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Dialogic® SS7 Protocols 
M2PA Programmer’s Manual
2 
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The names of actual companies and products mentioned herein are the trademarks of their respective owners. 
Publication Date: August 2007 
Document Number: 05-2407-002, Issue 3
Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3 
Contents 
1 Introduction.............................................................................................................5 
1.1 Related Documentation.......................................................................................5 
2 Functional Overview.................................................................................................6 
2.1 M2PA Module Overview........................................................................................6 
2.2 Feature Overview................................................................................................6 
2.3 General Description.............................................................................................7 
3 Message Reference...................................................................................................8 
3.1 Protocol Requests from M2PA to SCTP...................................................................8 
3.1.1 SCTP_MSG_ACTIVATE – SCTP Activate Association Request...........................9 
3.1.2 SCTP_MSG_SHUTDOWN – SCTP Shutdown Association Request....................10 
3.1.3 SCTP_MSG_ABORT – SCTP Abort Association Request..................................11 
3.1.4 SCTP_MSG_TX_REQ – SCTP Data Transfer Request.....................................12 
3.2 Protocol Indications from SCTP to M2PA................................................................13 
3.2.1 SCTP_MSG_STATUS_CHANGE – STCP Association Status Change..................14 
3.2.2 SCTP_MSG_RX_IND – STCP Association Data Transfer Indication..................15 
3.2.3 SCTP_MSG_NETWORK_STATUS – STCP Association Network Status...............16 
3.2.4 SCTP_MSG_CONG_STATUS – STCP Association Congestion Status.................17 
3.3 Protocol Requests from MTP3 to M2PA..................................................................18 
3.3.1 API_MSG_TX_REQ – Message for Transmission Request...............................19 
3.3.2 SS7_MSG_START – M2PA Link Start Request..............................................20 
3.3.3 SS7_MSG_STOP – M2PA Link Stop Request................................................21 
3.3.4 SS7_MSG_EMGCY – M2PA Set Emergency Request.....................................22 
3.3.5 SS7_MSG_EMGCY_CLRD – M2PA Cancel Emergency Request........................22 
3.3.6 SS7_MSG_RTV_BSNT – M2PA BSNT Retrieval Request.................................23 
3.3.7 SS7_MSG_RTVL_REQ – M2PA Retrieval Request..........................................24 
3.3.8 SS7_MSG_LOC_PR_OUT – M2PA LPO Request............................................25 
3.3.9 SS7_MSG_LOC_PR_OK – MTP2 LPO Recovered Request...............................25 
3.4 Protocol Indications from M2PA to MTP3................................................................26 
3.4.1 API_MSG_RX_IND – Received Message Indication.......................................27 
3.4.2 SS7_MSG_IN_SVC – M2PA In Service Indication.........................................28 
3.4.3 SS7_MSG_OUT_SVC – M2PA Out of Service Indication.................................29 
3.4.4 SS7_MSG_REM_PR_OUT – M2PA RPO Indication.........................................29 
3.4.5 SS7_MSG_REM_PR_OK – M2PA RPO Cleared Indication...............................30 
3.4.6 SS7_MSG_RXD_BSNT – M2PA BSNT Indication...........................................31 
3.4.7 API_MSG_RTVD_MSG – M2PA Retrieved Message Indication.........................32 
3.4.8 SS7_MSG_RTVL_COMPL – M2PA Retrieval Complete Indication.....................33 
3.4.9 MTP_MSG_RTVL_NOT_POS – M2PA Retrieval Failure Indication.....................34 
3.4.10 MTP_MSG_LINK_CONG – M2PA Link Congested Indication............................35 
3.4.11 MTP_MSG_LINK_UNCONG – M2PA Congestion Cleared Indication..................36 
3.4.12 MTP_MSG_FLUSH_ACK – M2PA Flush Acknowledgement Indication................37 
4 Non-Primitive Interface...........................................................................................38 
4.1 Confirmation Message Status Values....................................................................38 
4.2 Non-Primitive Interface Messages........................................................................38 
4.2.1 M2P_MSG_CONFIG – Configure M2PA Module.............................................39 
4.2.2 M2P_MSG_CNF_LINK – M2PA Link Configuration Request.............................40 
4.2.3 M2P_MSG_END_LINK – M2PA Link End Request..........................................42 
4.2.4 M2P_MSG_TRACE_MASK – TRACE MASK Set Request..................................43 
4.2.5 M2P_MSG_R_STATE – READ STATE Read Request.......................................45 
4.2.6 M2P_MSG_R_STATS – READ STATISTICS Read Request...............................47 
4.2.7 M2P_MGT_MSG_EVENT_IND – EVENT Indication.........................................49 
4.2.8 M2P_MSG_ERROR_IND – ERROR Indication................................................50 
4.2.9 M2P_MGT_MSG_LINK_STATE – M2PA Link STATE Indication.........................51 
5 Typical Configuration Values....................................................................................52 
6 Message Types.........................................................................................................53 
6.1 Message Type Table...........................................................................................53 
7 Timer Serivces.........................................................................................................54 
7.1 Introduction......................................................................................................54 
7.1.1 KEEP_TIME – Keep Time..........................................................................54
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Contents 
7.1.2 TM_EXP – Timer Expiry............................................................................55 
A Network Address Representation.............................................................................56 
A.1 Network Address Structure for an Invalid Address..................................................56 
A.2 Network Address Structure for Internet Protocol Version 4.......................................56 
Glossary...................................................................................................................57 
Index...............................................................................................................................58 
Tables 
1 Typical Configuration Values.......................................................................................52 
2 Message Types.........................................................................................................53 
Revision History 
Note: The latest released issue of this guide can be found at: 
http://www.dialogic.com/support/helpweb/signaling 
Date Part No. Issue No. Description of Changes 
18-Apr-07 05-2407-002 3 
Changed to Dialogic format. 
Updated the parameters in Section4.2.4, “M2P_MSG_TRACE_MASK” on 
page43. 
Supports configuration of the RFC version and a per link option for the 
support of Draft Version 9. 
This manual is applicable to M2PA Software Core V1.04 or later. 
14-Apr-05 05-2407-001 2 Supports the production release of MP2A software core revision V1.02. Updated the Event Codes table in Section4.2.7 
M2P_MGT_MSG_EVENT_IND - EVENT Indication. 
17-Dec-04 05-2407-001-01 1 Applicable to MP2A software core revision V1.01. 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
Chapter 1:  Introduction 
The M2PA module is an implementation of the IETF SIGTRAN, SS7 MTP2-User Peer-to-Peer Adaptation Layer 
(M2PA). This Programmer's Manual is intended for users developing their own application programs that 
interface with or use the functionality offered by the M2PA module. 
The module uses the services offered by the Stream Control Transmission Protocol (SCTP) to exchange 
signaling messages with remote signaling points. It supports a number of links, each separately configurable 
allowing the user flexibility in configuring the module. 
The M2PA module is intended to be used in conjunction with the Dialogic® SS7 Protocols SCTP and MTP3 
modules, either on hardware platforms from Dialogic or on user-supplied hardware. However, the software is 
portable and the well-defined interface of the module allows it to be used with alternative SCTP and MTP3 
implementations as required. 
This manual provides an overview of the operation of the M2PA module, defines the structure of all messages 
that can be sent to, or issued by, the module and describes all configuration parameters. 
1.1 Related Documentation 
The following documents provide information that is related to the information in this manual: 
•IETF Internet draft SS7 MTP2-User Peer-to-Peer Adaptation Layer 
•IETF RFC 2960 Stream Control Transmission Protocol 
•SCTP Programmer's Manual 
•Software Environment Programmer's Manual 
•SS7 Programmer's Manual for SigTran Host Software 
•ITU-T Q.703 Message Transfer Part Layer 2 
6 
Chapter 2 Functional Overview 
Chapter 2:  Functional Overview 
2.1 M2PA Module Overview 
The services offered by M2PA and SCTP are used to replace those offered by MTP2. The services offered by 
MTP2 can be divided into high- and low-level functions: 
•The high-level functions include: 
—Link state control 
—Initial alignment control 
—Transmission control 
—Reception control 
•The low-level functions include: 
—Signal unit delimitation and alignment 
—Error detection 
—Signal unit error monitoring. 
M2PA may be considered to replace the high-level functions, and SCTP the low-level functions. 
