Sense code 087C

SSCP-PU session not active: A gateway SSCP-PU session that is needed to establish an address transform for the intended cross-network LU-LU session was not active, or the gateway node is not defined.

VTAM® Information: When VTAM receives this sense code for a session initiation, it continues searching through the adjacent SSCP table until the destination LU is found or routing is exhausted.

Bytes 2 and 3 contain sense-code-specific information that indicates the specific reason for not rerouting the request.
0000
No specific code applies.

VTAM hint: A possible cause of this error is that the SSCP-PU session is not active on the DLU side.

This sense code might not indicate an error. If the destination side cannot use the request network address assignment (RNAA) to obtain network addresses for communication across the network boundary, it will issue the 087C0000 sense code and the origin side will have to obtain the network addresses. So you might see this sense code but the session will set up successfully.

0001
An SSCP in the session setup path for an LU-LU session has lost connectivity with a gateway node traversed by the session, and has no other way to learn that the session has ended. An intermediate SSCP sends this sense data to one adjacent SSCP when it had previously lost connectivity with the other adjacent SSCP on the same session setup path. An endpoint SSCP sends this sense data to its adjacent SSCP when it had previously lost connectivity to a dependent LU or the boundary function of an independent LU.
0002
The SSCP lost connectivity with the boundary function of an independent PLU after the LU-LU session was started, and has no other way to learn that the session has ended; the SSCP either never had a session to a gateway node in the LU-LU session path, or had previously lost connectivity to it.
0003
The SSCP lost connectivity with the boundary function of an independent SLU after the LU-LU session was started, and has no other way to learn that the session has ended; the SSCP either never had a session to a gateway node in the LU-LU session path, or had previously lost connectivity to it.