The MIB for MTP3 User Adaptation (M3UA) and SCCP User
Adaptation (SUA) for Cisco's IP Transfer Point (ITP)
implementation.

The Cisco IP Transfer Point (ITP) is a hardware and
software solution that transports SS7 traffic using
IP. Each ITP node provides function similar to SS7
signaling point.   

The relevant ITU documents describing this technology
is the ITU Q series, including ITU Q.700: Introduction
to CCITT Signaling System No. 7 and ITU Q.701
Functional description of the message transfer part
(MTP) of Signaling System No. 7.

The relevent information about M3UA and SUA is
available at the IETF:
http://www.ietf.org/html.charters/sigtran-charter.html

This MIB consists of the following tables:
  M3UA/SUA (XUA) Instance Table
  M3UA/SUA (XUA) Instance Local IP Table
  Signaling Gateway Mate Table
  Signaling Gateway Mate Remote IP Table
  Application Server Process (ASP) Table
  Application Server Process (ASP) Remote IP Table
  Application Server Process (ASP) Statistics Table
  Application Server (AS) Table
  ASP-AS Table
  ASRoute Table
  ASRouteAs Table

Abbreviations:
AS    - Application Server
ASP   - Application Server Process
ASPAC - ASP ACtive message
ASPDN - ASP Down message
ASPIA - ASP InActive message
ASPUP - ASP UP message
CIC   - Circuit Identifier Code for ISUP
CLLI  - Common Language Location Codes
DPC   - Destination Point Code
DAUD  - Destination AUDit
DAVA  - Destination AVAilable
DUNA  - Destination UNAvailable
DUPU  - Destination User Part Unavailable
ERR   - Error message
GTT   - Global Title Translation
HLR   - Home Location Registry
ISDN  - Integrated Services Digital Network
ISUP  - ISDN User Part
M3UA  - MTP3 User Adaptation
MGC   - Media Gateway Controller used in VoIP
MSU   - Message Signal Unit
MTP   - Message Transport Protocol
MTP2  - Layer 2 of Message Transport Protocol
MTP3  - Layer 3 of Message Transport Protocol
NMS   - Network Management System
OPC   - Originating Point Code
PC    - Point Code
QOS   - Quality Of Service
SCCP  - Signaling Connection Control Part
SCP   - Service Control Point (SS7)
SCON  - Signaling link CONgestion
SCON0 - Signaling link CONgestion level 0 (no congestion)
SCON1 - Signaling link CONgestion level 1
SCON2 - Signaling link CONgestion level 2
SCON3 - Signaling link CONgestion level 3
SG    - Signaling Gateway
SGM   - Signaling Gateway Mate
SGMP  - Signaling Gateway Mated Protocol
SCTP  - Stream Transmission Protocol(RFC 2960)
SI    - Signaling Indicator
SIO   - Service Indicator Octet (SS7)
SNMM  - Signaling Network Management Message
SSN   - Subsystem Number for SCCP
SUA   - SCCP User Adaptation
TUP   - Telephone User Part
TT    - Title Translation
VIP   - Versatile Interface Processor
XUA   - M3UA, SUA or SGMP

Brief description:

The Signaling Gateway (SG) on the ITP receives the SS7
Message Signal Units(MSUs), converts them to M3UA/SUA
messages and routes them to the ASPs over SCTP/IP
association. The routing of the message depends on the
routing information present in the message and the 
routing keys configured as part of the ASes.

There can be one or more instances of M3UA/SUA at the
SG. These instances are identified by a unique port
number. Each of these instances can have one or more
IP addresses which form 'local' end of the multi-homing
SCTP association.

The Application Server Process (ASP) is a remote entity
which has its own port number and one or more IP
addresses to form the 'remote' end of the multi-homing
SCTP association. Examples of ASPs are MGCs, IP SCPs or
IP HLRs.

Application Server (AS), as described in section
'1.2 Terminology' of M3UA/SUA draft, is a logical
entity serving a specific Routing Key. An example of
an AS is a virtual switch element handling all call
processing for a unique range of PSTN trunks,
identified by an SS7 SIO/DPC/OPC/CIC_range. Another
example is a virtual database element, handling all
HLR transactions for a particular SS7 DPC/OPC/SCCP_SSN
combination. The AS contains a set of one or more
unique ASPs of which one or more is normally actively
processing traffic. Note that there is a 1:1
relationship between an AS and a Routing Key.

An ASP can serve one or more ASes and an AS can have
one or more ASPs. An ASP while serving an AS can be
active, inactive or down. When one or more ASPs for
an AS is active, the AS is active. When all ASPs for
an AS are inactive, the AS is inactive. The state of
the AS is maintained in one object, whereas, the state
of an ASP is maintained for each AS that it serves in
ASP-AS table.

The SGs are always deployed in mated pairs to provide
high availability and redundancy. The SG mates exchange
the state of ASes. When an AS is down on one SG, it can
route the SS7 message to its mate which can properly
route that SS7 message.