M3UA


M3UA is a communication protocol of the SIGTRAN family, used in telephone networks to carry signaling over Internet Protocol. M3UA enables the SS7 protocol's User Parts to run over virtually any network technology breaking its limitation to telephony equipment like T-carrier, E-carrier or Asynchronous transfer mode, which highly improves scalability of the signaling networks.
M3UA stands for MTP Level 3 User Adaptation Layer as defined by the IETF SIGTRAN working group in . Like other adaptation protocols, M3UA uses service of SCTP to transmit messages between its network elements.

Implementation scheme

Typical scheme


________ _________ __________ 
 MTP3
point-code common point-code
 PC1  PC2

Use SGW as STP

Several AS owns PC itself and uses SGW as STP.

________ _____________ ___________ 
 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, some others are recommended.

Additional info

An open implementation of the M3UA standard can be found at OpenSS7's web site.
Wireshark is shipped with a dissector for M3UA, sample packets can be found in Wireshark's wiki page, which shows ISUP Packet samples.