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M2UA Peer-Peer Adaptation Layer SIGTRAN Working Group March 29, 2000

M2UA Peer-Peer Adaptation Layer SIGTRAN Working Group March 29, 2000. M2UA Peer-Peer Adaptation. Background First incorporated into M2UA draft-ietf-sigtran-m2ua-01 Case 1: M2UA Backhaul Case 2: M2UA Peer-Peer (“M2Peer”) Ram Dantu presentation, IETF-46 November 1999

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M2UA Peer-Peer Adaptation Layer SIGTRAN Working Group March 29, 2000

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  1. M2UA Peer-Peer Adaptation LayerSIGTRAN Working GroupMarch 29, 2000

  2. M2UA Peer-Peer Adaptation • Background • First incorporated into M2UA draft-ietf-sigtran-m2ua-01 • Case 1: M2UA Backhaul • Case 2: M2UA Peer-Peer (“M2Peer”) • Ram Dantu presentation, IETF-46 November 1999 • Drivers for M2UA Peer-Peer (Case 2) • Support MTP3 transport over SCTP (RFC 2719) • Seamless intermix of SS7 Links and IP Links • Maintain added MTP3 End-End Reliability Functions • Changeover / Changeback / MSU Retrieval • Link Alignment / Proving • Congestion Detection / Notification • SLS Loadsharing

  3. MTP2 M2UA M2UA MTP2 SCTP SCTP MTP1 IP IP MTP1 M2UA Case 1 (Backhaul) Architecture SS7 IP MGC SEP SG SS7 Appl SS7 Appl MTP2 Primitives Backhaul MTP3 MTP3 NIF IP Network SEP - SS7 Signaling Endpoint NIF - Nodal Interworking Function SG - Signaling Gateway SCTP - Simple Control Transmission Protcol

  4. MTP2 M2UA M2UA MTP2 SCTP SCTP MTP1 IP IP MTP1 M2UA Case 2 (Peer-Peer) Architecture SS7 IP MGC SEP SG SS7 Appl SS7 Appl MTP3 MTP3 MTP3 Peer-to-Peer Link Protocol IP Network SEP - SS7 Signaling Endpoint SG - Signaling Gateway SCTP - Simple Control Transmission Protcol

  5. Case 1: M2UA Backhaul Protocol Characteristics Asymmetric MGC Client – SG Server Protocol DataUnits Data Establish Request Establish Confirm Release Request Release Confirm Release Indication State Request State Confirm State Indication Data Retrieval Request Data Retrieval Confirm Data Retrieval Indication Data Retrieval Complete Indication Case 2: M2UA Peer-Peer Protocol Characteristics Symmetric SP Peer – SP Peer Protocol DataUnits Data Status - Out Of Alignment Status - Normal Alignment Status - Emergency Alignment Status - Out Of Service Status – Processor Outage Status – Busy Contrasting M2UA Case 1 and Case 2

  6. Case 1: M2UA Backhaul Application Server Messages ASP Up ASP Down ASP Active ASP Inactive State Control ASP-Active ASP-Active-Old ASP-Active-New ASP-Up ASP-Down Case 2: M2UA Peer-Peer Application Server Messages Not applicable – covered by alignment / changeover procedures) State Control Link Out-Of-Service Link Alignment Link In-Service Link Congestion Onset Link Congestion Abatement Link Remote Processor Outage Contrasting M2UA Case 1 and Case 2 • Dissimilar functions makes it hard on the reader !

