Unstructured Ds1 - 3Com SuperStack II PathBuilder S330 Reference Manual

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PPENDIX ATH UILDER
S330/S310 M A
ODULE AND PPLICATION
Structured data DS0s allow for clear channel signaling (CCS). As opposed to CAS,
in which signaling is done on all channels, in clear channel signaling (CCS) one
channel is used to signal for the other channels.
The PathBuilder S330/S310 software can also monitor a full 8-bit pattern on a DS0
to determine circuit activity. This is the basis for the two supported types of
dynamic bandwidth allocation (DBA):
Structured voice DBA
Structured data DBA
Structured Voice DBA When a CBR port is configured as structured voice,
signaling bits of voice channels are carried along with their payload in AAL1 cells.
These signaling bits, which are received from T1/E1 framers, are stored in buffers
provided in the SAR processor. The CBR software periodically reads the stored
signaling bits and checks for an idle condition of voice channels with on-hook
detection enabled.
When an on-hook (idle) signal is detected, the CBR virtual circuit is deactivated,
and the bandwidth reserved for that channel is released for other uses (such as
VBR traffic).
When an off-hook signal is detected, the CBR virtual circuit is activated.
Use structured voice circuits with DBA for CAS (channel associated signaling)
applications.
Structured Data DBA When a CBR port is configured as structured data, only
DS0 payload bytes are carried in AAL1 cells. These data cells are stored in buffers
provided in the SAR processor. The CBR software periodically reads the stored data
bits and checks for an idle code in the stored data bits of each DS0 channel. All
virtual circuits in the port use a user-selected DBA bit mask to mask off bits that
are not a portion of the idle code.
When an on-hook condition (idle code) is detected, the CBR virtual circuit is
deactivated, and the bandwidth reserved for that channel is released for other
uses.
When an off-hook condition (no idle code) is detected, the CBR virtual circuit is
activated.
Use structured data circuits with DBA for CCS (common channel signaling)
applications.
A structured DS1 channel will not pass the original DS1 frame to the remote end.
For instance, ESF network management will terminate at the PathBuilder
S330/S310 on a structured DS1, so CSU-to-CSU Facility Data Link (FDL)
communication will not be possible. FDL communication is possible with

unstructured DS1.

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