How does Gateway agent work?

Summary

Can someone please explain how the gateway agent work in the OMC architecture perspective

Content

With respect to Gateways, How does the Gateway agents High Availability work. Cloud agents are connecting to both of them based on load or does they work in like active / passive way in the sense that all targets connect to one of them and only if it fails, they fall over to the other Gateway agent. And to be in sync, do they keep transferring some data between the two of them ? I had a hard time finding more information about this in oracle documentation.