Legacy Data System Reference - Comtech EF Data

Legacy Data
6.1 NetPerformer Support of SNA/SDLC
6.1.1 SDLC Driver
6.1.2 SNA/SDLC Ports
6.1.3 PUs
SDLC (Synchronous Data Link Control) is the link-layer protocol used in the SNA
architecture for low to medium-speed links. The SDLC discipline manages synchronous,
code-transparent, serial-by-bit information transfer between nodes that are joined by data
links.
The NetPerformer includes a full-featured SDLC driver:
• Comprehensive detection and recovery procedures for transmission errors.
• Local polling capabilities, where the NetPerformer generates and responds to
polls on behalf of the SDLC devices, and filters out administrative information
such as unnumbered and supervisory frames.
• The Group Poll feature offered in the IBM 3745 Front End Telecommunication
Processor.
• Support of point-to-point or multipoint, switched or non-switched port connections.
• Support of up to 64 SDLC controllers (PUs).
SNA/SDLC local polling enhances NetPerformer performance in the SDLC environment,
particularly for bulk data transfers between two hosts with peer-to-peer SNA PU type 4
definitions. The polling cycle is dramatically shortened by rapid spoofing of the SDLC
protocol, which increases the polling frequency of the FEP and improves the response
time. This permits high-speed LAN-to-LAN and FEP-to-FEP connections.
An SNA/SDLC port on the NetPerformer is any serial user port configured with an SDLC
protocol. Each SNA/SDLC port must be defined as either:
• A primary port (P-SDLC protocol), which connects to a cluster controller (PU),
or
• A secondary port (S-SDLC protocol), which connects to a front-end processor or
IBM mainframe.
The SNA/SDLC ports take input data from the PUs and send it over the composite link.
• Traffic priority is determined by the weight class to which the PU belongs; configure
it using the Class parameter.
• You can also define a filter to assign all SNA data to a particular class.
The NetPerformer is designed to handle up to 64 PUs (or controllers), which are
configured individually. Each active controller is logically attached to two interfaces, each
of which may be:
6-2 Memotec Inc.