PEB2085 SIEMENS [Siemens Semiconductor Group], PEB2085 Datasheet - Page 107

• Manufacturer Part Number: PEB2085
• Description: ISDN SubscribernAccess Controller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

2.8
LAPD, layer 2 of the D-channel protocol (CCITT I.441) includes functions for:
– Provision of one or more data link connections on a D channel (multiple LAP).
– HDLC-framing
– Application of a balanced class of procedure in point-multipoint configuration.
The simplified block diagram in figure 56 shows the functional blocks of the ISAC-S which
support the LAPD protocol.
Figure 56
D-Channel Processing of the ISAC
Semiconductor Group
Discrimination between the data link connections is performed by means of a data link
connection identifier (DLCI = SAPI + TEI)
Layer 1
Layer
Upper
Layers
2
Layer-2 Functions for the ISDN Basic Access
2 x 32 byte
Receiver
R-FIFO
HDLC
µ
Transmitter
2 x 32 byte
µC-System
P-Interface
X-FIFO
HDLC
Command
®
Controller
Controller
Registers
-S
Status
LAPD
FIFO
107
IOM
R
Functional Description
Functions
Layer-1
S(D-Channel)
ITS00861