The M2PA module is a full implementation including the following services: 
•Link alignment (normal and emergency) 
•Generation of level 2 header information 
•Buffering transmission and retrieval of Message Signal Units (MSU) 
•Validation and acknowledgement of received signal units 
•Generation and transmission of Link Status Signal Units (LSSU) 
•Congestion control 
M2PA services MTP3 requests and issues indications to MTP3 and to management. The module supports level 
2 monitoring and measurement features. 
2.2 Feature Overview 
Features of the M2PA module include: 
•Implementation of IETF Internet draft M2PA Version 09 
•Configuration options on an M2PA Link basis 
•User interface common with other Dialogic® SS7 Protocols 
•Message oriented interface 
•Full user control of link supervisory functions; reset, blocking and unblocking 
•Support for 24-bit and 7-bit sequence numbers 
•Optional support for multiple congestion levels 
•Support for message retrieval 
•Support for per link statistics 
•Support for normal and emergency proving 
•Support for local and remote processor outage 
•Debug tracing of messages exchanged with SCTP and MTP3 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
2.3 General Description 
The interface to the M2PA module is entirely message-based, using the structured messages documented in 
the Software Environment Programmer’s Manual. The M2PA module is capable of working in conjunction with 
the Dialogic® SS7 Protocols MTP3 module, or, using the interface specified in this manual, M2PA can be used 
in conjunction with third-party MTP3 implementations if required. 
The M2PA module supports multiple logical M2PA links. Each link is maintained independently of the others. 
Links are identified by a level 2 logical link identifier (l2_llid).The l2_llid values are in the range from 0 to 
one less than the number of links supported and are used to identify the link in all messages sent to the 
M2PA module. At configuration time, a level 3 link identifier is associated with each link and this is used in 
indications issued to the MTP3 module. 
8 
Chapter 3 Message Reference 
Chapter 3:  Message Reference 
This chapter describes the individual messages and associated parameters that may be sent or received 
when interfacing to the M2PA module. 
The interface is a message based interface using messages of type MSG as defined in the Software 
Environment Programmer’s Manual. 
These messages are used for the primitive protocol interface with the MTP3 and SCTP modules, and for the 
non-primitive interface to management for the purposes of configuring and managing M2PA signaling links. 
The messages are grouped into the following categories: 
•Protocol Requests from M2PA to SCTP 
•Protocol Indications from SCTP to M2PA 
•Protocol Requests from MTP3 to M2PA 
•Protocol Indications from M2PA to MTP3 
•Management Requests sent to M2PA 
•Management Indications issued by M2PA 
3.1 Protocol Requests from M2PA to SCTP 
Primitive protocol requests are sent from M2PA to SCTP in accordance with published M2PA 
recommendations. 
Note: This section of the manual is applicable only to users intending to write or interface to their own 
SCTP implementation. When using SCTP from the Dialogic® SS7 Protocols, this interface is 
already implemented by the SCTP module. 
The list of protocol requests sent from M2PA to SCTP includes: 
•SCTP Activate Association Request - Servers wait for incoming association or client attempt association 
•SCTP Shutdown Association Request - Gracefully close down association 
•SCTP Abort Association Request - Abort an association 
•SCTP Data Transfer Request - Transmit a data packet 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.1.1 SCTP_MSG_ACTIVATE – SCTP Activate Association Request 
Synopsis 
Move the association from the Configuration state into the Active state. 
Message Format 
Description 
The association is moved from the Configuration state to the Active state, allowing the association to accept 
incoming or start outgoing connection procedures with its peer. 
The module sending the message should request a response and check that all configuration information was 
accepted and that the activation has succeeded. 
At least one peer IP address must be configured prior to activation. 
Once the association has been activated, if the host port is zero, it is configured to an ephemeral port. 
If the association has been configured with a peer port (set to non zero), the association attempts to initiate 
an association with its peer and is indicated to the user by the reception of an association status change 
message detailing a state of Connecting. 
If the association has been configured without a peer port (set to zero), the activated association awaits an 
incoming association from the configured peer. 
Established associations are indicated to the user via the association status message detailing a state of 
Connected. 
Message Header 
Field Name Meaning 
Type SCTP_MSG_ACTIVATE (0x728a) 
Id Association ID 
Src Originating Module ID 
Dst SCTP Module 
rsp_req Used to request a confirmation 
Hclass 0 
Status Non zero on error 
err_info 0 
Len 0
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Chapter 3 Message Reference 
3.1.2 SCTP_MSG_SHUTDOWN – SCTP Shutdown Association Request 
Synopsis 
Attempt to shutdown an association after all outstanding data has been acknowledged. 
Message Format 
Description 
Once shutdown starts, the status of the connection is indicated to the user via the 
SCTP_MSG_ASSOC_STATUS message. 
Once the user has successfully requested that the association be shutdown, all further attempts to send data 
on the association are rejected. 
Once the shutdown has completed, SCTP sends the user an association status message with a status of 
CLOSED and reenters the Unconfigured state. 
Message Header 
Field Name Meaning 
type SCTP_MSG_SHUTDOWN (0x728b) 
id Association ID 
src Originating Module ID 
dst SCTP Module 
rsp_req Used to request a confirmation 
hclass 0 
status Non zero on error 
err_info 0 
len 0
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.1.3 SCTP_MSG_ABORT – SCTP Abort Association Request 
Synopsis 
Initiates the abortion of an association with the loss of all outstanding data. 
Message Format 
Description 
Once an association is aborted, new data is not accepted for transmission and all outstanding data is lost. 
Once the association has shutdown, it sends the user an association status message with a status of CLOSED 
and reenters the Unconfigured state. 
Parameters 
•error 
Error code sent to the peer to indicate the reason for the abort. See RFC2960, Section 3.3.10 for detailed 
descriptions of the possible error codes. 
Message Header 
Field Name Meaning 
type SCTP_MSG_ABORT (0x728c) 
id Association ID 
src Originating Module ID 
dst SCTP Module 
rsp_req Used to request a confirmation 
hclass 0 
status Non zero on error 
err_info 0 
len 2 
Parameter Area 
Offset Size Name 
0 2 error
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Chapter 3 Message Reference 
3.1.4 SCTP_MSG_TX_REQ – SCTP Data Transfer Request 
Synopsis 
Queue a data packet for transmission on an association. 
Message Format 
Description 
Data packets with more than 300 octets are not supported. 
Data packets are rejected if the association is not currently established or an invalid stream ID is used. 
If a response message has been requested, it is returned when either the packet is rejected (see above) or 
the packet has been queued for transmission. The user has no method of determining when its peer has 
acknowledged a specific data packet. 
If the user attempts to send data faster than the peer can accept, SCTP buffers the data. If the amount of 
data exceeds a predetermined value, the user is notified by a congestion status message that indicates 
congestion has occurred. Once the amount of data is dropped to a lower predetermined level, a second 
congestion status message is sent to the user indicating that congestion has abated. If the user continues to 
send data after being notified that congestion has occurred and a second level has been passed, the user will 
be informed that the data sent is being discarded. 
Parameters 
•data 
Octets of data for transmission 
•flags 
SCTP transmission flags. 
•stream 
SCTP stream number for transmission. 
•ppid 
SCTP Payload Protocol Identifier (PPID) 
Message Header 
Field Name Meaning 
type SCTP_MSG_TX_REQ (0xc280) 
id Association ID 
src Originating Module ID 
dst SCTP Module 
rsp_req Used to request a confirmation 
hclass 0 
status 0 
err_info 0 
len data len + 8 
Parameter Area 
Offset Size Name 
0 data len data 
data len 2 flags 
data len +2 2 stream 
data len + 4 4 ppid 
Status Description 
SCTP_UNBUNDLED Do not bundle the packet for first transmission 
SCTP_UNORDERED Use unsequenced delivery
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.2 Protocol Indications from SCTP to M2PA 
Primitive protocol indications are sent from SCTP to M2PA in accordance with published M2PA 
recommendations. 
This section of the manual is applicable only to users intending to write or interface to their own SCTP 
implementation. When using SCTP from the Dialogic® SS7 Protocols, this interface is already implemented 
within the SCTP module. 
The full list of protocol requests sent from SCTP to M2PA includes: 
•STCP Association Status Change - Association status change 
•STCP Association Data Transfer Indication - Received data packet 
•STCP Association Network Status - Change in network status 
•STCP Association Congestion Status - Change in the congestion status of the association
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Chapter 3 Message Reference 
3.2.1 SCTP_MSG_STATUS_CHANGE – STCP Association Status Change 
Synopsis 
A change in the association status has occurred. 
