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<div class="div">
<h1>High Capacity Signalling Links on A interface</h1>

<p>The GSM network has been originally specified (GSM 08.08)
and designed to use 64 kbit/s CCS7 links in the A interface. Due to various
reasons, the CCS7 links can be congested in the A interface. The situation
could be improved with higher capacity CCS7 links on the A interface.</p>


<p>Higher capacity CCS7 links (128, 256 kbit/s) between the
BSC and MSC are now supported. They require the use of the Nokia BSC2i with
plug-in-unit AS7-V or the Nokia BSC3i with plug-in-unit AS7-B and the Nokia
MSCi with plug-in-unit AS7-A.</p>


<p>Normally, there are 4 timeslots reserved for 64kbit/s CCS7
links. However, with high capacity CCS7 link feature, there are always 16
timeslots reserved for the CCS7 usage regardless how many timeslots are actually
needed so having high capacity CCS7 links on A interface may have impact on
the maximum LapD capacity of BSC depending on the configuration.</p>


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<p>Table: Number of LapD links and CCS7 links per BCSU with or without High
capacity CCS7 link for high capacity BSC</p>


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<thead>
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<th colspan="1" rowspan="1" valign="top"><p></p>


 </th>
<th colspan="1" rowspan="1" valign="top"><p>64kbit/s CCS7 link</p>
</th>
<th colspan="1" rowspan="1" valign="top"><p>128 kbit/s CCS7 link</p>
</th>
<th colspan="1" rowspan="1" valign="top"><p>256 kbit/s CCS7 link</p>
</th>
</tr>
</thead>
<tbody>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>Maximum Number of CCS7 links</p>
</td>
<td colspan="1" rowspan="1"><p>4</p>
</td>
<td colspan="1" rowspan="1"><p>4</p>
</td>
<td colspan="1" rowspan="1"><p>4</p>
</td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>Maximum Number of BCFSIG LapD links</p>
</td>
<td colspan="1" rowspan="1"><p>32</p>
</td>
<td colspan="1" rowspan="1"><p>32</p>
</td>
<td colspan="1" rowspan="1"><p>32</p>
</td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>Maximum Number of TRXSIG LapD links </p>
</td>
<td colspan="1" rowspan="1"><p>64</p>
</td>
<td colspan="1" rowspan="1"><p>64</p>
</td>
<td colspan="1" rowspan="1"><p>64</p>
</td>
</tr>
<tr align="left" char="" charoff="50" valign="top">
<td colspan="1" rowspan="1"><p>Maximum number of LapD links (BCFSIG+TRXSIG+ISDN+ET-LapD)</p>
</td>
<td colspan="1" rowspan="1"><p>124</p>
</td>
<td colspan="1" rowspan="1"><p>112</p>


<p></p>
</td>
<td colspan="1" rowspan="1"><p>112</p>
</td>
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