tr><td class="paramname">proto</td><td>the PROTOCOL to be set in the IP header </td></tr>
    <tr><td class="paramname">netif</td><td>the netif on which to send this packet </td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>ERR_OK if the packet was sent OK ERR_BUF if p doesn't have enough space for IP/LINK headers returns errors returned by netif-&gt;output</dd></dl>
<dl class="section note"><dt>Note</dt><dd>ip_id: RFC791 "some host may be able to simply use
 unique identifie