vlan13.htm

V-LAN 虚拟局域网的学习笔记

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     <p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
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     lang=EN-US style='font-family:宋体'>④</span></b><span lang=EN-US><o:p></o:p></span></p>
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     style='mso-bidi-font-weight:normal'><span style='font-family:宋体;
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     lang=EN-US>A</span></b><b style='mso-bidi-font-weight:normal'><span
     style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
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     style='mso-bidi-font-weight:normal'><span style='font-family:宋体;
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<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='mso-bidi-font-size:10.5pt;font-family:宋体'>首先计算机</span><span lang=EN-US
style='mso-bidi-font-size:10.5pt'>A</span><span style='mso-bidi-font-size:10.5pt;
font-family:宋体'>向交换机<span lang=EN-US>1送出数据（①），其后数据被转发给路由器（②）进行</span></span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>VLAN</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体'>间路由。路由后的数据，再从汇聚链路返回交换机<span lang=EN-US>1（③）。由于通信目标计算机</span></span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>C</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体'>并不直连在交换机<span lang=EN-US>1上，因此还需要经过汇聚链路转发到交换机2（④）。在交换机2上，数据最终被转发到</span></span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>C</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体'>所连的端口<span lang=EN-US>2上，这才完成整个流程（⑤）。<o:p></o:p></span></span></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='mso-bidi-font-size:10.5pt;font-family:宋体'>在这个例子中，仅由<span lang=EN-US>2台交换机构成网络，其数据流已经如此复杂，<span
style='color:red'>如果构建横跨多台交换机的</span></span></span><span lang=EN-US
style='mso-bidi-font-size:10.5pt;color:red'>VLAN</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;color:red'>的话，每个数据流的流向显然会更加难以把握</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体'>。<span lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
lang=EN-US style='font-size:13.5pt'><br>
</span><b style='mso-bidi-font-weight:normal'><span style='font-size:12.0pt;
font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman";color:red'>网络的逻辑结构与物理结构</span></b><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='font-size:12.0pt;color:red'><o:p></o:p></span></b></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>为了对应日渐复杂化的数据流，管理员需要从“<span style='color:blue'>逻辑结构</span>”与“<span
style='color:blue'>物理结构</span>”两方面入手，把握好网络的现状。</span></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>物理结构，指的是从物理层和数据链路层观察到的网络的现状，表示了网络的物理布线形态和</span><span
lang=EN-US>VLAN</span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>的设定等等。</span></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>而逻辑结构，则表示从网络层以上的层面观察到的网络结构。下面我们就试着以路由器为中心分析一个</span><span
lang=EN-US>IP</span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>网络的逻辑结构。</span></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>还是先前的那个例子，描绘了布线形态和</span><span lang=EN-US>VLAN</span><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>设定的“物理结构”如下图所示。</span></p>

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      <p class=MsoNormal><span style='font-family:宋体;mso-ascii-font-family:
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