EG25-G IP Passthrough (IPPT)

IoT Modules LTE Standard Module
1

I aim to create an LTE Modem, similar to the Netgear LM1200, which utilizes the EC25-AF module,

as confirmed by the FCC: LM1200 - Internal Photos.

The modem would bridge the Ethernet connection from the module directly to a RJ45 Ethernet port.

It appears the EC25-AF and EG25-G modules use the same AT commands.

The AT Command Manual for the EG25-G also references the EC2x family. However, the -AF variant isn’t explicitly mentioned.

If both modules support the same AT commands, it should be possible to achieve the same with the EG25-G right?

I use OpenWRT and QMI works without problems, but AFAIK QMI can’t be used to implement a Modem, because no Layer2 packet (no MAC) is used.

Switching to ECM using AT+QCFG="usbnet",1 assigns OpenWRT’s DHCP client a private IP address from the EG25-G. In this mode, the module enables NAT, which prevents it from functioning as a true modem.

How can I disable NAT in ECM mode to enable IPPT?

Or am I missing something and it is possible to use QMI to create a modem?

AT

AT+QGMR:

EG25GGCR07A02M1G_30.200.30.200
OK

The Firmware 30.200.30.200 is apparently not the newest. Firmware for EG25GGCR07A02M1G_30.201.30.201

ATI:

Quectel
EG25
Revision: EG25GGCR07A02M1G
OK

AT+QMAP=?:

+QMAP:"LANIP" <LAN_IP_start_address>,<LAN_IP_end_address>,<GW_IP_address>,<effect>
OK
2

Please check

AT+QIPPTCFG=?

If it is not supported, I am afraid it do not suppport IPPT for the firmware version you tried.
Normally Quectel would not develop the IPPT for EG25 because it support RMENT and MBIM already.

3

It seems MBIM provides an IP packet over USB, as suggested by the ModemManager - The MBIM standard documentation entry.

In my understanding I need a Layer 2 packet with a MAC address to be able to bridge with another port.

I have not found much information about RMENT so far, but it seems to be related to QMI so my fear is it also only provides IP packets.

Maybe my understanding of IPPT is wrong, because I don’t understand how RMENT and MBIM can be an alternative to IPPT.

I thought with IPPT, ethernet frames are used, because it runs in ECM mode and therefore I can implement a modem with a simple bridge.

What is the recommended way to implement a basic modem with Quectel modules?

AT+QIPPTCFG=?:

ERROR
4

In RMNET and MBIM mode, the network packet will not over the AP side ot the EG25G.
But in ECM mode, actually there is a DHCP service in the AP side of the EG25G that assign the USB host the IP address.

5

Alright thanks for the information, this confirms my assumption. Still new to this, and haven’t had much time to try every thing out by myself.
So only in ECM Ethernet packets are used because of the DHCP server, which I actually try to avoid.

I though I could simply bridge the ports together but without Ethernet packets this is not possible I guess.

How can I implement an LTE modem with Quectel modules? I’m a bit lost on this one.

6

If you can use e-service to submit an order, you can apply for a firmware version that supports IPPT with ECM.

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7

In rmnet and MBIM mode, the usbnet interface for host is in RAW IP mode.

8

Thanks for the table.
I haven’t purchased the module directly from Quectel, am I still able to obtain the firmware?

It would be very helpful, as otherwise, the only idea I have is to write a kernel module that wraps QMI’s IP frames into Ethernet frames. However, I’m not even sure if this is actually feasible.

9

Please check the EG25GGCR07A02M1G_30.203.30.203. But it will also do not support the IPPT with ECM.

10

Thanks for the new firmware version, but I’m not sure why upgrading to this version would be helpful if IPPT is still not supported?

Am I correct in assuming that a LTE Modem should be implemented using ECM+IPPT, or am I on the wrong track?
It seems strange that such basic functionality is so difficult to access, but since I’m new to this, there might be a reason I’m not aware of.

11

Please read the ReleaseNote in the new firmware.
As mentioned, ECM mode is not the recommended mode for EG25G.
Normally the customer would like to try RMNET/QMI.

12

The thing is, I want to implement a so-called Modem.
I probably don’t need to explain what a modem is, since the Quectel module itself implements one, but I feel this idea might be getting lost in translation.

In general terms, a modem is a device that connects your home network to your ISP. It translates signals from your ISP into a format your devices can use to access the internet, and vice versa. Typically, only one device can connect directly to the modem.
Usually, a router is connected to the modem. The router uses the modem connection as the WAN interface and runs a DHCP client on that interface.

Now, back to the problem.

What is the recommended way to implement a Modem in RMNET/QMI mode when only IP packets are delivered?

13

As I provided in the piture, Quectel would provide the quectel-CM for the customer to set up datacall.
Please try it. Once it has started the rmnet data call then the wwan0 also support the DHCP.

14

Are you intentionally avoiding my question, or am I misunderstanding something?

What is the purpose of using RMNET when it only provides IP packets, which cannot be used with a MAC switch?
Or does the MBIM Frame contain an Ethernet Frame?

Also, did you understand what I’m trying to build? You didn’t respond to that, and I feel like my goal might not be clear.

Additionally, I would like to avoid using the non OpenSource Quectel-CM. I’m not sure if this is the official repository I found, but it contains a README that falsely claims it is Open Source, while it actually uses a custom license that discriminates against non-Quectel customers.

15

quectel-CM is opensource. You can see all the code.
MBIM also do not contain the Ethernet frame.

16

quectel-CM is opensource. You can see all the code.

Read the Open Source Definition. Only because you can see the code it is not Open Source, in your logic Unreal Engine is also Open Source.

Asking again:

What is the purpose of using RMNET when it only provides IP packets, which cannot be used with a MAC switch?

17

Sorry, we have no plan to provide IPPT+ECM functions for individual developers. If you must use EG25G and need IPPT+ECM, please contact our sales and request IPPT+ECM.
Otherwise maybe you can try the Quectel 5G module.

18

In fact, the packets sent and received from the operator should not have MAC. This is not an Ethernet or WiFi network. In fact, if you insist on using ECM, it will bring more consumption. The speed and performance of ECM are much worse than RMNET.