Connection between SAP Gateway and other SAP Systems

Hey folks,

I know that a SAP NetWeaver Gateway Server uses OData to talk to Devices in the internet.

But during making some investigations, i got a little confused: Does SAP Gateway use OData or RFC to get the data from other (SAP) Systems in the intranet?

I found this:

SAP Netweaver Gateway

I know it's now official SAP source, but is their chart right? I thought SAP Gateway uses OData to connect to other Systems in the intranet.

Or isn't that a question of either / or?

Thank you