RFC Destination Query

Hi Experts,

I have a query on RFC destination.

We create RFC destination for connecting between ABAP system and XI system.

Say for example we create ABAPRFC and XIRFC. Now if for some reason say ABAPRFC stops working then will IDOC/Proxy be sent to XI system as XIRFC is working. Also if XIRFC stops working and ABAPRFC is working then can we send IDOC/Proxy to ECC system. Or we need both of them to work for sending data to either of the systems.

Regards,

Shaibayan