IEEE Std 802.5c-1991 (Supplement to IEEE Std 802.5-1989 ) -Description
Abstract: Extensions to the 802.5 Token-Passing Ring standard are defined. These extensions implement a Dual Ring local area network (LAN) topology that provides full interoperability between stations conforming to 802.5, including coexistence on the same ring, and recovery from all single media failures with full capability restored. The Dual Ring topology and operation described are intended for applications that require very high availability and recovery from media and station failures.
Content
1. Overview
1.1 Introduction.
1.2 Definitions.
Abbreviations and Symbols.
2. Dual Ring Station Definition
3. Dual Ring Reconfiguration
4. Dual Ring Management Function
4.1 Dual Ring Management Function Inputs.
4.1.1 Break Indication.
4.1.2 MAC Insert Control Indication.
4.1.3 Active Monitor Present Indication.
4.1.4 Receive Beacon Reconfigure Indication .
4.1.5 Receive Beacon Normal Indication .
4.1.6 Transmit Beacon Reconfigure Indication .
4.1.7 Management Interlock Flag (MIF) Value .
4.1.8 Merge Permission Flag (MPF) Value.
4.2 Dual Ring Management Function Variables.
4.3 Dual Ring Management Function Timers.
4.4 Dual Ring Management Function Finite State Machine .
4.4.1 State D0: PASS.
4.4.2 State D1: NORMal.
4.4.3 State D2: TPWBNR.
4.4.4 State D3: RBPWRS .
4.4.5 State D4: TSWBNR.
4.4.6 State D5: WRAPB.
4.4.7 State D6: WRAPA .
4.4.8 State D7: ISOLated.
4.5 Dual Ring Management Function Outputs.
5. Management Interface
5.1 Station Management Interface .
5.1.1 Parameters
5.1.2 Events
6. IEEE Std 802.5 MAC Finite State Machine (FSM) Changes for Dual Ring Stations
6.1 MAC Inputs
6.1.1 MAC Break Flag.
6.1.2 MAC Transmit BNR Enable Flag.
6.2 Changes to the Standby Monitor FSM
6.2.1 Additional Standby Monitor State/Variable
6.2.2 New/Modified Standby Monitor FSM State Transitions.