Message Format 
Description 
This message is sent to the user application to indicate a change in state of the association. The status field 
can be one of the values in the following table: 
Parameters 
•i_streams 
Number of SCTP streams allocated for peer to host data transfer 
•o_streams 
Number of SCTP streams allocated for host to peer data transfer 
Message Header 
Field Name Meaning 
type SCTP_MSG_STATUS_CHANGE (0x028d) 
id Association ID 
src Originating Module ID 
dst User Application 
rsp_req 0 
hclass 0 
status status 
err_info 0 
len 4 
Parameter Area 
Offset Size Name 
0 2 i_streams 
2 2 o_streams 
Status Description 
STATUS_CLOSED Association has entered the closed state. 
STATUS_CONNECTING Association is attempting to connect to a peer. 
STATUS_CONNECTED Association is available for data transfer. 
STATUS_CLOSING Association is attempting a graceful shutdown. 
STATUS_RESTART The peer has restarted the association. Data queued by the association 
before it was restarted will be lost.
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.2.2 SCTP_MSG_RX_IND – STCP Association Data Transfer Indication 
Synopsis 
Indicates the arrival of a data packet from the peer. 
Message Format 
Description 
In the event of a data chunk of more then 300 octets being received from its peer, SCTP acknowledges the 
packet as normal. However, the packet is then discarded (the user never sees the packet) and a 
management message is generated. 
Parameters 
•data 
Actual octets of data received. 
•flags 
Combinable SCTP transmission flags. 
•stream 
SCTP stream number for transmission 
•ppid 
SCTP Payload Protocol Identifier (PPID) 
Message Header 
Field Name Meaning 
type SCTP_MSG_RX_IND (0x8281) 
id Association ID 
src Originating Module ID 
dst SCTP Module 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len data len + 8 
Parameter Area 
Offset Size Name 
0 data len data 
data len 2 flags 
data len + 2 2 stream 
data len + 4 4 ppid 
Status Description 
SCTP_UNORDERED Packet used unsequenced delivery
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Chapter 3 Message Reference 
3.2.3 SCTP_MSG_NETWORK_STATUS – STCP Association Network Status 
Synopsis 
Indicates a status change has occurred on a network address within the association. 
Message Format 
Description 
Indicates to the user that either a network address that was previous available is now being marked as 
inactive, or vice versa. The definition of an inactive address is one that has failed to respond to a 
configurable number of sequential heartbeat requests. The status field can be one of the values in the 
following table: 
Parameters 
•ip_type 
The IP address format. See AppendixA, “Network Address Representation”. 
•ip_addr 
The IP address. See AppendixA, “Network Address Representation”. 
Message Header 
Field Name Meaning 
type SCTP_MSG_NETWORK_STATUS (0x028e) 
id Association ID 
src Originating Module ID 
dst User Application 
rsp_req 0 
hclass 0 
status status 
err_info 0 
len 17 
Parameter Area 
Offset Size Name 
0 1 ip_type 
1 16 ip_addr 
Status Description 
ADDRESS_INACTIVE Network address has been marked inactive. 
ADDRESS_ACTIVE Network address has been marked as available for data transfer.
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.2.4 SCTP_MSG_CONG_STATUS – STCP Association Congestion Status 
Synopsis 
Indicates a status change has occurred with regard to transmitting congestion on an association. 
Message Format 
Description 
Sent to the user to indicate the level of congestion on the association has changed. The status field can be 
one of the values in the following table: 
On reception of an SCTP_TX_CONG_ONSET message, the user should reduce the rate at which messages are 
sent to SCTP. If the congestion clears, then an SCTP_TX_CONG_ABATE message is sent and the user can 
continue as before. However, if the level of congestion rises after a SCTP_TX_CONG_ONSET message has 
been sent, the system may send the user an SCTP_TX_CONG_DISCARD message. At this point, SCTP 
discards any data messages sent by the user until the level of congestion has dropped to a safe level and an 
SCTP_TX_CONG_ABATE message is sent. 
Message Header 
Field Name Meaning 
type SCTP_MSG_CONG_STATUS (0x028f) 
id Association ID 
src Originating Module ID 
dst User Application 
rsp_req 0 
hclass 0 
status status 
err_info 0 
len 0 
Status Description 
SCTP_TX_CONG_ABATE Transmission queue is free to accept more messages 
SCTP_TX_CONG_ONSET Transmission queue is experiencing congestion 
SCTP_TX_CONG_DISCARD Transmission queue has been filled to capacity and has started to 
discard messages queued for transmission
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Chapter 3 Message Reference 
3.3 Protocol Requests from MTP3 to M2PA 
Primitive protocol requests are sent from MTP3 to M2PA in accordance with published M2PA 
recommendations. The primitive names used for the M2PA module are closely aligned with the terminology 
used in ITU-T Recommendation Q.703. 
This section of the manual is applicable only to users intending to write or interface to their own MTP3 
implementation. When using MTP3 from the Dialogic® SS7 Protocols, this interface is already implemented 
within the MTP3 module. 
The full list of protocol requests sent from MTP3 to MTP2 includes: 
•API_MSG_TX_REQ – Message for Transmission Request 
•SS7_MSG_START – M2PA Link Start Request 
•SS7_MSG_STOP – M2PA Link Stop Request 
•SS7_MSG_EMGCY – M2PA Set Emergency Request 
•SS7_MSG_EMGCY_CLRD – M2PA Cancel Emergency Request 
•SS7_MSG_RTV_BSNT – M2PA BSNT Retrieval Request 
•SS7_MSG_RTVL_REQ – M2PA Retrieval Request 
•SS7_MSG_LOC_PR_OUT – M2PA LPO Request 
•SS7_MSG_LOC_PR_OK – MTP2 LPO Recovered Request 
When sending messages to M2PA, the user should ensure that the message is sent to the correct 
module_id and the correct Layer 2 Logical Link ID (l2_llid). 
The hdr->id field of the message should be set to the correct l2_llid, which is in the range from zero up to 
one less than the number of signaling links supported by the M2PA instance. 
The hdr->rsp_req field may optionally be used to request a confirmation. If requested, the M2PA module 
confirms acceptance of the primitive by sending the message back to its originator with bit14 cleared in the 
type field of the message. This mechanism is described in detail in the Software Environment Programmer’s 
Manual. 
Note: Normal MTP3 operation does not require a response from M2PA for these primitives. The 
mechanism is useful however when debugging an application. 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.3.1 API_MSG_TX_REQ – Message for Transmission Request 
Synopsis 
Message issued to a board by MTP3 containing SS7 Message Signal Unit (MSU) tor transmission to the 
network on specified signaling link. 
Message Format 
Description 
This primitive is issued by MTP3 to request that M2PA transmit an MTP3 Message on the specified link. The 
parameter area should commence with the MTP Routing Label. 
Parameters 
•MSU data 
MSU data in binary format commencing with the Service Information Octet (SIO). 
Message Header 
Field Name Meaning 
type API_MSG_TX_REQ  (0xcf00) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len Number of octets in MSU 
Parameter Area 
Offset Size Name 
0 len MSU data 
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Chapter 3 Message Reference 
3.3.2 SS7_MSG_START – M2PA Link Start Request 
Synopsis 
Request to start the initial alignment procedure for the specified link. 
Message Format 
Description 
This primitive is issued by MTP3 to request that M2PA commence the initial alignment procedure. If the 
procedure is successful, an In Service indication is issued. If alignment fails, an Out of Service indication is 
issued. 
If an EMERGENCY condition exists, then MTP3 should send an SS7_MSG_EMGCY message to M2PA prior to 
sending the M2PA Link Start Request. 
Changes of EMERGENCY condition can be notified by MTP3 to M2PA both prior to sending the M2PA Link Start 
Request and during link alignment. 
Note: Receipt of a confirmation message (if requested) does not imply that the initial alignment 
procedure has been completed, merely that M2PA has recognized the request to start the 
procedure. 
Message Header 
Field Name Meaning 
type SS7_MSG_START  (0xc204) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req Sending layer’s bit set if response required 
hclass 0 
status 0 
err_info 0 
len 0
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.3.3 SS7_MSG_STOP – M2PA Link Stop Request 
Synopsis 
Request to stop a signaling link. 
Message Format 
Description 
This primitive is issued by MTP3 to request that M2PA stop the operation of a signaling link. The link is taken 
to the Out of Service state without further indications being issued to MTP3. 
Once a link has been stopped, MTP3 may request the Backward Sequence Number Transmitted (BSNT) and 
initiate message retrieval if required. 
