Objectives.. •Definition. •INBAND & OUTOF BAND signaling •CAS&ISDN at a Glance •SS7 Protocol Stack&Standerds •C7 Layer concepts •Signaling Units. It consists of signaling points or signaling nodes connected with the signaling links. The CCS7 network has four distinct signaling points. Service signaling points. Ccs7. 1. General Telecom Common Channel Signalling System #7 Handout VHBE Ed. 07; 2. Status Released Change Note.
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The CCS7 network is a logically separate network within a telecommunication network. It consists of signaling points or signalping nodes connected with the signaling links. The CCS7 network has four distinct signaling points.
Service signaling points SSPs are network nodes that generate signaling messages to transfer call- or transaction- non-call- related information between different CCS7 nodes. In wireline networks, a local switch may have Cc7s capabilities.
Signaling transfer points STPs are network nodes that relay signaling information from one signaling node to another.
Signaling links interconnect two signaling points. A signaling linkset is made up of multiple signaling links. It is recommended to have at least two signaling links in a linkset for reliability purposes.
A linkset can have a maximum of 32 links. A route is defined as a collection of links between originating and terminating SPs via intermediate nodes.
There may be several routes that a message can traverse between the originating and terminating SP. These signaling routes are collectively called a signaling routeset.
Figure shows a simplified CCS7 signaling network architecture.
CCS7 Network Architecture
As we will learn later in this topic, the CCS7 protocol has a built-in error recovery sifnalling to ensure reliable transfer of signaling messages. In addition, redundant links are provided to transfer the signaling messages using alternate routes in case of link failure. CCS7 has a layered protocol architecture, as shown in Figure The protocol stack consists of four levels. It defines the physical signallling electrical characteristics of the signaling link connecting two signaling nodes.
OVERVIEW OF CCS7 SIGNALLING
It is responsible for error-free transmission of messages between two adjacent signaling nodes. At Level 4, there are several user parts or application parts. Signaling control points SCPs are nodes that contain databases that enable enhanced services.