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802.17c Protected Inter-Ring Connection

802.17c Protected Inter-Ring Connection. Rafi Ram - Corrigent Systems July 2007. 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)

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802.17c Protected Inter-Ring Connection

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  1. 802.17cProtected Inter-Ring Connection Rafi Ram - Corrigent Systems July 2007

  2. 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 interconnected rings shall be provisioned as the “primary” ring and the other as “secondary” ring • The station on the secondary ring with the lower MAC address is designated as the “0” member, and the other as the “1” member

  3. Network Diagram • Stations A & C are “peer” stations • Stations B & D are “peer” stations • Stations A & B are “mate” stations • Stations C & D are “mate” stations • 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

  4. Station-OK State Variable Station-OK = (adminStatus==UP) AND (mateVisable==TRUE) AND

  5. Peer Stations Communication • Peer stations exchange messages which are also used as “keep-alive” • The messages consist the following information (per protection group): • Station-OK state variable • Peer keep-alive timer expired • The peer messages are sent : • periodically • after a protection event • after change of admin-status • after peer keep-alive timer expires

  6. Self-OK State Variable Self-OK = (my_Station-OK==TRUE) AND (my_KA_Timer_Expired==FALSE) AND (peer_Station-OK==TRUE) AND (peer_KA_Timer_Expired==FALSE)

  7. Mate Stations Communication • Mate stations exchange messages which are also used as “keep-alive” • Mate stations exchange the value of the Self-OK state variable (per protection group) : • The mate messages are sent : • periodically • after a protection event • after change Self-OK state variable value • The messages could be new control type or new OAM type

  8. PIRC Stations Communication

  9. Mate-OK State Variable Mate-OK = (mateVisable==TRUE) AND(mate_Self-OK==TRUE) AND (mate_KA_Timer_Expired==FALSE)

  10. PGM State Machine

  11. MAC Table Flush • 802.17b – When an interconnecting station no longer appears in the topology, the MAC entries associated with that stations are deleted • When a PIRC station it sends SAS_Group_Notify message when : • it changes PG state to “FWD-None” • it changes PG state from “FWD-All” to “FWD-mine”

  12. 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 • The hashing could be on the service class and/or VLAN • “member-type” equals to 0 if the station is the 0 member, and equals to 1 if the station is the 1 member

  13. PIRC Sublayer Logic on the Path Client MAC as State Table

  14. 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

  15. PIRC Sublayer Logic on the Path MAC  Client as State Table

  16. 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

  17. Local Tributaries at PIRC Stations • According to the suggested algorithm, if the PIRC station are isolated on the primary ring, then their local tributaries are also disconnected • Complicating the algorithm to allow forwarding through the secondary ring is not critical because : • isolation on the primary ring is a DUAL failure • if the primary ring has isolation, the local tributaries at the PIRC stations are usually not the biggest problem

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