osmo-gbproxy is a proxy for the Gb interface within the 3GPP GERAN (GPRS/EDGE RAN) architecture. It is part of the Osmocom Open Source Mobile Communications projects.
It allows you to aggregate many Gb links/connections into one. It also has the ability to convert between different Gb interface protocol stacking, such as from Gb-over-FrameRelay to Gb-over-IP.
Until 2021 it used to be part of the osmo-sgsn git repository, and before that (until 2017) part of openbsc.git
Homepage and Issue Tracker
You can find the user manual at https://ftp.osmocom.org/docs/latest/osmogbproxy-usermanual.pdf and the VTY reference manual at https://ftp.osmocom.org/docs/latest/osmogbproxy-vty-reference.pdf.