Isdn Configuration Concept; Isdn Layering; Isdn Layering Model - Patton electronics SmartWare R.3.20 Software Configuration Manual

SmartWare Software Configuration Guide
IMPORTANT
ISDN Configuration Concept

ISDN Layering

ISDN consists of 3 layers. Each layer has its own parameters that need to be configured.
• Layer 1, often called the physical layer, is responsible to transport single bits between two systems. Layer 1
does not guarantee that a message can be transmitted without errors.
Parameters: Clock mode, line codes.
• Layer 2 allows a station to reliably send messages to another station using the D channel. Layer 2 imple-
ments flow control, error detection and correction (retransmission) as well as addressing mechanism to
direct messages to individual devices.
Parameters: point-to-point or point-to-multipoint mode, network/user side, permanent layer 2 enabled.
• Layer 3 does send and receive application level messages (i.e. call control). It cares for sending broadcast
messages and collecting the individual results of the attached devices. It also handles the assignment of the B
channels.
Parameters: network/user side, protocol (i.e. DSS1), maximum number of channels.
The layered model of ISDN is reflected in the configuration by the use of different modes for each layer. The
layers are connected by using encapsulations and bindings. The encapsulation defines what the next higher
layer protocol will be. On the topmost layer, the binding finally selects a logical interface to connect the
port to.

ISDN Configuration Concept

Connector pin-out and short circuits—Some of the Smart-
Node ISDN BRI ports are configurable to operate as network or
terminal ports. The pin-out of the sockets is switched according to
this configuration. Wrong port configurations, wrong cabling or
wrong connections to neighboring equipment can lead to short
circuits in the BRI line powering. Refer to the HW installation
guide and the port configuration sections below to avoid miscon-
figurations.
Call Control
Layer 3 (Q.931)
Layer 2 (Q.921)
Layer 1
Phys. Port
Figure 74. ISDN layering model
35 • ISDN port configuration
Encapsulation: cc-
Bind: <call control interface>
Encapsulation: q931
Encapsulation: q921
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