Description: This table contains configuration information that is used to manage the SDLC interface. Each row in the table defines either an upper or lower SAP (service access point). SAPs permit SDLC to communicate with layers above (always SNALC) and below it in the protocol stack.

The maximum number of rows in the table is limited by sdlcSapNumber, which is an integer in the range 1 to 8. Since SDLC upper and lower SAPs have a one-to-one relationship, this makes 4 upper and 4 lower SAPs available. Each pair control one physical SLDC link (via the BOP).

The SLDC interface has two modes of operation: TIU (terminal interface unit) and HIU (host interface unit).

- TIU mode is used when the SDLC SAP is connected to one or more SNA control units (secondary link stations) and their supported terminals. It emulates a primary link station.

- HIU mode is used when the SLDC SAP is connected to a host. It communicates across a WAN link with the TIU, and locally with the host via SDLC. In communications with the host it emulates the control units (secondary link stations) connected to the TIU.

The SDLC interface supports connections with a maximum of 64 link stations. These can be distributed in any combination across the supported physical links.