Page 1 March 29, W. DavisALCATEL USA M2UA Peer-Peer Adaptation Layer SIGTRAN Working Group March 29, 2000

Page 2 March 29, W. DavisALCATEL USA 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

Page 3 March 29, W. DavisALCATEL USA M2UA Case 1 (Backhaul) Architecture SEP - SS7 Signaling EndpointNIF - Nodal Interworking Function SG - Signaling GatewaySCTP - Simple Control Transmission Protcol SEPSG SS7 Appl MTP3 MTP2 MTP1 MTP2 M2UA SCTP MTP1 IP M2UA SCTP IP MGC SS7 IP NIF IP Network MTP2 Primitives Backhaul SS7 Appl

Page 4 March 29, W. DavisALCATEL USA M2UA Case 2 (Peer-Peer) Architecture SEP - SS7 Signaling Endpoint SG - Signaling GatewaySCTP - Simple Control Transmission Protcol SEPSG SS7 Appl MTP3 MTP2 MTP1 MTP2 M2UA SCTP MTP1 IP M2UA SCTP IP MGC SS7 IP IP Network Peer-to-Peer SS7 Appl MTP3 Link Protocol

Page 5 March 29, W. DavisALCATEL USA Contrasting M2UA Case 1 and Case 2  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

Page 6 March 29, W. DavisALCATEL USA Contrasting M2UA Case 1 and Case 2  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  Dissimilar functions makes it hard on the reader !

Page 7 March 29, W. DavisALCATEL USA 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)

Page 8 March 29, W. DavisALCATEL USA Backup Slides

Page 9 March 29, W. DavisALCATEL USA Layered Communications - OSI Model Layer N Layer N Connections Layer N Layer N Protocol (Protocol DataUnits) Layer N SAP (Service Access Point) Layer N-1 Layer N-1 SAP Layer N+1 Layer N-1 Bearer Functions Management Functions Bearer Functions Management Functions Layer N Primitives Layer N Connection Endpoints.request.confirm.response.indication

Page 10 March 29, W. DavisALCATEL USA Standard SS7 MTP3 Layer MTP3 (Network) Layer (No Connections Defined) MTP3 User Layers MTP2 SAAL M2UA / SCTP / IP MTP Link Layers Unitdata (DPC, SLS, Priority).request,.indication Changeover / Changeback Message (MSU) Transfer Transfer Controlled / RouteSet Congestion Test Transfer Prohibited / Restricted / Allowed User Part Unavailable MTP3 Protocol DataUnits MTP Pause / Resume (DPC).indication MTP Status (DPC, Congestion Level).indication MTP Restart Begin / End ( ).indication Peer MTP3 Layer Peer User Layers Peer Link Layers MTP3 Primitives

Page 11 March 29, W. DavisALCATEL USA Standard SS7 MTP2 Layer MTP2 Datalink Layer MTP2 User Layer (MTP3) DS0A V.35 T1E1 Chan MTP1 Link Layers Data (Length).request,.indication MessageSignal Unit (MSU) Fill In Signal Unit (FISU) Link Status Signal Unit (LSSU) MTP2 Protocol DataUnits Link Start / Stop.request,.indication Link Status (State).indication Data Retrieval (SN).request,.indication Peer MTP2 Layer Peer User Layer Peer MTP1 Link Layers MTP2 Primitives MTP2 Connection (Datalink)

Page 12 March 29, W. DavisALCATEL USA MTP2 Adaptation Layer Variants MTP2 Datalink Layer MTP3 Layer (MTP2 User) DS0A V.35 T1E1 Chan MTP1 Link Layers MessageSignal Unit (MSU) Link Status Signal Unit (LSSU) MTP2 Protocol DataUnits Peer MTP2 Layer Peer MTP3 Layer Peer MTP1 Link Layers MTP2 Connection (Datalink) SG AS STP/SCP ( Peer-Peer ) IP Network Data (Length).request,.indication Link Start / Stop.request,.indication Link Status (State).indication Data Retrieval (SN).request,.indication MTP2 Primitives ( Backhaul )

Page 13 March 29, W. DavisALCATEL USA Standard SS7 Layer Summary Signalling System SCCP PHY MTP3 MTP2  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

Page 14 March 29, W. DavisALCATEL USA MTP2 User Adaptation Layer: Case 2 Ram Dantu SIGTRAN Working Group November 9, 1999

Page 15 March 29, W. DavisALCATEL USA MTP2 User Adaptation Layer: Case2 Ram.Dantu

