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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:宋體'>首先計算機</span><span lang=EN-US
style='mso-bidi-font-size:10.5pt'>A</span><span style='mso-bidi-font-size:10.5pt;
font-family:宋體'>向交換機<span lang=EN-US>1送出數(shù)據(jù)（①），其后數(shù)據(jù)被轉(zhuǎn)發(fā)給路由器（②）進行</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:宋體'>間路由。路由后的數(shù)據(jù)，再從匯聚鏈路返回交換機<span lang=EN-US>1（③）。由于通信目標計算機</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:宋體'>并不直連在交換機<span lang=EN-US>1上，因此還需要經(jīng)過匯聚鏈路轉(zhuǎn)發(fā)到交換機2（④）。在交換機2上，數(shù)據(jù)最終被轉(zhuǎn)發(fā)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:宋體'>所連的端口<span lang=EN-US>2上，這才完成整個流程（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:宋體'>在這個例子中，僅由<span lang=EN-US>2臺交換機構(gòu)成網(wǎng)絡(luò)，其數(shù)據(jù)流已經(jīng)如此復雜，<span
style='color:red'>如果構(gòu)建橫跨多臺交換機的</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:宋體;color:red'>的話，每個數(shù)據(jù)流的流向顯然會更加難以把握</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋體'>。<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
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</span><b style='mso-bidi-font-weight:normal'><span style='font-size:12.0pt;
font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman";color:red'>網(wǎng)絡(luò)的邏輯結(jié)構(gòu)與物理結(jié)構(gòu)</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:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>為了對應(yīng)日漸復雜化的數(shù)據(jù)流，管理員需要從“<span style='color:blue'>邏輯結(jié)構(gòu)</span>”與“<span
style='color:blue'>物理結(jié)構(gòu)</span>”兩方面入手，把握好網(wǎng)絡(luò)的現(xiàn)狀。</span></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>物理結(jié)構(gòu)，指的是從物理層和數(shù)據(jù)鏈路層觀察到的網(wǎng)絡(luò)的現(xiàn)狀，表示了網(wǎng)絡(luò)的物理布線形態(tài)和</span><span
lang=EN-US>VLAN</span><span style='font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>的設(shè)定等等。</span></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>而邏輯結(jié)構(gòu)，則表示從網(wǎng)絡(luò)層以上的層面觀察到的網(wǎng)絡(luò)結(jié)構(gòu)。下面我們就試著以路由器為中心分析一個</span><span
lang=EN-US>IP</span><span style='font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>網(wǎng)絡(luò)的邏輯結(jié)構(gòu)。</span></p>

<p class=MsoNormal align=left style='text-align:left;mso-pagination:widow-orphan'><span
style='font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>還是先前的那個例子，描繪了布線形態(tài)和</span><span lang=EN-US>VLAN</span><span
style='font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>設(shè)定的“物理結(jié)構(gòu)”如下圖所示。</span></p>

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