SCCM 1610 introduces changes how boundary groups work. The main differences are following:
1.There is a new term relationships, these are boundary group relations between them.
2. If a SCCM client is in boundary group, then now it is called its current boundary group.
3.Neighbor relationships can be defined between boundary groups. Neighbor relationships define period in minutes when client can fallback to next boundary group.
4. Boundary groups are converted to new model when SCCM is upgraded to version 1610.
So lets have an example. Client is in boundary group 1 (its current boundary group) that has 30 minute neighbor relationship with boundary group 2. Each boundary group has one distribution point associated to it.