Visara LINCS Features - Manual (Page 50)

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LINCS Features
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DLUR
DLUR Host Circuits provide APPN routing services to dependent LUs associated with PUs
internal to the LINCS node. To configure a DLUR Host Circuit, enable APPN. Refer to the
sections titled APPN and DLUR for more details.
LLC
LLC Host Circuits are supported on Ethernet, Token Ring, or Frame Relay lines. To configure
an LLC Host Circuit, enable LLC on an Ethernet or Token Ring, or Frame Relay Line Options
panel and define an LLC Link Profile (Note that if you define a Frame Relay line, then LLC is
enabled by default).
SDLC
SDLC Host Circuits are supported on HSC and SCC Lines. To configure an SDLC Host
Circuit, set the Line Protocol to SDLC on a Line Options panel, and define an SDLC Link
Profile.
LINCS uses Synchronous Data Link Control (SDLC) to carry SNA data. Acting in the standard
role of SDLC secondary, LINCS can simultaneously handle PU2.0 and PU2.1 SNA traffic for
internal PUs, downstream PUs, and APPN. When configured for SDLC/DAP (Distribution
Access Point) and using an HSC board, LINCS can act as SDLC primary. As the primary
SDLC link station LINCS simulates the SDLC polling function of a FEP, polling other SDLC
controllers, such as SDLC DSPUs or adjacent APPN nodes. Both link roles can be full or half
duplex, and support single- or multi-drop configurations. Group Polling is also supported in
both roles (except SDLC/DAP on the SCC board). Both NRZ and NRZI signaling schemes
are supported, as well as permanent and controlled RTS modem handshaking.
Group Poll
The group poll feature allows the host to poll all PUs supported by the LINCS node via an
SDLC group address, instead of polling each address individually. Group poll allows customers
to configure the host to send a group poll to the LINCS node. LINCS will respond with data
from any one of the configured internal PUs, Token Ring DSPU, Ethernet DSPU, or SDLC-
attached DSPU (supported by the SDLC/DAP feature), that has inbound data pending. This
feature significantly improves communication line throughput and end-user response time by
reducing overall polling from the host and eliminating unproductive polls. Group poll is useful
in a gateway or when LINCS is supporting multiple PUs.
For situations which require more than 254 LUs, LINCS supports multiple PUs (up to 16).
This multiple PU support is useful in multi-domain environments where multiple hosts are
interconnected via the FEP. In this case, each host system could have its own PU in the
LINCS node.
Note: SDLC group poll functions only in half-duplex mode.
SNA
Systems Network Architecture (SNA) is a communications protocol that enables synchronous
transmission of data between logical units (LUs) that transmit or receive data. An LU is a
logical entity associated with an end-user, for example, a terminal connected to a LINCS node
or a host application program.