Signaling protocol

Signaling protocols are protocols that are used for signaling.

Telecommunications networks

In the telecommunications sector, a distinction signaling protocols (English: signaling protocols ), formerly known as signaling or telecommunication method of signaling systems (English: signaling systems). Protocols, procedural rules, which encodes control messages are decoded and interpreted. Several protocols are arranged in so-called layers (see ISO / OSI reference model), are used to cover a power requirement, and form a signaling system. Protocols are generally subject to a standardization in order to unite various telecommunications products manufacturers. The standardized in international and national bodies protocols are compared with proprietary protocols that are not subject to standardization and are mostly published by individual manufacturers.

A well-known example of a signaling system is the Signaling System 7 A signaling protocol is ISUP or SCCP would, for example.

Types of signaling protocols

Transmission of the signaling information

In principle, the following variants of the transmission of signaling information can be distinguished:

  • User-channel signaling ( in - band signaling ) Here, the signaling information is transmitted in the payload channel with. Applied for example in analog telephones and (formerly ) for analog telephone networks. User-channel signaling method is also referred to as channel-associated signaling (English channel- associated signaling )
  • Co-channel signaling ( out-of- band signaling ) Here, the signaling information is sent in a separate signaling channel is assigned to the traffic channel directly. Applied, for example, with ISDN phones and digital telephone networks.
  • Common channel signaling Here, the signaling information for a greater number of useful channels that may be distributed over several trunk group is transmitted in a shared signaling channel. This is the Signaling System No.. 7 the case.

Function in the telephone network

We distinguish the types of signaling also according to their function in the telephone network, whether they interfaces between network nodes (NNI ) or between network nodes and connections define (UNI).

  • Examples of signaling protocols at user interfaces ( UNI): Tone dialing (for analog phones now commonplace )
  • Pulse dialing ( older signaling protocol for analog phones )
  • Diode -earth method ( older signaling protocol for analog phones especially on a PABX )
  • ITU- T Q.931 DSS1 the (now common practice for ISDN telephones and PBXs )
  • FTZ 1 TR 6 ( older signaling protocol for ISDN telephones ).
  • Signalling System No.. 7 (today, almost without exception used )
  • Signalling System No.. 5 ( precursor of number 7, never introduced in Germany )
  • Pulse dialing ( outdated procedures for telephone networks in Europe no longer used).

Of transmission of the signaling information

A further distinction is obtained for analogue and digital transmission of the signaling protocols. Although analog switching technology and their analog signaling between switching nodes are no longer used today in Europe, they used to play for the first construction of a global phone network an important role. Signs, or signals are, in principle, always digitally coded, do so at a particular processing level discrete information. However, the difference in the physical layer of transmission, that was used in the older analog technologies to distinguish the characters. You are not binary coded here, as in the so-called digital signaling, but their distinction is based for example on the length of a signal, see pulse signal process 50 ( IMC 50) or the pitch of a transmitted sound such as in the multi-frequency dialing.

  • Examples of analog Signalisierunsprotokolle: IKZ 50
  • Pulse dialing
  • Multifrequency
  • Signalling System No.. 7,
  • DSS1 ( ITU- T Q.931)

Packet-switched method

In modern packet-switched networks and signaling information over IP connections are made. An example is

  • SIGTRAN (Signaling System No.. 7 over IP)

Internet

In Internet signaling is used to configure Middleboxes or end node for the creation of permanent (hard states ) or volatile (soft states ) states. Middleboxes are nodes which are positioned between a transmitter and receiver, and change in addition to the forwarding of data packets or evaluate this.

Examples of signaling protocols are protocols for

In the IETF Working Group Next Steps in Signaling a generic protocol framework for signaling was developed. For this purpose originated RFCs for

  • QoS signaling through the QoS NSIS Signaling Layer Protocol (RFC 5974)
  • Network Address Translation ( NAT) - NAT and firewall configuration through / FW NSIS Signaling Layer Protocol (RFC 5973 )
Signalling System No. 7 Digital Subscriber System No. 1 Network to Network Interface Skinny Call Control Protocol
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