ECS replication network segregation

ECS seems to use the work "replication" for two distinct meanings.

1) Inter-site data movement from one VDC to another VDC at a different site.  (WAN traffic)  

2) Intra-VDC movement of data slices/chunks between nodes and disks within one VDC for local data protection.  (local traffic).  

My understanding is that a "replication network" is for 1) above (aka geo-replication) , and that 2) above is on the "data network".  Is this correct?    The confusion arises from a "replication group" containing both local and remote nodes.

Thanks.