Page 16 March 29, W. DavisALCATEL USA 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

Page 17 March 29, W. DavisALCATEL USA Background: SS7-IP Adaptation Layer Options ISUP/SCCP MTP3 MTP2UA SCTP UDP IP E-Net/DS1/DS3/OC3 ISUP/SCCP MTP3UA SCTP UDP IP E-Net/DS1/DS3/OC3 Q.923 Q.921UA SCTP UDP IP E-Net/DS1/DS3/OC3 IETF Sigtran SS7 MTP3 Q.2140 SSCOPMCE UDP IP E-Net/DS1/DS3/OC3 ITU ATM/IP SAAL ATM Ram.Dantu

Page 18 March 29, W. DavisALCATEL USA 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

Page 19 March 29, W. DavisALCATEL USA Case1 Signaling Transfer OR Media Gateway Signaling Gateway IP Network Media Gateway Controller MTP3 MTP2 MTP3 MTP2UA SCTP UDP IP MTP2UA SCTP UDP IP Ram.Dantu

Page 20 March 29, W. DavisALCATEL USA 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

Page 21 March 29, W. DavisALCATEL USA SSCOPMCE Solution for High Speed Link MTP3 Q.2140 SSCOPMCE ATM MTP3 Q.2140 SSCOPMCE ATM ATM Link STPSCP Ram.Dantu

Page 22 March 29, W. DavisALCATEL USA 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

Page 23 March 29, W. DavisALCATEL USA Case2: STP-IPSCP Interface SSP TCAP SCCP MTP3 MTP2 MTP3 MTP2 IPSSP STP MTP3 MTP2UA SCTP TCAP SCCP MTP3 MTP2UA SCTP MTP3 MTP2 MTP3 MTP2 MTP3 MTP2UA SCTP MTP3 MTP2UA SCTP STP SCCP MTP3 MTP2 SCCP MTP3 MTP2 SCP TCAP SCCP MTP3 MTP2UA SCTP SCCP MTP3 MTP2UA SCTP IPSCP Ram.Dantu

Page 24 March 29, W. DavisALCATEL USA MTP2 and MTP3 Functions  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 Ram.Dantu

Page 25 March 29, W. DavisALCATEL USA 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

Page 26 March 29, W. DavisALCATEL USA MTP3-M2UA Primitives MTP3 Received Message Link Congested 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 PrimitivesPrimitives M2UA Ram.Dantu

Page 27 March 29, W. DavisALCATEL USA M2UA-SCTP Primitives UDPUDP SCTPSCTP UDP Port INITIALISE ASSOCIATE 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

Page 28 March 29, W. DavisALCATEL USA SCTPSCTP SEND FAILURE NETWORK STATUS CHANGE Communication up Data Arrive Communication Lost Ram.Dantu M2UA – SCTP Primitives

Page 29 March 29, W. DavisALCATEL USA SEP/SCP STP/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 Link Changeover

Page 30 March 29, W. DavisALCATEL USA MTP3 MTP2UASCTP MTP2UAMTP3 Communication lost Link out of service Retrieve BSN TX Find gaps in the received msgs (numbered before first gap) Indicate BSN COO (BSN) Relieve BSN Indicate BSN COA (BSN) Retrieve FSN FSN Not Retrievable Retrieval Msg Retrieval Complete Go through the transmit queue and find unack and unsent msg Last 7 bits are used for FSN/BSN - Extending to 24 bits for further study Link Changeover Ram.Dantu

Page 31 March 29, W. DavisALCATEL USA Link Proving MTP3 MTP2UASCTP MTP2UAMTP3 Communication Status (or heartbeat Link In Service Link in service 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. Emergency CeasedEmergencyEmergency CeasedEmergency Up Status “n” Sec Estimate - average delay - packet loss - etc., Communications link up Link is same No. of messages for “n” sec RTT Ram.Dantu

Page 32 March 29, W. DavisALCATEL USA MTP3 MTP2UASCTP MTP2UAMTP3 Send failure Congestion Send failure Detected Send failure 3 consecutive failures (implemen- tation dependent) Polled for certain time till the congestion is ceased (implementation specific) Status Congestion ceased Terminate Terminate Successful Communication Lost Link Out of Service (Link Change Over Procedures are Started) Link brought back to service after proving Ram.Dantu Congestion Detection

Page 33 March 29, W. DavisALCATEL USA MTP3 MTP2UASCTP Emergency Ceased Enable proving Disable proving Ram.Dantu Emergency Alignment

Page 34 March 29, W. DavisALCATEL USA 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