Telecommunications Signaling
Highlights the conventions of signalling systems and provides a detailed assessment of their architecture.
TABLE OF CONTENTS Telecommunications Signaling
Chapter 17: Interworking of CCS Systems
17.1 Introduction
Previous chapters have described the architecture, formats and procedures of the main CCS systems, namely CCSS7, DSS1 and DSS2. There are many principles that are common to the CCS systems. However, Chapter 2 explains that, because DSS1 and DSS2 are optimised for use in the access network and CCSS7 is optimised for inter-nodal use, the two types of system are different when considered at a detailed level. This chapter establishes the principles of interworking CCS systems by describing the interworking1 of CCSS7 and DSS1. Examples of interworking for basic and more complex calls are given.
17.2 Interworking Principles
17.2.1 Constituents
Signalling facilitates the transfer of information (a) between users, ( b) between users and nodes in the network and ( c) between nodes in the network. In this context, users and nodes can be regarded as 'entities' wishing to communicate.
Chapter 3 describes the architecture of modern CCS systems and, in particular, the tiered structure adopted for specification purposes. The structure allows CCS systems to be defined in terms of:
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the primitives transferred between adjacent tiers within an entity, reflecting the services offered by one tier to another tier;
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the procedures used between corresponding tiers in different entities to transfer information;
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the formats of messages exchanged between corresponding tiers in different entities.
These constituents are illustrated in Fig. 17.1.
Figure 17.1: Constituents of Interworking
Provided there is an understanding of the relationship between the tiers in different signalling systems, the structure can be used as a...
Copyright The Institution of Electrical Engineers 1999 under license agreement with Books24x7
