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LAT Architecture Specification V5.3.0
Company:
Digital Equipment Corporation
Part:
AA-NL26E-TE
Date:
1996-06
Keywords:
Copies
Address:
https://vt100.net/dec/aa-nl26e-te.pdf
Site:
VT100.net
Format:
PDF
Size:
648185 bytes (633 KiB)
Table of Contents
Chapter 1
Introduction
1.1
Scope
1.2
Associated Documentation
1.3
Conventions of the Specification
1.4
Conventions Used in this Specification
1.4.1
Names
1.4.2
Values
1.4.3
Protocol Message Encoding
1.4.4
Interfaces
1.5
Definitions
1.6
Assumptions and Requirements
1.6.1
Characteristics of the LAN Data Link
1.6.2
Characteristics of Nodes
1.7
Goals
1.8
Non-Goals
Chapter 2
Architecture Overview
2.1
Slot Layer
2.1.1
Connecting to the Host Service
2.1.2
Connecting to the Terminal Server Service
2.2
Virtual Circuit Layer
Chapter 3
Naming
3.1
Specification of Names
3.2
Specification of Text
3.3
Name Translation
3.3.1
Service Name Translation Process
3.3.2
Translation Process on a Source Node
3.3.3
Translation Process on a Destination Node
3.4
Local Area Directory Service
3.4.1
Multi-link Nodes
3.4.2
Multicast Addresses
3.4.3
Advertising Services with the Service Announcement Datagram
3.4.3.1
Building the Database on the Master
3.4.3.2
Duplicate Node Detection and Avoidance
3.4.3.2.1
Automatically Created Node Name
3.4.3.2.2
Loss of an Active ID ROM
3.4.3.2.3
Manually Created Node Names
3.4.3.2.4
Detecting Duplicate Nodes
3.4.3.2.4.1
Detecting Duplicate Nodes (pre LAT V5.3)
3.4.3.2.4.2
Detecting Duplicate Nodes (V5.3 or higher)
3.4.3.3
Error Recovery
3.4.4
Advertising through Solicit and Response Information Datagrams
3.4.4.1
Terminal Server Advertising Using Solicit Information
3.4.5
A Node Operating in Slave Mode
3.4.6
A Node Operating in Master Mode
3.4.7
Using an Agent for Solicitation
3.4.8
Solicit Information Transmission Policy
3.4.9
Response Information Transmission Policy
3.5
Access Control
3.6
LAN Data Link Path Management
Chapter 4
Circuit and Session Layers
4.1
Layer Interfaces
4.1.1
Types of Data Service
4.1.2
Slot Layer Client Interface
4.1.2.1
Summary of Functions
4.1.2.2
Description of Functions
4.1.3
Virtual Circuit Layer Client Interface
4.1.3.1
Summary of Functions
4.1.3.2
Description of Functions
4.1.4
Virtual Circuit Service Interface
4.2
Architectural Model
4.2.1
Virtual Circuit Service
4.2.1.1
Virtual Circuit State
4.2.1.2
Architecturally-Controlled Names and Variables
4.2.1.2.1
Virtual Circuit State Variables
4.2.1.2.2
Slot State Variables
4.2.1.2.3
Error Handling (Illegal Slots and Messages)
4.2.1.3
Virtual Circuit Message Types
4.2.1.4
Virtual Circuit State Transitions
4.2.1.5
Response Requested Flag and Balanced Mode
4.2.1.6
Message Mapping onto State Diagram
4.2.1.6.1
Master Virtual Circuit State Table
4.2.1.6.2
Slave Virtual Circuit State Table
4.2.2
User Connection Management and Data Flow
4.2.2.1
Service Classes
4.2.2.2
Slave Session Management
4.2.2.3
Multiplexing Over a Virtual Circuit
4.2.2.4
Slot Ordering Within Messages
4.2.2.5
Slot State Variables
4.2.2.6
Master Slot Mapping onto State Diagram
4.2.2.7
Master Slot Table
4.2.2.8
Slave Slot Mapping onto State Diagram
4.2.2.9
Slave Slot State Table
4.3
Algorithms
4.3.1
Virtual Circuit Layer
4.3.1.1
Message Buffer Flow Control
4.3.1.2
Circuit Starter (Master Only)
4.3.1.3
Data Volunteered
4.3.1.4
Credits To Be Returned