Message Header 
Field Name Meaning 
type SS7_MSG_STOP  (0xc205) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req Sending layer’s bit set if response required 
hclass 0 
Status 0 
err_info 0 
Len 0
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Chapter 3 Message Reference 
3.3.4 SS7_MSG_EMGCY – M2PA Set Emergency Request 
Synopsis 
Request to use the emergency proving period on the next attempt at link alignment. 
Message Format 
Description 
This primitive is issued by MTP3 prior to issuing the M2PA Link Start Request or during initial alignment to 
cause the next attempt at link alignment to use the emergency proving period instead of the normal proving 
period. 
3.3.5 SS7_MSG_EMGCY_CLRD – M2PA Cancel Emergency Request 
Synopsis 
Request to cancel a previous M2PA Set Emergency Request. 
Message Format 
Description 
This primitive is issued by MTP3 prior to canceling any previous Emergency requests and causes the next 
attempt at link alignment to use the normal proving period. 
Message Header 
Field Name Meaning 
type SS7_MSG_EMGCY  (0xc207) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req Sending layer’s bit set if response required 
hclass 0 
status 0 
err_info 0 
len 0 
Message Header 
Field Name Meaning 
type SS7_MSG_EMGCY_CLRD  (0xc208) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req Sending layer’s bit set if response required 
hclass 0 
status 0 
len 0
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.3.6 SS7_MSG_RTV_BSNT – M2PA BSNT Retrieval Request 
Synopsis 
Request for BSNT retrieval. 
Message Format 
Description 
This primitive is issued by MTP3 to request the sequence number of the last signal unit to be acknowledged, 
the Backward Sequence Number Transmitted (BSNT). The response is issued by M2PA as an 
SS7_MSG_RXD_BSNT indication. 
Message Header 
Field Name Meaning 
type SS7_MSG_RTV_BSNT  (0xc209) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req Sending layer’s bit set if response required. 
hclass 0 
status 0 
err_info 0 
len 0
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Chapter 3 Message Reference 
3.3.7 SS7_MSG_RTVL_REQ – M2PA Retrieval Request 
Synopsis 
Request retrieval of unacknowledged messages. 
Message Format 
Description 
This primitive is issued by MTP3 to request retrieval of all unacknowledged messages from the 
retransmission buffer and the transmission buffer, commencing with the message containing a sequence 
number immediately following the Forward Sequence Number Confirmed (FSNC) provided in the parameter 
area of the message. These messages can then be retransmitted by MTP3 over an alternative signaling link. 
M2PA responds with zero, one or more API_MSG_RTVD_MSG indications followed by an 
SS7_MSG_RTVL_COMPL indication. Only messages with a FSN greater than the given FSNC are retrieved. 
Parameters 
•FSNC 
Forward Sequence Number Confirmed. This is the sequence number of the first message to be retrieved. 
If this is set to 0x80, then the extended_FSNC field is valid. 
•reserved 
Reserved for future use. 
•extended_FSNC 
Extended Forward Sequence Number Confirmed. A 32-bit value; MSB first. This field is used when 24-bit 
sequence numbers are in use. 
Message Header 
Field Name Meaning 
type SS7_MSG_RTVL_REQ  (0xc20a) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req Sending layer’s bit set if response required. 
hclass 0 
status 0 
err_info 0 
len 6 
Parameter Area 
Offset Size Name 
0 1 FSNC 
1 1 reserved 
2 4 extended_FSNC 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.3.8 SS7_MSG_LOC_PR_OUT – M2PA LPO Request 
Synopsis 
Request to notify M2PA of a local processor outage condition. 
Message Format 
Description 
This primitive is issued either by MTP3 or by management to notify M2PA of a local processor outage 
condition and to request that M2PA take the appropriate action to deal with such a condition. 
3.3.9 SS7_MSG_LOC_PR_OK – MTP2 LPO Recovered Request 
Synopsis 
Request to notify M2PA that the local processor outage condition has cleared. 
Message Format 
Description 
This primitive is issued either by MTP3 or by management to notify M2PA that the local processor outage 
condition has cleared and to request that M2PA take the appropriate action to deal with such a condition. 
Message Header 
Field Name Meaning 
type SS7_MSG_LOC_PR_OUT  (0xc20b) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req Sending layer’s bit set if response required. 
hclass 0 
status 0 
err_info 0 
len 0 
Message Header 
Field Name Meaning 
type SS7_MSG_LOC_PR_OK  (0xc20c) 
id l2_llid 
src Originating module_id 
dst M2PA module_id 
rsp_req Sending layer’s bit set if response required. 
hclass 0 
status 0 
err_info 0 
len 0
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Chapter 3 Message Reference 
3.4 Protocol Indications from M2PA to MTP3 
Primitive protocol indications are sent from M2PA to MTP3 in accordance with published M2PA 
recommendations. The primitive names used for the M2PA module are closely aligned with the terminology 
used in ITU-T Recommendation Q.703. 
Note: This section of the manual is applicable only to users intending to write or interface to their own 
SCTP implementation. When using the Dialogic® SS7 protocols SCTP module, this interface is 
already implemented by the SCTP module. 
The list of protocol requests sent from M2PA to MTP3 includes: 
•API_MSG_RX_IND – Received Message Indication 
•SS7_MSG_IN_SVC – M2PA In Service Indication 
•SS7_MSG_OUT_SVC – M2PA Out of Service Indication 
•SS7_MSG_REM_PR_OUT – M2PA RPO Indication 
•SS7_MSG_REM_PR_OK – M2PA RPO Cleared Indication 
•SS7_MSG_RXD_BSNT – M2PA BSNT Indication 
•API_MSG_RTVD_MSG – M2PA Retrieved Message Indication 
•SS7_MSG_RTVL_COMPL – M2PA Retrieval Complete Indication 
•MTP_MSG_RTVL_NOT_POS – M2PA Retrieval Failure Indication 
•MTP_MSG_LINK_CONG – M2PA Link Congested Indication 
•MTP_MSG_LINK_UNCONG – M2PA Congestion Cleared Indication 
•MTP_MSG_FLUSH_ACK – M2PA Flush Acknowledgement Indication 
All primitives generated by the M2PA module are sent to the “upper” module, as defined at configuration 
time for each link. This should be set to the correct module_id for the MTP3 module. 
The hdr->id field is always set to the l3_link_id as configured for the link at configuration time. Note that 
this need not be the same as the l2_llid. The use of the l3_link_id means that it is not necessary for the 
receiving module (for example, MTP3) to examine the sending module_id from which the message was 
received. 
The MTP3 (or “upper”) module is responsible for releasing the message using the relm() library function. 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.4.1 API_MSG_RX_IND – Received Message Indication 
Synopsis 
Containing received Message Signal Unit (MSU) destined to MTP3. 
Message Format 
Parameters 
•MSU data 
MSU data in binary format commencing with the Service Indicator Octet (SIO). 
Message Header 
Field Name Meaning 
type API_MSG_RX_IND  (0x8f01) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len Number of octets in MSU 
Parameter Area 
Offset Size Name 
0 len MSU data 
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Chapter 3 Message Reference 
3.4.2 SS7_MSG_IN_SVC – M2PA In Service Indication 
Synopsis 
Indicates that the signaling link is in service. 
Message Format 
Description 
This primitive is issued by M2PA to the “upper” module to indicate the successful completion of the link 
alignment procedure. 
Note: The id field of this message (and all indications to the “upper” module) contains the l3_link_id, 
which is a configuration parameter for the link and need not be the same as the l2_llid, which is 
used in messages sent to M2PA. 
Message Header 
Field Name Meaning 
type SS7_MSG_IN_SVC  (0x8303) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 0
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.4.3 SS7_MSG_OUT_SVC – M2PA Out of Service Indication 
Synopsis 
Indicates that the signaling link has failed. 
Message Format 
Description 
This primitive is issued by M2PA to the “upper” module to indicate that the signaling link is Out of Service, 
either due to an excessive error rate or a failure to complete the alignment operation. 
3.4.4 SS7_MSG_REM_PR_OUT – M2PA RPO Indication 
Synopsis 
Indicates a Remote Processor Outage (RPO) condition. 
Message Format 
Description 
This primitive is issued by M2PA to the “upper” module to indicate that a Remote Processor Outage (RPO) 
condition has been detected. 
Message Header 
Field Name Meaning 
type SS7_MSG_OUT_SVC  (0x8304) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 0 
Message Header 
Field Name Meaning 
type SS7_MSG_REM_PR_OUT  (0x8305) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 0
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Chapter 3 Message Reference 
3.4.5 SS7_MSG_REM_PR_OK – M2PA RPO Cleared Indication 
Synopsis 
Indicates the clearing of a Remote Processor Outage (RPO) condition. 
