SSCP-SSCP sessions provide control and coordinate session setup for cross-domain and cross-network sessions. These sessions are established between VTAMs only. SSCPs exchange capabilities during CDRM activation. SSCP-SSCP sessions are established between all hosts in a network. SSCP-SSCP sessions can be established only between two hosts with subarea function. Within one subarea network, for an LU-LU session to be established, the SSCPs that own the LUs must be in session with one another.

For dependent LUs, the SSCPs must also establish SSCP-PU and SSCP-LU sessions before an LU-LU session can be established. An SSCP establishes sessions with PUs and LUs defined to it during network activation, or, in switched links, during link activation. SSCP-LU sessions need to be established for dependent LUs only. Independent LUs can function without an SSCP-LU session.