4.3.1.5
Circuit Ender
4.3.1.6
Message Receiver
4.3.1.7
Message Transmitter
4.3.1.7.1
Transmitter Functions
4.3.1.7.2
Path Management
4.3.1.8
General Timer Policy
4.3.1.9
Keep-alive Process
4.3.1.10
Progress Process
4.3.1.11
Delayed Acknowledgments
4.3.1.11.1
Delayed Acknowledgment Implementation Suggestions
4.3.2
Slot Layer
4.3.2.1
Session Starter (Master)
4.3.2.2
Session Starter (Slave)
4.3.2.3
Slot Demultiplexer
4.3.2.4
Slot Multiplexer
4.3.2.5
Session Ender
4.3.2.6
Slot Flow Control
Chapter 5
Connection Solicitation
5.1
Architectural Model
5.1.1
Service Sharing
5.1.1.1
Queue Coordination
5.1.1.2
Queue Access
5.1.1.3
Queue Structure
5.1.1.4
Queue Operations
5.1.1.4.1
Connection Solicitation Operations
5.1.1.4.2
Status Solicitation Operations
5.1.1.5
Concatenating the Status Entries
5.1.1.6
Retransmission and Time-out Policies
5.1.2
Connection Initiation
5.1.2.1
Solicitation Process Message Flow
5.1.2.1.1
Initiation
5.1.2.1.2
Queuing
5.1.2.1.3
Rejection
5.1.2.1.4
Acceptance
5.1.2.1.5
Resolicitation
5.1.2.2
Solicitation Process State Tables
5.1.2.3
Name and Information Field Presentation
Chapter 6
LAT Management
6.1
Data Types
6.2
LAT Entity
6.2.1
Identifier Attribute
6.2.2
Directives
6.2.2.1
Create Directive
6.2.2.2
Delete Directive
6.2.2.3
Enable Directive
6.2.2.4
Disable Directive
6.2.3
Characteristic Attributes
6.2.4
Status Attributes
6.2.5
Counter Attributes
6.2.6
Events
6.3
Port Entity
6.3.1
Identifier Attribute
6.3.2
Directives
6.3.2.1
Delete Directive
6.3.3
Characteristic Attributes
6.3.4
Status Attributes
6.3.5
Counter Attributes
6.3.6
Events
6.4
Named Port Entity
6.4.1
Identifier Attribute
6.4.2
Directives
6.4.2.1
Create Directive
6.4.2.2
Delete Directive
6.4.2.3
Enable Directive
6.4.2.4
Disable Directive
6.4.3
Characteristic Attributes
6.4.4
Status Attributes
6.4.5
Counter Attributes
6.4.6
Events
6.4.6.1
Illegal Password
6.5
(Named Port) Queued Request Entity
6.5.1
Directives
6.5.1.1
Delete Directive
6.5.2
Identifier Attributes
6.5.3
Characteristic Attributes
6.5.4
Status Attributes
6.5.5
Counter Attributes
6.5.6
Events
6.6
Service Profile Entity
6.6.1
Identifier Attribute
6.6.2
Directives
6.6.2.1
Create Directive
6.6.2.2
Delete Directive
6.6.2.3
Enable Directive
6.6.2.4
Disable Directive
6.6.3
Characteristic Attributes
6.6.4
Status Attributes
6.6.5
Counter Attributes
6.6.6
Events
6.7
Local Service Entity
6.7.1
Identifier Attribute
6.7.2
Directives
6.7.2.1
Delete Directive
6.7.3
Characteristic Attributes
6.7.4
Status Attributes
6.7.5
Counter Attributes
6.7.6
Events
6.7.6.1
Illegal Password
6.8
(Local Service) Queued Request Entity
6.8.1
Directives
6.8.1.1
Delete Directive
6.8.2
Identifier Attributes
6.8.3
Characteristic Attributes
6.8.4
Status Attributes
6.8.5
Counter Attributes
6.8.6
Events
6.9
Destination Node Subentity
6.9.1
Identifier Attribute
6.9.2
Directives
6.9.2.1
Delete Directive
6.9.3
Characteristic Attributes
6.9.4
Status Attributes
6.9.5
Counter Attributes
6.9.6
Events
6.10
Path
6.10.1
Identifier Attribute
6.10.2
Directives
6.10.2.1
Delete Directive
6.10.3
Characteristic Attributes
6.10.4
Status Attributes
6.10.5
Counter Attributes
6.10.6
Events
6.10.6.1
Illegal Message
6.10.6.2
Illegal Slot
6.10.6.3
Illegal Datagram
6.11
Circuit Entity
6.11.1
Identifier Attribute
6.11.2
Directives
6.11.2.1
Delete Directive
6.11.3
Characteristic Attributes
6.11.4
Status Attributes
