System information

FCD 901 48

Issue R2A, 07.2009

XMP1 Release 5.5 System Description

2 Mbit/s Connections

Aastra Proprietary Information Page 2-29

2.4 2 Mbit/s Connections

The structure of a PCM network is defined by the nodes and the 2 Mbit/s

connections between the individual nodes. Each node available in the

network is assigned a hardware number. This hardware number permits the

node to be addressed within the network. The 2 Mbit/s connections are

switched between two ports.

Figure 2.13: Node links

2.4.1 Setting options for the 2 Mbit/s connection

Signalling channel in time slot 16

If a 2 Mbit/s connection is used to transmit voice signals, time slot 16 of the

pulse frame must be defined as signalling channel.

If only data are transmitted, time slot 16 can be used as additional data

channel 31.

CRC4 procedure

In addition to the frame synchronization process, the CRC4 procedure can

be applied to ensure frame synchronization. Also see Section 2.2.2, CRC4

procedure .

Processing service digits

The system channel is composed of the signal used to control clock priority

and the signal used for communication between the nodes and network

management system, i.e. the ECC8. In normal cases of application, the

system channel is transmitted in the Sa bits carried in time slot TS0 of the

PCM30 frame.

— The signal used to control the clock priority in the XMP1 network is

transmitted in the Sa5 bit of the system channel.

Node 1 Node 2

PO4

Card slot 15

Card slot 5

1st port 2nd port

2 Mbit/s link

Node no.: 1

Card slot: 15

Port no.: 3

Node no.: 2

Card slot: 5

Port no.: 4

2 Mbit/s link