Message Format 
Description 
This primitive is issued by M2PA to the “upper” module to indicate that a signaling link that was previously in 
the Remote Processor Outage (RPO) condition has now recovered. 
Message Header 
Field Name Meaning 
type SS7_MSG_REM_PR_OK  (0x8306) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 0
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3.4.6 SS7_MSG_RXD_BSNT – M2PA BSNT Indication 
Synopsis 
Indicates the BSNT. 
Message Format 
Parameters 
•BSNT 
Backward Sequence Number Transmitted. Set to 0x80 to indicate extended BSNT. 
•reserved 
Reserved for future use. Set to zero. 
•extended_BSNT 
Extended Backward Sequence Number Transmitted. A 32-bit value; MSB first. 
Description 
This primitive is issued by M2PA in response to a M2PA BSNT Retrieval Request. It contains the BSNT in the 
parameter area of the message. 
Message Header 
Field Name Meaning 
type SS7_MSG_RXD_BSNT  (0x8307) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 1 
Parameter Area 
Offset Size Name 
0 1 BSNT 
1 1 reserved 
2 4 extended_BSNT 
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Chapter 3 Message Reference 
3.4.7 API_MSG_RTVD_MSG – M2PA Retrieved Message Indication 
Synopsis 
Primitive issued by M2PA to MTP3 to indicate the next MSU retrieved from the transmission or retransmission 
buffer. 
Message Format 
Description 
This primitive is used to pass retrieved messages from M2PA to MTP3 to allow them to be retransmitted 
down another link. 
Parameters 
•MSU data 
MSU data in binary format commencing with the Service Indicator Octet (SIO). 
Message Header 
Field Name Meaning 
type API_MSG_RTVD_MSG  (0x8f08) 
id l2_llid 
src M2PA module_id 
dst Destination module (M2PA upper_id) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len Number of octets in MSU 
Parameter Area 
Offset Size Name 
0 len MSU data 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.4.8 SS7_MSG_RTVL_COMPL – M2PA Retrieval Complete Indication 
Synopsis 
Indicates the completion of the message retrieval procedure. 
Message Format 
Description 
This primitive is issued by M2PA to the “upper” module to indicate that any messages for retrieval have been 
conveyed using M2PA Retrieved Message Indication messages, so the retrieval procedure is complete. 
Message Header 
Field Name Meaning 
type SS7_MSG_RTVL_COMPL  (0x8309) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 0
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Chapter 3 Message Reference 
3.4.9 MTP_MSG_RTVL_NOT_POS – M2PA Retrieval Failure Indication 
Synopsis 
Indicates that it is not possible to carry out message retrieval. 
Message Format 
Description 
This primitive is issued by M2PA to the “upper” module to indicate that for some reason it is not possible to 
carry out or complete the message retrieval procedure. Any retrieved messages issued to MTP3 should 
therefore be discarded. The message is issued instead of a M2PA Retrieval Complete Indication. 
Message Header 
Field Name Meaning 
type MTP_MSG_RTVL_NOT_POS  (0x8315) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 0
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3.4.10 MTP_MSG_LINK_CONG – M2PA Link Congested Indication 
Synopsis 
Provides notification of signaling link congestion. 
Message Format 
Description 
This primitive is issued by M2PA on detection of link congestion or a change in the congestion status of a link. 
Congestion is detected when the total number of messages stored in the transmit and retransmit buffers 
exceeds a configurable congestion onset threshold. The module can be configured with either a single 
congestion threshold or multiple congestion onset thresholds. 
Parameters 
•Congestion status 
Indicates the level of congestion on the link.  
Message Header 
Field Name Meaning 
type MTP_MSG_LINK_CONG  (0x8312) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 1 
Parameter Area 
Offset Size Name 
0 1 Congestion status
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Chapter 3 Message Reference 
3.4.11 MTP_MSG_LINK_UNCONG – M2PA Congestion Cleared Indication 
Synopsis 
Provides notification of the clearing of link congestion. 
Message Format 
Description 
This primitive is issued by M2PA when a link which has been congested returns to the uncongested state. 
Message Header 
Field Name Meaning 
type MTP_MSG_LINK_UNCONG  (0x8313) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 0
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
3.4.12 MTP_MSG_FLUSH_ACK – M2PA Flush Acknowledgement Indication 
Synopsis 
Provides acknowledgement of the completion of buffer flushing. 
Message Format 
Description 
This primitive is issued by M2PA in response to an MTP_MSG_FLUSH message after all messages have been 
flushed by M2PA from the transmission and retransmission buffers. 
Message Header 
Field Name Meaning 
type MTP_MSG_FLUSH_ACK  (0x8316) 
id l3_link_id 
src M2PA module_id 
dst upper module_id (eg. MTP3) 
rsp_req 0 
hclass 0 
status 0 
err_info 0 
len 0
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Chapter 4 Non-Primitive Interface 
Chapter 4:  Non-Primitive Interface 
In addition to the primitive interface for passing protocol messages and management messages between the 
M2PA module and the user modules, the M2PA module supports a non-primitive interface for implementation 
specific functionality. 
The non-primitive interface is used by the user for configuration and diagnostic purposes and to allow M2PA 
to report protocol-based and software error events to the local system management module. 
This chapter describes the formats of all the messages used in the non-primitive interface. 
4.1 Confirmation Message Status Values 
When the M2PA module returns a confirmation message containing a status value, the status is one of the 
following: 
4.2 Non-Primitive Interface Messages 
The non-primitive interface comprises the following messages: 
•M2P_MSG_CONFIG - Configure M2PA Module 
•M2P_MSG_CNF_LINK - M2PA Link Configuration Request 
•M2P_MSG_END_LINK - M2PA Link End Request 
•M2P_MSG_TRACE_MASK - TRACE MASK Set Request 
•M2P_MSG_R_STATE - READ STATE Read Request 
•M2P_MSG_R_STATS - READ STATISTICS Read Request 
•M2P_MGT_MSG_EVENT_IND - EVENT Indication 
•M2P_MSG_ERROR_IND - ERROR Indication 
•M2P_MGT_MSG_LINK_STATE - M2PA Link STATE Indication 
Mnemonic Value Description 
none 0 Success 
M2PE_BAD_ID 1 Inappropriate or invalid id in request message 
M2PE_BAD_MSG 5 Inappropriate or unrecognized message type. 
M2PE_BAD_PARAM 6 Invalid parameters contained in message.
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
4.2.1 M2P_MSG_CONFIG – Configure M2PA Module 
Synopsis 
Configure the M2PA module for operation. 
Message Format 
Description 
This message is used to configure the M2PA module for operation. It should be the first message sent to the 
module (any message received prior to this are discarded) and should only be sent once. 
Parameters 
•mngt_mod_id 
Module identifier that defines the destination for non-link specific management indications 
•trace_mod_id 
Module identifier that defines the destination for non-link specific trace indications 
•max_links 
Maximum number of links that the module is required to handle 
•Reserved 
Should be set to zero 
Message Header 
Field Name Meaning 
type M2P_MSG_CONFIG (0x7220) 
id 0 
src Sending module ID 
dst M2PA MODULE_ID 
rsp_req Used to request a confirmation 
hclass 0 
status 0 
err_info 0 
Len 16 
Parameter Area 
Offset Size Name 
0 1 mngt_mod_id 
1 1 trace_mod_id 
2 2 max_links 
4 12 Reserved 
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Chapter 4 Non-Primitive Interface 
4.2.2 M2P_MSG_CNF_LINK – M2PA Link Configuration Request 
Synopsis 
Configures an M2PA link. 
Message Format 
Description 
This message must be sent once for each link being configured. 
