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PEB 20550
PEF 20550
Overview
Semiconductor Group
31
01.96
1.6.1.3 Decentralized D-Channel Processing, Dedicated HDLC-Controller per
Subscriber
In this configuration IDECs (ISDN D-channel exchange controller, PEB 2075) handle the
layer-2 functions for signaling and data packets in the D-channel. The extracted data is
separated and sent via the
μ
P and the SACCO to the system interface. In this
configuration signaling data is transferred on the PCM-highway, for packet data a
dedicated bus system with collision resolution is used.
Figure 11
Line Card Architecture for Completely Decentralized D-Channel Processing
1.6.1.4 Decentralized D-Channel Processing, Multiplexed plus Dedicated
HDLC-Control
Especially when packet data is supported in the D-channel one multiplexed HDLC
controller may create a bottleneck situation. One solution to overcome this problem is
the combination of the multiplexing scheme with additional layer-2 controllers which can
be temporarily assigned to individual subscribers on request.
In normal operation all subscribers are managed by the D-channel arbiter and share
SACCO-A. When a subscriber requests a special type of service, the system can switch
a dedicated HDLC controller and exclude this subscriber temporarily from the arbitration.
For small systems SACCO-B, for bigger systems IDECs may be used as an assignable
controller resource.
ITS05812
EPIC
R
ARBITER
SACCO CH-A
SACCO CH-B
ELIC
R
μ
P
R
IOM -2 Interface
R
IDEC
IDEC
R
s + p
Data
B
B
B
B
B
S
B
...
Example Frame Structure
p-Data
s-Data
s-Data
PCM
Highway
Packet Highway with
Collision Resolution