6.11.5
Counters
6.11.6
Events
6.12
Service Entity
6.12.1
Identifier Attributes
6.12.2
Directives
6.12.2.1
Delete Directive
6.12.3
Characteristic Attributes
6.12.4
Status Attributes
6.12.5
Counter Attributes
6.12.6
Events
6.13
Link
6.13.1
Identifier Attributes
6.13.2
Directives
6.13.2.1
Create Directive
6.13.2.2
Delete Directive
6.13.2.3
Enable Directive
6.13.2.4
Disable Directive
6.13.3
Characteristic Attributes
6.13.4
Status Attributes
6.13.5
Counter Attributes
6.13.6
Events
Appendix A
Service Class 1 – Interactive and Application Terminals
A.1
Service Class 1 Slot Format Extensions
A.1.1
Start Slot Status Field
A.1.2
Attention Slot Status Field
A.1.3
Data_b Slot Extension
A.1.3.1
Information Exchange Using Data_b Slots
A.1.3.2
Guidelines and Recommendations for Data_b Slot Processing
A.1.3.2.1
Port Characteristics
A.1.3.2.2
Session Management
A.1.3.2.3
Data Errors
A.1.3.2.4
Data_b Slot Processing
A.1.3.2.5
Implementation Examples
A.1.4
Passwords
A.1.5
Protocol Loopback Tests
Appendix B
Message Formats
B.1
Bit and Byte Ordering
B.2
Use of the Message Type Field
B.3
Maximum Protocol Message Sizes
B.4
Slot Headers and Extensions
B.5
Virtual Circuit Messages
B.5.1
Start Message
B.5.2
Run Message
B.5.2.1
Common Slot Formats
B.5.2.1.1
Start Slot
B.5.2.1.2
Data_a Slot
B.5.2.1.3
Data_b Slot
B.5.2.1.4
Attention Slot
B.5.2.1.5
Reject Slot
B.5.2.1.6
Stop Slot
B.5.2.1.7
Slot Reason Codes
B.5.2.2
Service Class 1 Slot Formats
B.5.2.2.1
Start Slot
B.5.2.2.2
Attention Slot Format
B.5.2.2.3
Data_b Slot
B.5.3
Stop Message
B.6
Connection Solicitation Messages
B.6.1
Command Message
B.6.2
Status Message
B.7
Directory Service Messages
B.7.1
Service Announcement
B.7.2
Solicit Information Message
B.7.3
Response Information Message
Appendix C
Miscellaneous Algorithms
C.1
Protocol Versions and ECO Control
C.1.1
Protocol Version Negotiation
C.1.1.1
Virtual Circuit Messages
C.1.1.2
Non-Virtual Circuit Messages
C.1.1.3
Service Announcement Message
C.1.1.4
Subsequent Message Validation
C.2
Generating Identifiers
C.2.1
Interface to the Algorithm
C.2.2
Data Structures
C.2.3
Algorithm Operation
C.2.4
Alternate Algorithms
C.3
Random Numbers
Appendix D
Architectural Constants
Appendix E
Management
E.1
Parameters
E.2
Counters
E.2.1
Slave Node Management
E.2.1.1
Initialization
E.2.1.2
Slave Group Codes
E.2.1.3
Slave Node Name and Service Names
E.2.1.4
System Shutdown
E.2.2
Master Node Management
E.2.2.1
Initialization
Appendix F
Compatibility and Implementation
F.1
Product Considerations
F.1.1
Host
F.1.2
Terminal Server
F.2
Buffering
F.2.1
Virtual Circuits
F.2.2
Slots
F.2.3
Implementation Subsets of the LAT Architecture
F.2.4
Local Data Base
F.2.5
Cluster Static Load Balancing
F.2.6
Multiprocessors, Gateways, and Virtual Machines
F.3
LAT V5.1 and V5.0 Compatibility Issues
F.3.1
Virtual Circuit Establishment
F.3.1.1
Multiple Virtual Circuits
F.3.2
Data_b Slot Length Compatibility
F.3.3
Data_b Slot Data Compatibility
F.3.4
Data_b Slot Compatibility for Speed
F.3.5
Non-unique Node Names
F.3.6
Implementation of the Ethernet and 802 Protocols
F.4
LAT V5.2 and V5.1 Compatibility Issues
F.4.1
Attention Slots, MBZ Checking
F.4.2
Minimum LAT V5.2 Implementation
F.5
LAT V5.3 Compatibility Isseus with LAT V5.X
F.5.1
Minimum LAT V5.3 Implementation
Appendix G
Revision History
G.1
Version 5.0
G.2
Version 5.1
G.3
Version 5.2
G.4
Version 5.3