Message Transfer Part

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The Message Transfer Part ( MTP ) is part of SS7 signaling and describes how signaling information is transmitted. It is used for communication in the public telephone network ( PSTN ). MTP is responsible for the transport of SS7 messages between communication partners.

A distinction is made between three MTP levels, which can be incorporated into the OSI model . MTP level 1 is the physical layer, MTP level 2 is the data layer and MTP level 3 is the network layer.

  • MTP Level 1 defines the physical, electrical and functional parameters for a signaling route. This includes specifications such as clock rate, voltages, coding methods and the dimensions and shape of the connectors . Interfaces that correspond to recommendations V.35 or G.703 are common. Level 1 represents the bit transmission layer for a signaling link, which in a digital network usually consists of a 64 kbit / s channel. However, analog channels that are operated with a modem can also be used.
  • MTP Level 2 defines the procedures for an error-free exchange of messages over a signaling path. This includes functions to activate or terminate the communication link, to check for errors and to correct them if necessary. The messages are separated from one another by flags. Level 2 is similar in structure to the frequently used HDLC procedure , but with some additional functions.
  • MTP Level 3 defines the interaction of several individual signaling links. All aspects that are common at the logical level for the exchange of messages between two signaling points over several signaling paths are regulated. This includes the forwarding of incoming messages to the desired signaling path. The separation of these functions in a separate level 3 also serves the management of the signaling network: Signaling routes can be added, or in the event of an error it can be switched to an alternative route without having to change the configuration at higher, more abstract levels.

SS7-MTP1-MTP3.png

literature

  • Otfried Georg: Telecommunication technology. 2nd revised edition, Springer Verlag, Berlin Heidelberg 2000, ISBN 978-3-642-63105-4 .
  • Firoz Kaderali: Digital Communication Technology II. Friedrich Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig 1995, ISBN 978-3-528-06485-3 .
  • Wolf-Dieter Haaß: Handbook of the communication networks. Springer Verlag, Berlin / Heidelberg 1997, ISBN 978-3-642-63825-1 .
  • PR Gerke: New communication networks. Springer Verlag, Berlin / Heidelberg 1982, ISBN 978-3-642-93207-6 .

See also

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