Message Header 
Field Name Meaning 
type M2P_MSG_CNF_LINK (0x7221) 
id M2PA Link ID 
src Sending module ID 
dst M2PA MODULE_ID 
rsp_req Used to request a confirmation 
hclass 0 
status 0 
err_info 0 
len 60 
Parameter Area 
Offset Size Name 
0 4 options 
4 1 l3_mod_id 
5 2 l3_link_id 
7 1 sctp_mod_id 
8 2 sctp_link_id 
10 1 mngt_mod_id 
11 1 trace_mod_id 
12 2 T1 
14 2 T2 
16 2 T3 
18 2 T4n 
20 2 T4e 
22 2 T6 
24 2 T7 
26 2 co1 
28 2 co2 
30 2 co3 
32 2 ca1 
34 2 ca2 
36 2 ca3 
38 2 cd1 
40 2 cd2 
42 2 cd3 
44 16 reserved
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
Parameters 
•Options 
One of the values in the following table: 
•l3_mod_id 
Module identifier for the L3 module using this link 
•l3_link_id 
Link identifier used by the L3 module for this link 
•sctp_mod_id 
Module identifier for the SCTP module used for this link 
•sctp_link_id 
Link identified used by SCTP for this link 
•mngt_mod_id 
Module identifier for Management module for this link 
•trace_mod_id 
Module identifier for Trace module for this link 
•T1 
“Alignment Ready” timer value in the range of 40 to 50 seconds. Units are in seconds. 
•T2 
“Not Aligned” timer value in the range of 5 to 50 seconds. Units are in seconds. 
•T3 
“Aligned” timer value in the range of 1 to 2 seconds. Units are in seconds. 
•T4n 
“Normal Proving” timer value in the range of 7 to 10 seconds. Units are in seconds. 
•T4e 
“Emergency Proving” timer value in the range of 400 to 600 milliseconds. Units are in 100milliseconds. 
•T6 
“Remote Congestion” timer value in the range of 3 to 6 seconds. Units are in seconds. 
•T7 
“Excessive Delay Of Acknowledgement” timer value in the range of 0.5 to 2 seconds. Units are in 
100milliseconds. 
•co1 
Congestion onset MSU threshold 1  
•co2 
Congestion onset MSU threshold 2  
•co3 
Congestion onset MSU threshold 3  
•ca1 
Congestion abatement MSU threshold 1  
•ca2 
Congestion abatement MSU threshold 2  
•ca3 
Congestion abatement MSU threshold 3  
Option Bit Description 
M2PA_LCFG_MCONG 0 Use Multiple Congestion levels 
M2PA_LCFG_7BIT 1 Use 7-bit sequence numbers instead of default 24-bit sequence numbers. Use if MTP3 does not support Extended Changeover 
Procedures. 
M2PA_LCFG_VER_9 2 This bit enables support for Draft Version 9 of the M2PA 
Specification.  Default operation supports the RFC specification.
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Chapter 4 Non-Primitive Interface 
•cd1 
Congestion discard MSU threshold 1  
•cd2 
Congestion discard MSU threshold 2  
•cd3 
Congestion discard MSU threshold 3  
•Reserved 
Should be set to zero 
4.2.3 M2P_MSG_END_LINK – M2PA Link End Request 
Synopsis 
Ends an M2PA link. 
Message Format 
Description 
This message must be sent once for each link being ended. 
Message Header 
Field Name Meaning 
type M2P_MSG_END_LINK (0x7222) 
id M2PA Link ID 
src Sending module ID 
dst M2PA MODULE_ID 
rsp_req Used to request a confirmation 
hclass 0 
status 0 
err_info 0 
len 0
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4.2.4 M2P_MSG_TRACE_MASK – TRACE MASK Set Request 
Synopsis 
Sets trace masks on a per M2PA link basis. 
Message Format 
Description 
The M2PA module supports comprehensive tracing options on a per-link and per-primitive basis. The module 
can be configured to trace any message received or transmitted and a number of management events. This 
message is used to selectively enable tracing of events. It can be used at any time during operation and 
continues to be effective until the next TRACE MASK Set Request is received for the same link. 
Traced events are indicated to the management module using the TRACE_EV Event Indication. 
Parameters 
•op_evt_mask 
The output event mask. This is a 32-bit value with bits as described below. Once the appropriate bit is 
set, a trace message is sent to the management module whenever a message is issued by M2PA for the 
event indicated. 
Message Header 
Field Name Meaning 
type M2P_MSG_TRACE_MASK (0x7223) 
id M2PA Link ID 
src Sending module ID 
dst M2PA MODULE_ID 
rsp_req Used to request a confirmation 
hclass 0 
status 0 
err_info 0 
len 16 
Parameter Area 
Offset Size Name 
0 4 op_evt_mask 
4 4 ip_evt_mask 
8 4 mgmt_evt_mask 
12 4 reserved 
Bit Number Mnemonic Description 
0 M2POEM_SCTP_ACT_REQ ACTIVATE ASC 
1 M2POEM_SCTP_ABORT_REQ ABORT ASC 
2 M2POEM_MTP_IN_SVC_IND IN SVC 
3 M2POEM_MTP_OUT_SVC_IND OUT SVC 
4 M2POEM_MTP_RPO_IND REM PROCESSOR OUT 
5 M2POEM_MTP_RPO_OK_IND REM PROCESSOR OUT OK 
6 M2POEM_MTP_RXD_BSNT_IND RXD BSNT 
7 M2POEM_MTP_CONG_IND LINK CONG 
8 M2POEM_UNCONG_IND LINK UNCONG 
9 M2POEM_MTP_RTV_FAIL_IND RTVL FAIL 
10 M2POEM_MTP_RTV_MSG_IND RTVD MSG 
11 M2POEM_MTP_RTVLCOMP_IND RTVL COMPL
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Chapter 4 Non-Primitive Interface 
•ip_evt_mask 
The input event mask. This is a 32-bit value with bits as described below. When the appropriate bit is 
set, a trace message is sent to the management module whenever a message is issued by M2PA for the 
event indicated. 
•mgt_evt_mask 
The management event mask. This is a 32-bit value with bits as described below. When the appropriate 
bit is set, a trace message is sent to the management module whenever a message is issued by M2PA for 
the event indicated. 
12 M2POEM_SCTP_TX_REQ ASC DATA REQ 
13 M2POEM_MTP_RX_IND RX IND 
14 M2POEM_MTP_FLUSH_ACK Flush Ack 
Bit Number Mnemonic Description 
0 M2PIEM_MTP_TX_REQ Message for transmission request 
1 M2PIEM_SCTP_RX_IND Receive message Indication 
2 M2PIEM_SCTP_ACT_FAIL Activate fail 
3 M2PIEM_SCTP_ASC_STATUS ASC Status 
4 M2PIEM_SCTP_ASC_CONG ASC Cong Status 
5 M2PIEM_MTP_START_REQ Start request 
6 M2PIEM_MTP_STOP_REQ Stop request 
7 M2PIEM_MTP_EMGCY_IND Emergency indication 
8 M2PIEM_MTP_EMGCY_CLEAR_IND Emergency cleared indication 
9 M2PIEM_MTP_RTV_REQ Retrieve request 
10 M2PIEM_MTP_RTV_BSNT_REQ Retrieve BSNT 
11 M2PIEM_MTP_LPO_IND Local Processor Outage Indication 
12 M2PIEM_MTP_LPO_CEASES_IND Local Processor Outage ceases indication 
13 M2PIEM_UNEX_MSG Unexpected Message received 
14 M2PIEM_MTP_FLUSH Flush Request 
15 M2PIEM_MTP_CONTINUE Continue Request 
Bit Number Mnemonic Description 
0 M2PMEM_SCTP Report SCTP Mngt events 
1 M2PMEM_M2P Report M2PA Peer events 
2 M2PMEM_MTP Report MTP3 Mngt Events 
3 M2PMEM_STATE Report Link State Events 
4 M2PMEM_UNEX Report Unexpected Message received 
Bit Number Mnemonic Description
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
4.2.5 M2P_MSG_R_STATE – READ STATE Read Request 
Synopsis 
Reads the current internal state of an M2PA link. 
Message Format 
Description 
This message may be sent by Layer Management or other module to request the state of a particular link. 
Parameters 
•la_state 
Current Link Alignment state, which can take one of the following values: 
•tx_cong_status 
Current congestion status. This takes a non-zero value if congested. If multiple congestion levels are 
being used, then values of 1, 2 and 3 indicate the current level of congestion. 
•tx_buf_occ 
Total number of buffered MSUs 
•RPO_status 
If set, the link is currently in a Remote Processor Outage (RPO) condition. 
•LPO_status 
If set, the link is currently in a Local Processor Outage (LPO) condition. 
