Issue 2 - 07/00 A3-11
Appendix 3—Introduction to ISDN
Layer 3
Layer 3 routes messages to their destination. The diagram
below shows the structure of the Layer 3 signalling messages.
Protocol Discriminator Identifies the protocol.
Call Reference Value Identifies the call with which a
message is to be associated.
Message Type Describes the intention of the
message: CONNECT, SETUP, etc.
Information Elements A number of these may be included.
Their number and content depend
upon the message type.
Protocols
A protocol is an agreed set of rules for carrying out a particular
function such as the exchange of information.
ETSI
The standard ISDN protocol used within Europe. Based on
ITU-T specifications Q.921 and Q.931.
1TR6
The national protocol for the ISDN environment in Germany.
It is also often used in private networks utilising equipment of
German origin.
To Next Page
Loading...
Need help?
General
