M3UA (MTP3-User Adaptation Layer)

1
M3UA (MTP3-User Adaptation Layer)

• ltdraft-ietf-sigtran-m3ua-02.txtgt
• SS7 IP
• SP ------------ SG ------------IP SEP
• ------ ------
• ISUP lt---------------------------gt ISUP
• ------ ------------- ------
• MTP lt----gt MTP M3UA lt----gt M3UA
• L3 lt----gt L3 ------ lt----gt ------
• L2 lt----gt L2 SCTP lt----gt SCTP
• L1 lt----gt L1 ------ lt----gt ------
• UDP lt----gt UDP
• ------ ------------- ------
• SP - SS7 Signaling Point (SS7 SEP or STP)
• IP SEP - IP-based Node (e.g., MGC, IP SCP, )
• User - MTP3-User Protocol (e.g., ISUP, SCCP, TUP,
  ..)

Example
2
M3UA Principles

• Supports MTP3-User Interface and Services
  (Transparent to MTP3-User)
• Open/Closes SCTP Transport Associations
• Starts/Stops Traffic across an open SCTP
  Association
• Allows Flexible Message Distribution (e.g., SS7
  OPC/DPC/SLS/CIC) to ASPs
• ASP Fail-over support within AS list
• Nk Redundancy Support
• Load-balancing Support
• Allows ASP signalling through redundant SGs to
  SS7 Network
• Does not re-encode MTP-3 Routing Label / SIO in
  MTP-Transfer primitive
• SCTP Stream Mapping

3
Changes in M3UA Issue 2

• Removed explicit SCN Protocol Identifier
  Protocol Identifier Parameters. Now use MTP3 SIO
  and/or Network Appearance (if required) 
• Cleaned up SG configuration terminology (i.e.,
  Routing Key, AS, ASP, Routing Context, SPMC,
  Network Appearance)
• Expanded to include nk redundancy, load-sharing
• Better description of fail-over operation
• Added Ability for ASP to route SS7 traffic across
  redundant SGs
• Added Point Code Lists in SSNM Messaging (DUNA,
  DAVA, SCON)
• Made SSNM DAUD (Audit) more flexible

4
Changes - Continued

• Added State Change Notification SG-ASPs in AS to
  allow better coordination
• Use Cases Expanded
• Added Optional M3UA-level Heartbeat

5
Current Issues

• Impact of a future registration protocol
  component M3UA, M2UA, IUA 
• Implementation-dependent Parameters or Messages
  M3UA, M2UA, IUA (Agreed but not added
  yet) 
• New SS7 Network Unavailable message? M3UA
  (Agreed but not added yet) 
• Nodal inter-working function still confusing?
  M3UA
• More Use cases required in Section 4
  (Agreed but not added yet)
• Timer provisional values required. M3UA, M2UA,
  IUA

6
Current Issues

• ASP "graceful shutdown" case required? M3UA,
  M2UA, IUAProvide consistent use of MUST,
  SHALL, MAY etc as in rfc see SCTP.
• New Items from List
• Add possible case of SG sending UPU message into
  SS7 network when it determines that all ASPs in
  SPMC is no longer available, at least for a
  particular User Part.
• TCP text proposal. Sentence or two in
  introduction of Adaptation layer docs and later
  Section/Annex with more info as agreed on Design
  Team call? 
• IP to IP M3UA? Section possible to describe M3UA
  operation where two communicating points are in
  IP network with no need for an SG. Probably
  start with the idea that DUNA/DAVA/SCON/UPU and
  related procedures are omitted. Basis for BICC
  STC?

7
Current Issues

• Specify explicitly Data recovery from a failed
  SCTP Association (e.g., to ASP1) to new SCTP
  Association (e.g., to to ASP2) do we attempt
  this. Smells like SS7 Normal Change-over is
  this appropriate? Recover Unsent (Tx Buffer)
  only or also Sent/Unacked.(RTx Buffer).
  Stringent requirements for duplicated MSUs may
  impact choice. Other Ideas
•  SCON from ASP to SG to indicate ASP nodal
  congestion?

8
Status Work Plan

• ltdraft-ietf-sigtran-m3ua-02.txtgt currently
  available
• Issues List substantially reduced at the
  Washington Design Team Meeting
• Draft 03 addressing above issues end-of-April at
  latest
• Possible Last Call