Message Header 
Field Name Meaning 
type M2P_MSG_R_STATE (0x6224) 
id M2PA Link id 
src Sending module ID 
dst M2PA MODULE_ID 
rsp_req Used to request a confirmation 
hclass 0 
status 0 
err_info 0 
len 16 
Parameter Area 
Offset Size Name 
0 1 la_state 
1 1 tx_cong_status 
2 2 tx_buf_occ 
4 1 RPO_status 
5 1 LPO_status 
6 1 remote_cong_status 
7 1 receive_cong_status 
8 1 emergency_status 
9 7 reserved 
Value Mnemonic Description 
1 S7S_IN_SERVICE IN SERVICE state 
2 S7S_OUT_SERVICE OUT OF SERVICE state 
3 S7S_INIT_ALIGN INITIAL ALIGNMENT state 
4 S7S_ALIGN_NOT_RDY ALIGNED NOT READY state 
5 S7S_ALIGN_READY ALIGNED READY state 
6 S7S_PROC_OUTAGE Local or Remote Processor Outage state
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Chapter 4 Non-Primitive Interface 
•remote_cong_status 
If set, the link is currently in a Remote Congestion condition. 
•receive_cong_status 
If set, the link is currently in a Receive Congestion condition. 
•emergency_status 
If set, the link is currently in Emergency Alignment mode. 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
4.2.6 M2P_MSG_R_STATS – READ STATISTICS Read Request 
Synopsis 
Read the current statistics on a particular M2PA link. 
Message Format 
Description 
This message may be sent by Layer Management or other module to read statistics for the link.  The internal 
statistics can be reset or left unchanged depending on the setting of the status field. 
Parameters 
•insvc_duration 
Duration link in service (seconds) 
•stats_duration 
Time since stats last reset (seconds) 
•align_failures 
Number of failed alignment attempts 
•txd_octets 
Number of SIF and SIO octets transmitted 
•tx_msu_count 
Number of MSU's transmitted 
•rxd_octets 
Number of SIF and SIO octets received 
•rx_msu_count 
Number of MSU's received 
•cong_count 
Number of congestion events 
Message Header 
Field Name Meaning 
type M2P_MSG_R_STATS (0x6225) 
id M2PA Link id 
src Sending module ID 
dst M2PA MODULE_ID 
rsp_req Used to request a confirmation 
hclass 0 
status 0 = Leave statistics unchanged 
1 = Reset statistics after reading 
err_info 0 
len 60 
Parameter Area 
Offset Size Name 
0 4 insvc_duration 
4 4 stats_duration 
8 2 align_failures 
10 4 txd_octets 
14 4 tx_msu_count 
18 4 rxd_octets 
22 4 rx_msu_count 
26 4 cong_count 
30 4 cong_duration 
34 4 discard_count 
38 4 discard_events 
42 18 reserved
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Chapter 4 Non-Primitive Interface 
•cong_duration 
Duration of link congestion (seconds) 
•discard_count 
Number of MSU's discarded due to congestion 
•discard_events 
Number of congestion events leading to MSU discard 
•reserved 
Reserved for future use. Should be set to zero. 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
4.2.7 M2P_MGT_MSG_EVENT_IND – EVENT Indication 
Synopsis 
Provides an indication of events occurring within the M2PA module. 
Message Format 
Description 
This message is issued by M2PA to the management module (as configured in the configuration message) to 
advise of events occurring within M2PA. Specific indications are only issued if the corresponding EVENT bit of 
the management Trace event mask is set. 
The EVENT_CODE and id field are coded as shown in the following table: 
Message Header 
Field Name Meaning 
Type M2P_MGT_MSG_EVENT_IND (0x0227) 
Id ID (see table below) 
Src M2P module id 
Dst Management module id 
rsp_req Used to request a confirmation 
hclass 0 
status Event Code (see table below) 
err_info 0 
len 0 
Value Mnemonic id Description 
1 M2P_EVT_MSG_TYPE 0 Unknown Message Type Received 
2 M2P_EVT_UNEX_EVENT l2_llid An unexpected event has been received on this link 
3 M2P_EVT_SCTP_BAD_LEN l2_llid An SCTP message has been received with an invalid 
length 
4 M2P_EVT_SCTP_BAD_ASC_ID 0 An SCTP message has been received with an invalid 
Association ID 
5 M2P_EVT_MTP_BAD_LINK_ID l2_llid A User message has been received with an invalid link id 
6 M2P_EVT_SCTP_ASC_EST l2_llid SCTP Association has entered the Established State 
7 M2P_EVT_SCTP_ASC_FAIL l2_llid SCTP Association has entered the Failed State 
8 M2P_EVT_SCTP_ASC_CONG l2_llid SCTP Association has entered the Congested State 
9 M2P_EVT_UNEX_PEER l2_llid An Unexpected Message has been received from the 
Peer M2PA 
10 M2P_EVT_UNEX_SCTP l2_llid An Unexpected Message has been received from SCTP 
11 M2P_EVT_UNEX_MTP l2_llid An Unexpected Message has been received from MTP 
12 M2P_EVT_UNEX_MGT l2_llid An Unexpected Message has been received from 
Management 
13 M2P_EVT_MTP_EMGCY l2_llid MTP has requested the Link use emergency proving 
14 M2P_EVT_MTP_EMGCY_CLR l2_llid MTP requests the link use normal proving 
15 M2P_EVT_M2P_BAD_FSNR l2_llid A message has been received with an invalid FSN 
16 M2P_EVT_M2P_BAD_BSNR l2_llid A message has been received with an invalid BSN 
17 M2P_EVT_RTV_FAIL l2_llid A Retrieval Attempt has failed 
18 M2P_EVT_CONG_DISCARD l2_llid Excess Congestion has resulted in the discard of a 
message 
19 M2P_EVT_MTP_FMT_ERROR l2_llid A badly formatted message has been received from MTP 
20 M2P_EVT_SCTP_FMT_ERROR l2_llid A badly formatted message has been received from 
SCTP
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Chapter 4 Non-Primitive Interface 
4.2.8 M2P_MSG_ERROR_IND – ERROR Indication 
Synopsis 
Notifies system management of various software errors occurring within the module which under normal 
operating conditions should not occur. 
Message Format 
Description 
This message is issued by M2PA to the management module (as configured in the configuration message) to 
advise of general software events. These events may be due to lack of system resources or errors within the 
software. Individual indications are issued dependant on the bits set in the management event trace mask. 
The ERROR_CODE, id field, Parameter 1 and Parameter 2 definitions are as shown in the following table: 
Message Header 
Field Name Meaning 
type M2P_MSG_ERROR_IND (0x0228) 
id ID (see below) 
src M2P module id 
dst Management module id 
rsp_req 0 
hclass 0 
status ERROR CODE (see below) 
err_info 0 
len 4 
Parameter Area 
Offset Size Name 
0 2 Parameter 1 (see below) 
2 2 Parameter 2 (see below) 
Value Mnemonic id Parameter 1 Parameter 2 Description 
0 M2P_ERR_TIM_START link id timer_type timer_id Failed to start Timer 
1 M2P_ERR_LNK_END link id asc_id 0 Failed to end link 
2 M2P_ERR_UNEX_INT_EVT link id state 
machine id state id Unexpected event generated internally 
3 M2P_ERR_BUFF_FAIL link id sequence 
number 0 Failed to buffer MSU
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4.2.9 M2P_MGT_MSG_LINK_STATE – M2PA Link STATE Indication 
Synopsis 
Informs Management of changes in the current internal state of the M2PA link. 
Message Format 
Description 
This primitive is used by M2PA to indicate to local management changes of state within the Link State Control 
function. These indications are only given if the S7_STATUS bit of the management event trace mask is set. 
Note: This message is intended for diagnostic and maintenance purposes and does not form part of the 
protocol specified primitives. 
The LINK STATE is coded as shown in the following table: 
Message Header 
Field Name Meaning 
type M2P_MGT_MSG_LINK_STATE (0x0226) 
id M2PA Link id 
src M2PA module id 
dst Management module id 
rsp_req 0 
hclass 0 
status LINK STATE (see below) 
err_info Timestamp 
len 0 
Value Mnemonic Description 
1 S7S_IN_SERVICE Entered IN SERVICE state 
2 S7S_OUT_SERVICE Entered OUT OF SERVICE state 
3 S7S_INIT_ALIGN Entered INITIAL ALIGNMENT state 
4 S7S_ALIGN_NOT_RDY Entered ALIGNED NOT READY state 
5 S7S_ALIGN_READY Entered ALIGNED READY state 
6 S7S_PROC_OUTAGE Entered PROCESSOR OUTAGE state
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Chapter 5 Typical Configuration Values 
Chapter 5:  Typical Configuration Values 
Table1 gives typical values to be used in the configuration messages for correct operation of M2PA to quickly 
get the system up and running. 
