This Figure shows how multiple instances of this core should be connected in a design so that clock resources can be saved using the shared logic feature.
Both the core instances are configured for the GMII TX clock to be sourced internally. For example, GMII_TO_RGMII_0, shared logic is in the core and for IP instance GMII_to_RGMII_1, shared logic is in the example design (which means the IP block level does not have any shared clock/reset resources). Instance GMII_TO_RGMII_0 generates all the required clocks, namely ref_clk and the GMII TX clock. These clocks are used by the instance GMII_TO_RGMII_0 internally and also shared with instance GMII_TO_RGMII_1.