  7. M2UA Peer-Peer Adaptation • Proposal: Split out Backhaul and Peer-Peer Cases • M2UA Backhaul • draft-ietf-sigtran-m2ua-03 • M2UA Peer-Peer • draft-george-sigtran-m2peer-00 • Requested Action • Add M2UA Peer-Peer as SIGTRAN work item • Unique Port and SCTP Protocol Ids • Mail List Issues For Resolution • Multiple Streams per Link (SLS basis) • Proving Period Functionality (Optional) • SCTP Peer-Peer Association Setup (Collision Resolution)

  8. Backup Slides

  9. Layered Communications - OSI Model Layer N+1 Layer N+1 .response .indication .request .confirm Layer N Primitives Layer N SAP (Service Access Point) Layer N Protocol (Protocol DataUnits) Layer N Connection Endpoints Layer N Connections Management Functions Bearer Functions Bearer Functions Management Functions Layer N Layer N Layer N-1 SAP Layer N-1 Layer N-1

  10. Standard SS7 MTP3 Layer Peer User Layers MTP3 User Layers MTP3 Primitives Unitdata (DPC, SLS, Priority) .request, .indication MTP Pause / Resume (DPC) .indication MTP Status (DPC, Congestion Level) .indication MTP Restart Begin / End ( ) .indication MTP3 Protocol DataUnits Message (MSU) Transfer User Part Unavailable Transfer Prohibited / Restricted / Allowed (No Connections Defined) Peer MTP3 Layer Transfer Controlled / RouteSet Congestion Test MTP3 (Network) Layer Changeover / Changeback M2UA / SCTP / IP MTP2 SAAL Peer Link Layers MTP Link Layers

  11. Standard SS7 MTP2 Layer Peer User Layer MTP2 User Layer (MTP3) MTP2 Primitives Data (Length) .request, .indication Link Start / Stop .request, .indication Link Status (State) .indication Data Retrieval (SN) .request, .indication MTP2 Protocol DataUnits MessageSignal Unit (MSU) Link Status Signal Unit (LSSU) Fill In Signal Unit (FISU) Peer MTP2 Layer MTP2 Datalink Layer MTP2 Connection (Datalink) T1E1 Chan DS0A V.35 Peer MTP1 Link Layers MTP1 Link Layers

  12. MTP2 Adaptation Layer Variants Peer MTP3 Layer MTP3 Layer (MTP2 User) MTP2 Primitives AS Data (Length) .request, .indication Link Start / Stop .request, .indication STP/SCP ( Backhaul ) Link Status (State) .indication Data Retrieval (SN) .request, .indication SG MTP2 Protocol DataUnits MessageSignal Unit (MSU) Link Status Signal Unit (LSSU) Peer MTP2 Layer MTP2 Connection (Datalink) MTP2 Datalink Layer IP Network T1E1 Chan DS0A V.35 Peer MTP1 Link Layers ( Peer-Peer ) MTP1 Link Layers

  13. Standard SS7 Layer Summary Signalling System • TCAP Application • Remote Operation Invocation, Parameter Encoding • Application Transaction Control • Example Application: LNP Ported Number Translation • SCCP Layer • Network Application Subsystem Addressing • Global Title Translation (TN Digits -> Subsystem Address) • Remote Subsystem Status Management • MTP3 Layer • Network PointCode Addressing • PointCode Relay Routing, Re-routing, Multi-Link Loadsharing • Link, LinkSet, RouteSet Status Management • MTP2 Layer • Link alignment, proving, error-rate monitoring • MSU Seq# / CRC generation / checking • MSU queuing / dequeuing, retrieval, congestion monitoring • MSU delineation, zero insertion, transmit / receive, re-transmit • Physical Layer • Physical connectivity (e.g. V.35) • Point-to-point bitstream transmit / receive TCAP Application SCCP MTP3 MTP2 PHY

  14. MTP2 User Adaptation Layer: Case 2Ram DantuSIGTRAN Working GroupNovember 9, 1999

  15. MTP2 User Adaptation Layer: Case2 Ram.Dantu - 1999-11-09

  16. Overview • Background: SS7-IP Interface Adaptation Options • Problem Definition (Case1 and Case2) • Case 1: One application of M2UA • SSCOPMCE based solution for Case 2 • Case2: SCTP based solution for STP-IPSCP Interface • Overview of Solution • Link Changeover • Link Proving • Congestion Detection • Emergency Alignment • Conclusions Ram.Dantu - 1999-11-09

