pt7a6527 Pericom Technology Inc, pt7a6527 Datasheet - Page 5

• Manufacturer Part Number: pt7a6527
• Description: Hdlc Controller
• Manufacturer: Pericom Technology Inc

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Line Cards in De-Centralized or Mixed Signaling / Data
Packet Handling Architectures
The PT7A6527 can be used on peripheral line cards to process
D-channel packets for ISDN subscribers. The PCM Controller
has the layer-1 controlling capacity and a B-channel switching
capacity for a total of 32 subscribers. The B and D channels
and the control information for eight subscribers are carried by
one IOM interface. Thus a line card dimensioned for 32-ISDN
subscribers may employ up to eight devices, two for each
IOM
Communication Controller (6525) with two HDLC channels,
or another PT7A6527 may be used to transmit and receive
signaling via the system highway in a common channel. Again,
such a common channel may be shared among several line
cards, due to the statistical multiplexing capability of these
controllers.
In
architectures, the processing capacity of a line card is usually
dimensioned so as to avoid blocking situations even under
maximum conceivable D-channel traffic conditions. It may
Figure 2 Line Card in a De-Centralized D-channel Handing Architecture
PT0080(02/09)
completely
connection
Line Transceivers
X8
S/U
S/U
c.c.s/p=Common channel for signaling and for packed data, respectively
C/I,MON=Command/Indication and MONITOR channels forthe interface
Note:
de-centralized
(figure
PT7A6527
D
2).
A
D-channel
High
D
PT7A6527
Level
µP
processing
C/I, MONITOR
Serial
5
D
D
sometimes be more advantageous to perform p-packet
handling in a centralized manner while keeping s-packet
handling on the line cards. A statistical increase in p-packet
traffic has then no effect on the line card, and can be easily
dealt with by one of the modular architectures for a central
packet handler shown in the previous section. A more
effective sharing of the total p-packet handling capacity is the
result, especially in a situation where p-packet traffic patterns
vary widely from one subscriber group to another.
The use of a PT7A6527 in the mixed D-channel processing
architecture is illustrated in figure 3.
The additional transparent data connections supported by the
PT7A6527 enable a merging of p and s packets into one D
channel. Possible collision situations are dealt with by the
PT7A6527 which uses either the additional collision detect
line (figure 3) or a time slot on the system highway (figure 3)
from the line card to the central packet handler.
PT7A6555
PT7A6527/
PT7A652
s, p
B
s, p
c.c.s + c.c.p
HDLC controller
System
Highways
Data Sheet
PT7A6527
Ver:4