M3UA is a

communication protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics (computer scien ...

of the

SIGTRAN SIGTRAN is the name, derived from ''signaling transport'', of the former Internet Task Force (I) working group that produced specifications for a family of protocols that provide reliable datagram service and user layer adaptations for Signaling ...

family, used in

telephone network A telephone network is a telecommunications network that connects telephones, which allows telephone calls between two or more parties, as well as newer features such as fax and internet. The idea was revolutionized in the 1920s, as more and more ...

s to carry

signaling In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...

over

Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP h ...

(IP). M3UA enables the SS7 protocol's User Parts (e.g. ISUP, SCCP and TUP) to run over virtually any network technology breaking its limitation to telephony equipment like

T-carrier The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls. The first version, the Transmission System 1 (T1), was introduced in 1962 in the Bell System ...

E-carrier The E-carrier is a member of the series of carrier systems developed for digital transmission of many simultaneous telephone calls by time-division multiplexing. The European Conference of Postal and Telecommunications Administrations (CEPT) orig ...

Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by American National Standards Institute (ANSI) and ITU-T (formerly CCITT) for digital transmission of multiple types of traffic. ATM was developed to meet the needs of ...

(ATM), which highly improves

scalability Scalability is the property of a system to handle a growing amount of work by adding resources to the system. In an economic context, a scalable business model implies that a company can increase sales given increased resources. For example, a ...

of the signaling networks. M3UA stands for MTP Level 3 (MTP3) User Adaptation Layer as defined by the

IETF The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements and a ...

working group in (which replaces and supersedes ). Like other adaptation protocols, M3UA uses service of

SCTP The Stream Control Transmission Protocol (SCTP) is a computer networking communications protocol in the transport layer of the Internet protocol suite. Originally intended for Signaling System 7 (SS7) message transport in telecommunication, the p ...

to transmit messages between its network elements.

Implementation scheme

Image:M3UA-scheme.svg, 404x404px, M3UA: Transmitting MTP-3 messages: on the left is the

TDM TDM may refer to: * ''TDM (film), TDM'', a 2023 Indian Marathi language, Marathi comedy film * TDM (Macau) (), a Macanese radio and television network * The Yamaha TDM, a motorcycle model * Target Disk Mode, a boot mode on certain Macintosh compute ...

-network for SS7. On the right is the IP-network with SIGTRAN as a transport., center rect 1 1 100 72 Point code rect 1 90 593 123 ISUP rect 1 123 593 160 SCCP rect 1 160 100 232 MTP-3 rect 1 232 100 445 MTP-2 rect 1 445 100 515 MTP-1 rect 248 1 347 72 Point code rect 199 160 296 232 MTP-3 rect 199 232 296 445 MTP-2 rect 199 445 296 515 MTP-1 rect 298 160 397 232

M3UA M3UA is a communication protocol of the SIGTRAN family, used in telephone networks to carry signaling over Internet Protocol (IP). M3UA enables the SS7 protocol's User Parts (e.g. ISUP, SCCP and TUP) to run over virtually any network technol ...

rect 298 232 397 302

rect 298 302 397 372 IP rect 298 372 397 445 L2 rect 298 445 397 515 L1 rect 493 1 593 72 Point code rect 493 160 593 232

rect 493 232 593 302

rect 493 302 593 372 IP rect 493 372 593 445 L2 rect 493 445 593 515 L1 rect 15 522 85 565

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Wo ...

rect 248 522 347 565

Signaling gateway A signaling gateway is a network component responsible for transferring signaling messages (i.e. information related to call establishment, billing, location, short messages, address conversion, and other services) between Common Channel Signalin ...

rect 493 522 580 565

Media Gateway Controller The media gateway control protocol architecture is a methodology of providing telecommunication services using decomposed multimedia gateways for transmitting telephone calls between an Internet Protocol network and traditional analog facilities of ...

Typical scheme

________                   _________                __________ 
,       ,                    ,        ,                 ,      MGC, 
,   SP  , <----------------->,   SGW  , <---------------, -->(AS) , 
, ______,    SS7 network     , _______,    IP network   , ________, 
  MTP3
point-code                         common point-code
   PC1                                    PC2

Use SGW as STP

Several AS owns PC itself and uses SGW as STP (transit pointcode).

________                 _____________               ___________ 
,       ,                  ,     SGW    ,                ,       MGC, 
,       ,                  ,            ,  /-------------, -->(AS)  ,  point-code PC3
,   SP  , <----------------, -->(STP)<--, -              ,          , 
,       ,                  ,            ,  \-------------, -->(AS)  ,  point-code PC4
, ______,   SS7 network    , ___________,    IP network  , _________, 
  MTP3                    point-code
point-code                   PC2                         
   PC1

Protocol

M3UA uses a complex state machine to manage and indicate states it's running. Several M3UA messages are mandatory to make a M3UA association or peering fully functional (ASP UP, ASP UP Acknowledge, ASP Active, ASP Active Acknowledge), some others are recommended (Notify, Destination Audits (DAUD)).

Additional info

An open implementation of the M3UA standard can be found at OpenSS7's web site.

Wireshark Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education. Originally named Ethereal, the project was renamed Wireshark in May 2006 d ...

is shipped with a dissector for M3UA, sample packets can be found in Wireshark's wiki page, which shows ISUP Packet samples (including M3UAWireshark wiki page
/ref>).

References

{{Reflist

External links

M3UA Library
Internet protocols Internet Standards Signaling System 7