  17. Background:SS7-IP Adaptation Layer Options ISUP/SCCP SS7 MTP3 ISUP/SCCP Q.923 MTP3 Q.2140 MTP2UA MTP3UA Q.921UA ITU SSCOPMCE SCTP SCTP SCTP IETF Sigtran UDP UDP UDP SAAL UDP ATM/IP IP IP IP ATM IP E-Net/DS1/DS3/OC3 E-Net/DS1/DS3/OC3 E-Net/DS1/DS3/OC3 E-Net/DS1/DS3/OC3 Ram.Dantu - 1999-11-09

  18. Problem Definition • A protocol M2UA (MTP2 User Adaptation Layer) is being defined by IETF Sigtran Group. The users of this layer are MTP3 and a MTP2-backhauling layer (Case1). One application is the inter working of MTP3 layer and IP networks seamlessly similar to MTP3 layer and MTP2 layer in SS7 network (Case2). In particular, this interface is useful between STP and IP enabled SCPs (IPSCP). To this end, several primitives and procedures are defined for MTP2 User Adaptation Layer. Ram.Dantu - 1999-11-09

  19. Case1 MTP3 MTP2UA SCTP UDP IP Signaling Transfer OR Media Gateway MTP2UA SCTP UDP IP Media Gateway Controller MTP3 MTP2 Signaling Gateway IP Network MTP2 Ram.Dantu - 1999-11-09

  20. Case1 • Backhauling signaling traffic at layer 2 to the Media Gateway Controller. • Using MTP2 user adaptations layer as an extension of MT2 link layer • SGW has no point code and not visible in SS7 network Ram.Dantu - 1999-11-09

  21. SSCOPMCE Solution for High Speed Link STP SCP MTP3 Q.2140 SSCOPMCE ATM MTP3 Q.2140 SSCOPMCE ATM ATM Link Ram.Dantu - 1999-11-09

  22. SSCOPMCE Solution • A Solution for high speed interface between two STPs or between STP and SCP. • SSCOPMCE is a similar transport protocol like SCTP • SSCOPMCE solution is primarily meant for ATM but Interface between SSCOPMCE and IP requires considerable work (under progress) • SCTP has several additional features. Ram.Dantu - 1999-11-09

  23. TCAP SCCP MTP3 MTP2 SCCP MTP3 MTP2 SCP MTP3 MTP2 MTP3 MTP2 SCCP MTP3 MTP2 SSP MTP3 MTP2 SCCP MTP3 MTP2UA SCTP MTP3 MTP2UA SCTP MTP3 MTP2UA SCTP MTP3 MTP2UA SCTP TCAP SCCP MTP3 MTP2UA SCTP STP STP TCAP SCCP MTP3 MTP2UA SCTP IPSSP IPSCP Case2: STP-IPSCP Interface Ram.Dantu - 1999-11-09

  24. MTP2 Functions Signal unit deliminations Signal unit alignment Signal unit detections Signal unit error corrections Signaling link initial alignment Signaling link error monitoring Flow control Sequence numbering Cyclic Redundancy Check Preventive Cyclic Retransmission Data Retrieval Congestion Management MTP3 Functions Link activation Link restoration Link deactivation Change over Change back Emergency change over MTP restart Transfer prohibited Transfer allowed Transfer restricted Transfer controlled Signaling-route-set-test Signaling-route-set-congestion-test Transfer cluster prohibited Transfer cluster allowed Transfer cluster restricted Cluster-route-set-test MTP2 and MTP3 Functions Ram.Dantu - 1999-11-09

  25. M2UA: Case2 • High speed IP link between SEP/STP and STP/SCP • New functions are added to M2UA. In particular, M2UA supporting SS7 link management features. • Enhancements • Mapping of sequence numbers between SS7 Network and IP Network • Additional primitives Data Retrieval during link change over • Additional primitives for Link proving • Additional primitives for Congestion Detection • Additional primitives for Emergency alignment • Procedures for Data Retrieval during link change over • Procedures for Link proving • Procedures for Congestion Detection • Procedures for Emergence Alignment Ram.Dantu - 1999-11-09

