f02d9da80fd66b4f986d2c53d7231ddb">err_t</a> tcp_zero_window_probe </td>
          <td>(</td>
          <td class="paramtype">struct <a class="el" href="structtcp__pcb.html">tcp_pcb</a> *&#160;</td>
          <td class="paramname"><em>pcb</em></td><td>)</td>
          <td></td>
        </tr>
      </table>
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<p>Send persist timer zero-window probes to keep a connection active when a window update is lost.</p>
<p>Called by <a class="el" href="tcp_8c.html#a421fb42ef919018e14ae413adfee9