📄 001_18.htm
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<DIV class=im1><IMG height=553 src="1_18.files/001_2_18_2.jpg" width=463
border=0></DIV><!-- text starts here --><SPAN class=ps0><NOBR>合<SPAN
class=em1>SDP<SPAN class=em0>（</SPAN>Session Description Protocol<SPAN
class=em0>，</SPAN></SPAN>会话描述协议）的规定（<SPAN class=em1>RFC
2327</SPAN>）。</NOBR></SPAN> <SPAN class=ps1><NOBR><SPAN class=ft1>SDP<SPAN
class=em0>协议将在下一节中讨论。</SPAN>S/MGCP<SPAN class=em0>命令中可能包含的典型</SPAN>SDP<SPAN
class=em0>语法是：</SPAN></SPAN></NOBR></SPAN> <SPAN class=ps2><NOBR><SPAN
class=ft1>v=0</SPAN></NOBR></SPAN> <SPAN class=ps3><NOBR><SPAN class=ft1>c=IN IP
128.96.41.1</SPAN></NOBR></SPAN> <SPAN class=ps4><NOBR><SPAN class=ft1>m=audio
3456 RTP/AVP 0</SPAN></NOBR></SPAN> <SPAN class=ps5><NOBR>这个会话描述符标识了<SPAN
class=em1>SDP</SPAN>协议版本为<SPAN class=em1>0</SPAN>、<SPAN
class=em1>Ipv4</SPAN>网络、<SPAN class=em1>IP</SPAN>端点地址为<SPAN
class=em1>128.96.41.1</SPAN>、连接方</NOBR></SPAN> <SPAN
class=ps6><NOBR>式设置为音频方式、<SPAN class=em1>RTP</SPAN>端口设置为<SPAN
class=em1>3456</SPAN>、使用<SPAN class=em1>0</SPAN>类有效载荷的用户配置（<SPAN
class=em1>G.7111</SPAN>非压缩<SPAN class=em1>64K</SPAN></NOBR></SPAN> <SPAN
class=ps7><NOBR>语音）。载荷类型将在后面的<SPAN class=em1>RTP</SPAN>部分讨论。为了分析<SPAN
class=em1>S/MGCP</SPAN>中的<SPAN class=em1>SDP</SPAN>参数的语法，在呼叫</NOBR></SPAN> <SPAN
class=ps8><NOBR>流分析过程中将看到实时捕获的真实包。</NOBR></SPAN> <SPAN class=ps9><NOBR><SPAN
class=ft1>12. <SPAN class=em3>包格式</SPAN></SPAN></NOBR></SPAN> <SPAN
class=ps10><NOBR>如前所述，<SPAN class=em1>S/MGCP</SPAN>是基于<SPAN
class=em1>ASCII</SPAN>文本的协议。这使得包的内容易于显示和理解，而不</NOBR></SPAN> <SPAN
class=ps11><NOBR><SPAN class=ft2>18 <SPAN class=em2>IP </SPAN><SPAN
class=em4>电话技术：稳定的</SPAN><SPAN class=em2>VoIP</SPAN><SPAN
class=em4>服务集成</SPAN></SPAN></NOBR></SPAN> <SPAN class=ps12><NOBR><SPAN
class=ft3>文档</SPAN></NOBR></SPAN> <SPAN class=ps13><NOBR><SPAN class=ft4>图<SPAN
class=em5>1-7 S/MGCP RQNT </SPAN>包格式（得到<SPAN
class=em5>HP-IA</SPAN>的许可）</SPAN></NOBR></SPAN> </BODY></HTML>
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