NI PortArch Nov83

This document, the LCG NI Port Architecture Specification (Revision 6.0, dated 10-NOV-83), details the software interface for controlling an LCG Network Interconnect (NI) port. Its primary goal is to specify the port's services and functionality to comply with various DEC corporate standards, including the Ethernet specification, NI Product Architecture, DNA NI Data Link, and Low Level Maintenance Operation (MOP). The document explicitly states it does not cover the physical channel, higher-level network issues, or network architectures beyond the data link Ethernet specification.

The LCG NI port functions as a multi-access serial interconnect for data packet exchange, providing Data Link and Physical Channel layers of the ISO OSI model and interfacing with the KL10 E/Cbus.

Key architectural elements and functionalities described include:

• Architecture Overview: Introduces port addresses, the Port Control Block (PCB), queue structures, multi-cast address tables, and packet filtering.
• Port Control Block (PCB): A central data structure in host memory that anchors all queues (Command, Response, Unknown Protocol Type Free) and tables, serving as the main control structure for the NI port.
• Queue Structures: Details the format and use of doubly-linked lists for commands, responses, and free queue entries, enabling communication between the port driver and the port.
• NI Packet Format: Specifies the basic structure of data frames on the NI wire, including destination/source addresses, protocol type, data, and frame check sequence.
• Received Packet Filtering: Explains how the port filters incoming datagrams based on destination address (physical, broadcast, multi-cast) and protocol type, using the Protocol Type Table (PTT) and Multi-cast Address Table (MCAT).
• Port Commands and Responses: Defines the communication packets exchanged between the driver and port, covering command processing and response generation for various events.
• Error Handling: Outlines the port's capabilities for retrying operations, managing fatal hardware errors, and reporting specific error events (e.g., excessive collisions, CRC errors, buffer issues).
• Event Counters: Provides a list of counters for performance monitoring and diagnostics, tracking various events like bytes/frames transmitted/received, collisions, and discarded datagrams.
• Port States: Describes the four operational states of the LCG NI port: Disabled, Initialize, Enabled, and Halted.
• Data Formatting Modes: Details two modes for mapping 8-bit NI bytes into 36-bit KL10 words: Industry Compatible Mode and High Density Mode.
• Command Specification: Provides detailed formats and functions for numerous commands, including SNDDG (Send Datagram), LDPTT (Load Protocol Type Table), LDMCAT (Load Multi-cast Address Table), RCCNT (Read and Clear Performance Counters), and commands for reading/writing port/link interface and NI station addresses.

The document also includes an opcode summary and programming notes on reset and initialization procedures.