Two network interfaces created by MC7304

I have a MC7304.
I use gobi3000-serial, and gobi3000-net drivers to use it under Linux (kernel 4.9)
And I get two network interfaces (eth3 and eth4 in my case).
It is working well on eth3 (internet access is OK)
My question is, what is the purpose of this second interface ??




The unit creates two /dev/qcqmi and two eth interfaces for two PDN’s which it is capable of creating (in theory the chipset can do 3 but there are limitations around this third one). Note you can only start stop multiple PDN’s when using the QMI SDK and not when using AT commands (i.e. at!scact=1,1).