1. 802.17c Protected Inter-Ring Connection Rafi Ram - Corrigent Systems May 2007

2. 2 PIRC Sublayer in MAC Block Diagram

3. 3 PIRC Suggestion Highlights Stations A & B are members of a protection group (PG) for interconnect between two rings Station A and station B are protection group members (PGM) One of the stations in a PG is provisioned as the “0” member, and the other as the “1” member One of the interconnected rings shall be provisioned as the “primary” ring and the other as “secondary” ring

4. 4 Network Diagram Stations A & B are protection group members on the primary ring Station A is the “0” member and station B is the “1” member Stations C & D are protection group members on the secondary ring Station C is the “0” member and station D is the “1” member Stations A & C are “peer” stations Stations B & D are “peer” stations Stations A & B are “mate” stations Stations C & D are “mate” stations

5. 5 PGM State Machine Self-OK : The communication with the peer station is OK (and no “admin-down”) Mate-OK : The protection group stations are visible in the topology of both the primary and secondary rings, and the mate station advertises status “self-OK” The 802.17c specification should not include a mandatory method for determining the value of the “hold-off” timer

6. 6 myFlow(frame) Function The function could be used to implementation of the load-balancing functionality On of the possible implementations of the myFlow function could be : myFlow(frame) = (hashing(frame) modulo 2) == member-type “member-type” equals to 0 if the station is the 0 member, and equals to 1 if the station is the 1 member

7. 7 PIRC Sublayer Logic on the Path Client  MAC as State Table RowConditionAction 1MAC is on primary ringForward 2PG state is “fwd-none”Discard 3PG state is “fwd-all”Forward 4(myFlow(frame)Forward 5-Discard

8. 8 PIRC Sublayer Logic on the Path Client  MAC as Pseudo-Code if (MAC is on primary ring) forward frame else if (((PG state is “fwd-mine”) and myFlow(frame) ) or (PG state is “fwd-all”)) then forward frame else discard frame

9. 9 PIRC Sublayer Logic on the Path MAC  Client as State Table RowConditionAction 1(MAC is on primary ring) and (RPR SA is the mate MAC address) and (PG state is “fwd-all”) Discard 2MAC is on primary ringForward 3RPR SA is the mate MAC addressDiscard 4PG state is “fwd-none”Discard 5PG state is “fwd-all”Forward 6myFlow(frame)Forward 7-Discard

10. 10 PIRC Sublayer Logic on the Path MAC  Client as Pseudo-Code if (MAC is on primary ring) if ((PG state is “fwd-all”) and (RPR SA is the mate MAC address)) discard frame else forward frame else if (RPR SA is the mate MAC address) discard frame else if (((PG state is “fwd-mine”) and myFlow(frame)) or (PG state is “fwd-all”)) then forward frame else discard frame