modem-m: LTE Modem LTE USB Nimblelink NL-SW-LTE-S7588

[Kyle Nitzsche]

A project reports there are no MBIM paths in /dev/ auto created for LTE Modem LTE USB Sierra (vendor is Nimblelink) NL-SW-LTE-S7588 on classic or core.

The modem is said to support either PPP or to present a full wlan interface, and the project requires the full wlan interface. Also, the project was told by Nimblelink to use NCM, not MBIM. (details below)

[Alfonso Sanchez-Beato (alfonsosanchezbeato)]

Apparently this is a Sierra HL7648: https://nimbelink.com/products/4g-lte-cat-1-att-sierra-wireless/

I do not see any reference to the Sierra HL7648 or Nimblelink in MM sources, output of "mmcli -m <N>" will show the plugin that MM is assigning to the modem, which will help with triaging.

[Jon Watson (jwatson-kdp)]

The feedback we received from Nimbelink was they recommend using the NCM configuration method (NOT to use MBIM) as per the directions for the NK-SW-LTE-S7588 modem.

Currently we are configuring the modem per this set of directions.

[Jon Watson (jwatson-kdp)]

Sorry, typo in my previous message.... Should have said:

  NL-SW-LTE-S7588 modem

NOT NK-SW-LTE-S7588 modem.

[Jon Watson (jwatson-kdp)]

I've attached the documents we used to configure the S7648 modem in NCM mode.

[Kyle Nitzsche (knitzsche)]

An internal list of known working modems with modem-manager includes Sierra HL7588, DW5815 (with MBIM).

[Jon Watson (jwatson-kdp)]

As requested here is the output from modemmanager about our modem:

ubuntu@ubuntu:~$ mmcli -L
    /org/freedesktop/ModemManager1/Modem/0 [Sierra Wireless] HL7648
ubuntu@ubuntu:~$ mmcli -m 0
  --------------------------------
  General | dbus path: /org/freedesktop/ModemManager1/Modem/0
           | device id: e758c92bbc1c13f82c9cf271815b8e659d70344a
  --------------------------------
  Hardware | manufacturer: Sierra Wireless
           | model: HL7648
           | firmware revision: SWIMCB71XX-AIM1.04.02.A14.164804.201802221656.01
           | supported: gsm-umts, lte
           | current: gsm-umts, lte
           | equipment id: 014697000106770
  --------------------------------
  System | device: /sys/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2
           | drivers: cdc_acm, cdc_ncm
           | plugin: Generic
           | primary port: ttyACM2
           | ports: wwan1 (net), wwan3 (net), wwan0 (net), wwan2 (net),
           | ttyACM2 (at), ttyACM0 (at)
  --------------------------------
  Status | unlock retries: sim-pin (3), sim-puk (10), sim-pin2 (3), sim-puk2 (10)
           | state: registered
           | power state: on
           | access tech: lte
           | signal quality: 40% (recent)
  --------------------------------
  Modes | supported: allowed: 2g, 3g, 4g; preferred: none
           | current: allowed: 2g, 3g, 4g; preferred: none
  --------------------------------
  IP | supported: ipv4, ipv6, ipv4v6
  --------------------------------
  3GPP | imei: 014697000106770
           | operator id: 310410
           | operator name: AT&T
           | registration: home
  --------------------------------
  3GPP EPS | ue mode of operation: ps-2
  --------------------------------
  SIM | dbus path: /org/freedesktop/ModemManager1/SIM/0
ubuntu@ubuntu:~$

[Jon Watson (jwatson-kdp)]

Attached the modemmanager system log output.

[Alfonso Sanchez-Beato (alfonsosanchezbeato)]

@Jon, thanks for the logs. The modem is using the generic plugin, which does not have direct support for NCM. That implies that if you want NCM, probably a new plugin needs to be implemented.

It might be interesting though to see if the modem can use pppd to establish a connection. Could you please share journal for that case and check if connectivity works? Creating a connection can be done via NetworkManager, with a command like:

$ nmcli c add type gsm ifname ttyACM2 con-name <name> apn <operator_apn>

(see details on [1] - the doc applies to UC but most of it is valid for classic too).

Also, if in the end you do not care about NCM/MBIM, you could try the latter to check if that works out of the box for you. I have seen in the AT commands manual from Sierra that you can switch to MBIM mode with
AT+KUSBCOMP=2
(after that probably you will need to reset the modem)

To go back to NCM after your testing:
AT+KUSBCOMP=0

Some other questions I have:
1. Which version of Ubuntu and ModemManager are you testing with?
2. The docs have different instructions for Verizon and rest of carriers, which carrier is this for?

[1] https://core.docs.ubuntu.com/en/stacks/network/network-manager/docs/configure-cellular-connections

[Jon Watson (jwatson-kdp)]

@Alfonso -

We did try pppd mode and it did work, but we saw we lost about 300 kb/s of performance.

The modem is configured as MBIM out of the box, so we switch it to NCM mode already. I think we tried it in MBIM mode, but I'll double check with my team. As I communicated previously, the only reason we use NCM is that is the recommended configuration from Nimbelink who is our vendor. We asked Nimbelink about Modemmanager and they didn't know anything about it.

We are using Ubuntu 20.04 LTS currently and we are planning to switch to UC20 targeted at our custom platform which Canonical is enabling for us. Alex can probably explain the details better than I can as there is another vendor involved.

Currently we are using AT&T as our carrier.

[Tony Espy (awe)]

It's unclear to me whether this is actually a bug with the modem-manager snap or not.

If it is, please provide additional details:

- version/revision of the snap
- version of Ubuntu Core
- details of the underlying system
- use case, steps to reproduce