  26. MTP3-M2UA Primitives M2UA MTP3 Received Message Link Congested Primitives Link Congestion Ceased Emergency Emergency Ceased STOP Communicating To Peer START Communicating To Peer Link Available Link Out Of Service Flush Buffers Continue Retrieve_BSNT BSNT Confirm Retrieval_Reqest_And FSNC Retrieved Messages Retrieved Complete BSNT Delivery of BSTN Value BSNT_Not_Retrievable Ram.Dantu - 1999-11-09

  27. M2UA-SCTP Primitives INITIALISE ASSOCIATE UDP SCTP UDP Port Terminate SEND (associates ID, buffer address Byte count (mode flags) (context) (stream ‘D) RECEIVE (buffer address, byte count) (association ID) (max size of data to be released) STATUS (association ID) Status date (receive windows size, send window size, connecting state, number of buffers awaiting acknowledgment, number of buffers pending transmit, Round trip time on all active interfaces Ram.Dantu - 1999-11-09

  28. M2UA – SCTP Primitives Data Arrive SEND FAILURE SCTP NETWORK STATUS CHANGE Communication up Communication Lost Ram.Dantu - 1999-11-09

  29. Link Changeover STP/SCP SEP/SCP SS7 network Internal IP Transport Leased IP Network 1. If there is a link fail, link can change over 2. If link is congested then also there can be change over 3. Change over for links of unequal bandwidth for further study Ram.Dantu - 1999-11-09

  30. Link Changeover MTP2UA SCTP SCTP MTP2UA MTP3 MTP3 Communication lost Link out of service TX Find gaps in the received msgs (numbered before first gap) Retrieve BSN Indicate BSN COO (BSN) Relieve BSN Indicate BSN COA (BSN) Go through the transmit queue and find unack and unsent msg. Retrieve FSN 15 7 0 0000000 FSN Not Retrievable Last 7 bits are used for FSN/BSN Retrieval Msg - Extending to 24 bits for further study Retrieval Complete Ram.Dantu - 1999-11-09

  31. Link in service Link Proving MTP2UA SCTP SCTP MTP2UA MTP3 MTP3 1. During proving, only unordered service is considered. This means message is delivered immediately. 2. Proving time is configurable. 3. Estimated - parameters are compared with performance requirements of the application that opened the stream. 4. Link Proving is done on both sides. Communication Emergency Ceased Emergency Up No. of messages for “n” sec Status (or heartbeat RTT RTT Status “n” Sec Estimate - average delay - packet loss - etc., Link In Service Communications link up Link is same RTT Ram.Dantu - 1999-11-09

  32. Status Status Status Polled for certain time till the congestion is ceased (implementation specific) Congestion ceased Congestion Detection MTP2UA SCTP SCTP MTP2UA MTP3 MTP3 Send failure Send failure 3 consecutive failures (implemen- tation dependent) Send failure Congestion Detected Terminate Terminate Successful Communication Lost Link Out of Service (Link Change Over Procedures are Started) Link brought back to service after proving Ram.Dantu - 1999-11-09

  33. Emergency Alignment MTP2UA SCTP MTP3 Emergency Disable proving Emergency Ceased Enable proving Ram.Dantu - 1999-11-09

  34. Conclusions • With wireless and other new configurations, SCPs require high bandwidth links. A high speed link based on SCTP/IP is defined between STPs as well as STP and SEP/SCPs. M2UA seems to be a good fit for interface between SS7 and IP networks. • SCP applications require reliable, available, and proved links. To this end, new primitives/procedures are defined in M2UA. • Minor enhancements are made to SCTP for supporting this feature. M2UA document will be modified to clearly distinguish the Case1 and Case2 solutions. Ram.Dantu - 1999-11-09

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