I don’t see problem to have the DHCP on USB ECM port:
[8864798.502432] usb 3-6: Product: Sierra Wireless WP7607-1
[8864798.502438] usb 3-6: Manufacturer: Sierra Wireless, Incorporated
[8864798.502444] usb 3-6: SerialNumber: V284257032101004
[8864798.509630] GobiSerial 3-6:1.0: GobiSerial converter detected
[8864798.510011] usb 3-6: GobiSerial converter now attached to ttyUSB0
[8864798.510739] GobiSerial 3-6:1.2: GobiSerial converter detected
[8864798.510986] usb 3-6: GobiSerial converter now attached to ttyUSB1
[8864798.512679] GobiSerial 3-6:1.3: GobiSerial converter detected
[8864798.512988] usb 3-6: GobiSerial converter now attached to ttyUSB2
[8864798.513801] QMAP Disabled
[8864798.515434] GobiNet 3-6:1.8 eth1: register ‘GobiNet’ at usb-0000:00:14.0-6, GobiNet Ethernet Device, 5e:e4:09:45:f5:59
[8864798.515814] USB Speed : USB 2.0
[8864798.520669] cdc_ether 3-6:1.19 usb0: register ‘cdc_ether’ at usb-0000:00:14.0-6, CDC Ethernet Device, 22:c7:9a:99:c2:99
[8864818.495453] creating qcqmi0
[8864818.495738] RawIP mode
owner@CNHKG-EX-001367:~/Yocto/WP76/R13.3/yocto$ ifconfig usb0
usb0 Link encap:Ethernet HWaddr 22:c7:9a:99:c2:99
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
owner@CNHKG-EX-001367:~/Yocto/WP76/R13.3/yocto$ sudo dhclient usb0
[sudo] password for owner:
owner@CNHKG-EX-001367:~/Yocto/WP76/R13.3/yocto$ ifconfig usb0
usb0 Link encap:Ethernet HWaddr 22:c7:9a:99:c2:99
inet addr:192.168.2.3 Bcast:192.168.2.255 Mask:255.255.255.0
inet6 addr: fe80::20c7:9aff:fe99:c299/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:15 errors:0 dropped:0 overruns:0 frame:0
TX packets:27 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1632 (1.6 KB) TX bytes:7109 (7.1 KB)
owner@CNHKG-EX-001367:~/Yocto/WP76/R13.3/yocto$ ping 192.168.2.2
PING 192.168.2.2 (192.168.2.2) 56(84) bytes of data.
64 bytes from 192.168.2.2: icmp_seq=1 ttl=64 time=2.29 ms
64 bytes from 192.168.2.2: icmp_seq=2 ttl=64 time=2.16 ms