Transcript M3UA (MTP3-User Adaptation Layer) <draft-ietf-sigtran-m3ua-02.txt>

M3UA (MTP3-User Adaptation Layer)
<draft-ietf-sigtran-m3ua-02.txt>
*******
SS7
******
IP
*******
* SP *------------* SG *------------*IP SEP*
*******
******
*******
E
x
a
m
p
l
e
+------+
| ISUP |
+------+
| MTP |
| L3 |
| L2 |
| L1 |
|
|
+------+
<--------------------------->
+-------------+
<----> | MTP | M3UA | <---->
<----> | L3 +------+ <---->
<----> | L2 | SCTP | <---->
<----> | L1 +------+ <---->
|
| UDP | <---->
+-------------+
+------+
| ISUP |
+------+
| M3UA |
+------+
| SCTP |
+------+
| 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, ..)
SCTP - Simple Common Transmission Protocol
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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
• N+k 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
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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 n+k 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
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Changes - Continued
• Added State Change Notification SG-ASPs in AS to allow better
coordination
• Use Cases Expanded
• Added Optional M3UA-level Heartbeat
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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]
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Current Issues
• ASP "graceful shutdown" case required? [M3UA, M2UA, IUA]
Provide 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?
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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?
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Status & Work Plan
• <draft-ietf-sigtran-m3ua-02.txt> 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
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