LAN Bridge 100 Technical Manual

This document is the Technical Manual for the Digital Equipment Corporation LAN Bridge 100, identified by order number EK-DEBET-TM-003. It is a comprehensive reference designed for training, field service, and manufacturing personnel with prior experience in Ethernet networks.

The manual provides technical information on the LAN Bridge 100 network bridge, covering its hardware logic, diagnostic firmware and software, and general operating procedures.

Key aspects covered in the document include:

• Introduction: An overview of the LAN Bridge 100 unit, including its role in extending Ethernet and IEEE 802.3 networks, its transparent operation, functional description (packet filtering, address learning, protocol independence, automatic backup/loop detection), product versions (local and remote with fiber-optic options), packaging, controls, status LEDs, and connectors. It also details optional features like the LAN Traffic Monitor (LTM) and Remote Bridge Management Software (RBMS) for network analysis and management.
• Installation and Verification: Step-by-step instructions for unpacking, selecting voltage, configuring switches, rack-mount and wall-mount installation, and connecting transceiver and fiber-optic cables. It also provides procedures for verifying the installation through LED status checks and network communication.
• Operation: A detailed explanation of the bridge's six operational states (SELF-TEST, BROKEN, INITIALIZATION, PREFORWARDING, FORWARDING, and BACKUP). It describes packet memory data structures, the learning and forwarding process (including address table management, binary search, and handling special cases like stale packets and address aging), and the critical loop detection mechanism based on the spanning tree algorithm. Foreground and background operations, Maintenance Operation Protocol (MOP), and self-test routines are also covered.
• Technical Description: Block-level functional descriptions of the LAN Bridge 100 hardware circuits, breaking down the system into its core subsystems: Network Interconnect (NI), Table Lookup (TLU), Processor, and Power Supply. It details components like LANCE chips, SIA, various memory types (ROM, RAM, NVRAM), timers, reset circuitry, and comparators.
• Maintenance: Procedures for maintaining the LAN Bridge 100, focusing on corrective maintenance. This includes troubleshooting tips, fault diagnosis flowcharts, replacement procedures, and detailed instructions for disassembling the bridge components (plastic enclosure, chassis cover, fiber-optic interface, power supply, and logic module).
• Fiber-Optic Link Analysis (Appendix B): A dedicated section on fiber-optic systems, discussing coupling considerations, typical cable attenuation values, guidelines for connectors and splices, and methods for attenuation measurement and system certification. It also provides information on attenuator installation.

In essence, this manual provides all necessary information for technical personnel to understand, deploy, and maintain the Digital LAN Bridge 100 within an Ethernet network environment.