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<h2>Gb interface planning</h2>

<p>The Gb interface is the interface between the BSS and the
serving GPRS support node (SGSN). When examining the Gb interface in more
depth, the following pieces of hardware can be found: </p>


<ul>
<li><p>Packet Control Unit (PCU) at the BSS side</p>
</li>
<li><p>Packet Processing Unit (PAPU) at the GPRS IP backbone side.</p>
</li>
</ul>


<p>Each PCU has its own separate Gb interface to the SGSN. The Gb interface
is implemented using the logical Frame Relay connection on top of E1 PCM links.</p>


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connection in between</p>
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<p>The Gb interface planning can be divided into the following
three areas: </p>


<ul>
<li><p>BSC dimensioning</p>
</li>
<li><p>Frame Relay connection planning</p>
</li>
<li><p>SGSN dimensioning</p>
</li>
</ul>


<p>For more information on SGSN planning, refer to the <em>Core network
planning guide</em>.</p>


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