To ensure the appropriate values are being used for a specific installation, refer to the detailed message 
definitions in this manual. 
Table 1. Typical Configuration Values 
Parameter Typical Setting (for ITU-T operation) 
options 0x0000 
upper_id 0x22 (MTP3 module) 
lower_id 0x00 
mgmt_id 0x8e (Management module) 
monitor_id 0 
max_SIF_len 272 
cong_onset 50 
cong_abate 20 
pcr_n1 0 
pcr_n2 0 
rtv_attempts 4 
t1 450 (giving T1 = 45 seconds) 
t2 300 (giving T2 = 30 seconds) 
t3 12 (giving T3 = 1.2 seconds) 
t4n 82 (giving T4 
N = 8.3 seconds) 
t4e 5 (giving T4E = 0.5 seconds) 
t5 1 (giving T5 = 100 ms) 
t6 55 (giving T6 = 5.5 seconds) 
t7 15 (giving T7 = 1.5 seconds) 
t_suerm 10 
t_rtv 1 
cong_discard 128 
l3_link_id Set to the MTP3 link_id 
co1 40 
co2 60 
co3 80 
ca1 30 
ca2 50 
ca3 70 
cd1 45 
cd2 65 
cd3 80 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
Chapter 6:  Message Types 
6.1 Message Type Table 
Table2 lists, by message type, all the new messages defined in this manual. 
Note: The message type for the confirmation message is set as described in the System Software 
Environment Programmer's Manual, in the paragraph describing the rsp_req field. 
Table 2. Message Types 
Message Type Mnemonic Description 
0x0226 M2P_MGT_MSG_LINK_STATE M2PA Link STATE Indication 
0x0227 M2P_MGT_MSG_EVENT_IND EVENT Indication 
0x0228 M2P_MSG_ERROR_IND ERROR Indication 
0x6224 M2P_MSG_R_STATE READ STATE Read Request 
0x6225 M2P_MSG_R_STATS READ STATISTICS Read Request 
0x7220 M2P_MSG_CONFIG Configure M2PA Module 
0x7221 M2P_MSG_CNF_LINK M2PA Link Configuration Request 
0x7222 M2P_MSG_END_LINK M2PA Link End Request 
0x7223 M2P_MSG_TRACE_MASK TRACE MASK Set Request 
0x2224 - Confirm Link State Request 
0x2225 - Confirm Link Stats Request 
0x3220 - Confirm M2PA Module Configuration 
0x3221 - Confirm M2PA Link Configuration Request 
0x3222 - Confirm M2PA Link End Request 
0x3223 - Confirm M2PA Link Trace Mask Set Request
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Chapter 7 Timer Services 
Chapter 7:  Timer Services 
7.1 Introduction 
The notion of time in the M2PA module is based on a periodic timer tick received from the timer module 
every 100 milliseconds. This “tick” is used to run all M2PA protocol timers. This chapter details the message 
formats that are used by the M2PA module to control timer services. 
Timer messages include: 
•KEEP_TIME - Keep Time 
•TM_EXP - Timer Expiry 
7.1.1 KEEP_TIME – Keep Time 
Synopsis 
Message sent to request the timer module to issue a periodic timer tick (TM_EXP) message to the M2PA 
module. 
Message Format 
Parameters 
•reserved 
Should be set to zero if issued by the user and is discarded when received by the timer module. 
•resolution 
The number of operating system ticks between timer expiry messages being issued to the M2PA module. 
Message Header 
Field Name Meaning 
type KEEP_TIME (0x7006) 
id 0 
src Sending module’s ID 
dst Timer module ID 
rsp_req 0 
class 0 
status 0 
err_info 0 
len 6 
Parameter Area 
Offset Size Name 
0 4 Reserved 
4 2 resolution
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
7.1.2 TM_EXP – Timer Expiry 
Synopsis 
Periodic timer tick message issued by the timer module. 
Message Format 
Parameters 
•reserved 
Must be set to zero. 
Message Header 
Field Name Meaning 
type TM_EXP (0xc002) 
id index of timer in table 
src Timer module ID 
dst Destination module ID 
rsp_req 0 
class 0 
status 0 
err_info 0 
len 4 
Parameter Area 
Offset Size Name 
0 4 reserved 
56 
Appendix A Network Address Representation 
Appendix A: Network Address Representation 
The SCTP module is designed to facilitate future support for IP V6 addresses. Currently only IPV4 addresses 
are supported, but the interface to the module is designed to accommodate V6 addresses in the future. 
A.1 Network Address Structure for an Invalid Address 
An invalid or “not present” network address is represented in the following way: 
•Address Type - ADR_NONE 
•Address Value - Undefined 
A.2 Network Address Structure for Internet Protocol Version 4 
IPV4 network addresses are represented in the following way: 
•Address Type - ADR_IPV4 
•Address Value - 16 octets containing the following: 
—Octet 0 - MSB of network address 
—... 
—Octet 3 - LSB of network address 
—Octet 4 - undefined 
—... 
—Octet 15 - undefined 
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Dialogic® SS7 Protocols M2PA Programmer’s Manual Issue 3 
Glossary 
BSNT Backward Sequence Number Transmitted 
FSNC Forward Sequence Number Confirmed 
M2PA An implementation of the IETF SIGTRAN, SS7 MTP2-User Peer-to-Peer Adaptation Layer 
(M2PA). 
MTP2 Message Transfer Part Level 2. An SS7 stack layer that provides link-layer functionality. 
Ensures that two end points of a signaling link can reliably exchange signaling messages. 
It provides error checking, flow control and sequence checking. 
MTP3 Message Transfer Part Level 3. An SS7 stack layer that provides network-layer 
functionality. Ensures that messages can be delivered between signaling points across 
the SS7 network regardless of whether the signaling points are directly connected. It 
provides node addressing, routing, alternate routing and congestion control. 
LSSU Link Status Signal Units. A signal unit that provides link status indications (for example, 
normal, out of alignment, out of service, emergency status) to the remote end of the 
signaling link. 
MSU Message Signal Unit. A data unit that carries signaling information for call control, 
transaction processing, network management and maintenance. Typically, the MSU is 
carried in the Signaling Information Field (SIF) of SS7 messages. 
PPID Payload Processor Identifier 
Q.703 ITU-T Recommendation Q.703, Message Transfer Part Layer 2 
RPO Remote Processor Outage 
SCTP Stream Control Transmission Protocol 
SIF Signaling Information Field 
SIGTRAN The IETF Signaling Transport Group 
SIO Service Information Octet 
SS7 Signaling System Number 7 
SSF Sub-Service Field 
SU Signal Unit 
58 
Index 
Index 
C 
configuration 
typical values 52 
D 
documentation 
related information 5 
I 
indication messages 
M2PA to MTP3 26 
SCTP to M2PA 13 
M 
M2PA 
features 6 
overview 6 
M2PA link 
configuration request 40 
end request 42 
reading statistics 47 
reading the state 45 
setting the trace mask 43 
M2PA module 
configuration of 39 
providing notification of errors 50 
providing notification of events 49 
providing notification of M2PA link state change 51 
M2PA to MTP3 indications 
M2PA BSNT Indication 31 
M2PA Congestion Cleared Indication 36 
M2PA Flush Acknowledgement Indication 37 
M2PA In Service Indication 28 
M2PA Link Congested Indication 35 
M2PA Out of Service Indication 29 
M2PA Retrieval Complete Indication 33 
M2PA Retrieval Failure Indication 34 
M2PA Retrieved Message Indication 32 
M2PA RPO Cleared Indication 30 
M2PA RPO Indication 29 
Received Message Indication 27 
M2PA to SCTP requests 
SCTP Association Abort Request 11 
SCTP Association Activate Request 9 
SCTP Association Data Transfer Request 12 
SCTP Association Shutdown Request 10 
message interface 
non-primitive 38 
primitive 8 
MP2A 
definition of 5 
MTP3 to M2PA requests 
M2PA BSNT Retrieval Request 23 
M2PA Cancel Emergency Request 22 
M2PA Link Start Request 20 
M2PA Link Stop Request 21 
M2PA LPO Recovered Request 25 
M2PA LPO Request 25 
M2PA Retrieval Request 24 
M2PA Set Emergency Request 22 
Message for Transmission Request 19 
R 
request messages 
M2PA to SCTP 8 
MTP3 to M2PA 18 
S 
SCTP to M2PA indications 
SCTP Association Congestion Status 17 
SCTP Association Data Transfer Indication 15 
SCTP Association Network Status 16 
SCTP Association Status Change 14