfile)
      • Now analysing further on what happens before NM removes device due to 'unmanaged-link-not-init'.
      Dec 27 10:36:18 rtis ModemManager[920]: <info>  [modem0] state changed (unknown -> disabled)
Dec 27 10:36:18 rtis ModemManager[920]: <debug> [modem0] modem initialized
Dec 27 10:36:18 rtis ModemManager[920]: <debug> [device /sys/devices/pci0000:00/0000:00:14.0/usb2/2-1]  exported modem at path '/org/freedesktop/ModemManager1/Modem/0'
Dec 27 10:36:18 rtis ModemManager[920]: <debug> [device /sys/devices/pci0000:00/0000:00:14.0/usb2/2-1]     plugin:  telit
Dec 27 10:36:18 rtis ModemManager[920]: <debug> [device /sys/devices/pci0000:00/0000:00:14.0/usb2/2-1]     vid:pid: 0x1BC7:0x1072
Dec 27 10:36:18 rtis ModemManager[920]: <debug> [ttyUSB2/at] device open count is 1 (close)

[..]

Dec 27 10:36:18 rtis NetworkManager[1023]: <debug> [1735275978.4658] device[c5e247b7c0983d89] (ttyUSB2): unmanaged: flags set to [platform-init,!user-settings=0x4/0x14/unmanaged/unrealized], set-managed [user-settings=0x10])
Dec 27 10:36:18 rtis NetworkManager[1023]: <debug> [1735275978.4658] device[c5e247b7c0983d89] (ttyUSB2): unmanaged: flags set to [!platform-init,!user-settings=0x0/0x14/managed/unrealized], set-managed [platform-init=0x4])
Dec 27 10:36:18 rtis NetworkManager[1023]: <debug> [1735275978.4661] manager: (enp0s20f0u1): removing device (managed 1, wol 0)
Dec 27 10:36:18 rtis NetworkManager[1023]: <trace> [1735275978.4661] device[b842ae14b45cf96e] (enp0s20f0u1): sys-iface-state: managed -> removed
      • During the remote session with customer, if i perform 'mmcli --list-modems' i can see the modem loaded pretty fine. Hence, i am unsure why does it shows reason 71 ? Also modem keeps working despite the NM profile is removed, only after some hrs the ip is removed.

      My thoughts :

      • The ip address is assigned fine, few seconds later NM notices NMDeviceStateReason 71 (device not initialized by udev), and thus it removes the temporary profile 'Wired connection x' attached to the device.
      • Now, after lft reaches close to dhcp lease time (here 43200 ~12hrs), the ip is removed as there is no NM profile to renew the lease.

       

      Help required :

      • While NM detects NMDeviceStateReason 71, i couldn't see any specific error for modem except a single line showing modem0 state changed to disabled. What exactly does NM looks to confirm the device state ?
      • Could you please help me understand the real root cause why NM says NMDeviceStateReason 71, while modem is still loaded  and seen under mmcli.

       

      Attachment : sosreport-rtis-1-2024-12-27-tfseflu.tar.xz

      ( Contains debug logs of NM and MM since the boot )

        1. sosreport-rtis-1-2024-12-27-tfseflu.tar.xz
          14.68 MB
        2. sosreport-rtis-1-2025-01-21-mtgngfv.tar.xz
          670 kB

              rh-ee-sfaye Stanislas Faye
              rhn-support-arawal Abhishek Rawal
              Network Management Team Network Management Team
              Vladimir Benes Vladimir Benes
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                Created:
                Updated:
                Resolved: