Dear Sir,
The Zynq OS is a bare metal command interpreter. The command are indeed received from the Ethernet peripheral in the processing system.
star_lib\sip_zc706_host_if\EDK\zc706\sw\zc702_host_if in the firmware source code contain the software, most of the job done in sip.c. This software is a modified LWIP reference software.
Best Regards,
Arnaud