Nonswitched SDLC subarea connection

A nonswitched synchronous data link control (SDLC) link between two NCPs can be used to connect two VTAM® domains. In Figure 1, the SDLC connection between NCP1 and NCP2 is used to connect the two VTAM domains (VTAM1 and VTAM2). This connection can operate at whatever speed the communication controller and NCP are capable of supporting. Each end of the SDLC connection is defined in each NCP using NCP definition statements. The connection can be composed of multiple links in the same transmission group because it is a connection between NCPs. To activate the link, one of the following condition must occur:

If each VTAM controls its respective NCP (NCP1 and NCP2), each VTAM domain (VTAM1 and VTAM2) must activate its end of the connection.
If one VTAM controls both NCPs (NCP1 and NCP2), the RNAME operand must be coded on either the PCCU definition statement or the operator command that is used to activate NCP.

The GROUP and SDLCST definition statements indicate to the NCP the link characteristics that are to be used when the NCP is operating as the primary or secondary end of the link.

The LINE and PU definition statements in the NCP define the link and link station connection between the NCPs. The majority of the operands used to define this connection are associated with NCP. However, you can specify VTAM-only operands such as ISTATUS. For information about the operands that are VTAM-only and are applicable to this connection, see Connecting an NCP to VTAM.

The sample coding in Sample coding for SDLC primary and secondary links and link stations and Sample coding for an intermediate routing node link illustrates the NCP definitions used to define a high-speed connection (1.47 megabytes per second) between NCP1 and NCP2. A set of definitions is required in each NCP.