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发表于 2007-12-10 14:10:56
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt 18pt; TEXT-INDENT: -18pt; LINE-HEIGHT: 14.65pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-layout-grid-align: none; mso-list: l0 level1 lfo1; tab-stops: list 18.0pt" align=left><FONT face="Times New Roman"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt; mso-font-kerning: 0pt; mso-fareast-font-family: 'Times New Roman'"><SPAN style="mso-list: Ignore">
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1.<SPAN style="FONT: 7pt 'Times New Roman'"> </SPAN></SPAN></SPAN><SPAN lang=EN-US style="COLOR: black; mso-bidi-font-size: 10.5pt; mso-font-kerning: 0pt">Refer to the exhibit. How will router A choose a path to the <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:chsdate Year="1899" Month="12" Day="30" IsLunarDate="False" IsROCDate="False" w:st="on">10.1.2</st1:chsdate>.0/24 network when different routing protocols are configured? (Choose three.) </SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt 18pt; TEXT-INDENT: -18pt; LINE-HEIGHT: 14.65pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-layout-grid-align: none; mso-list: l0 level1 lfo1; tab-stops: list 18.0pt" align=left><FONT face="Times New Roman"><SPAN lang=EN-US style="COLOR: black; mso-bidi-font-size: 10.5pt; mso-font-kerning: 0pt"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></SPAN></FONT> </P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><v:shapetype id=_x0000_t75 coordsize="21600,21600" o:spt="75" o:preferrelative="t" path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"></v:path><o:lock v:ext="edit" aspectratio="t"></o:lock></v:shapetype><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 12.65pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-layout-grid-align: none" align=left><SPAN lang=EN-US style="COLOR: black; mso-bidi-font-size: 10.5pt; mso-font-kerning: 0pt"><FONT face="Times New Roman">A. If RIPv2 is the routing protocol, only the path AD will be installed in the routing table by default.<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 12.65pt; TEXT-ALIGN: left; mso-line-height-rule: exactly; mso-layout-grid-align: none" align=left><SPAN lang=EN-US style="COLOR: black; mso-bidi-font-size: 10.5pt; mso-font-kerning: 0pt"><FONT face="Times New Roman">B. If RIPv2 is the routing protocol, the equal cost paths ABD and ACD will be installed in the routing table by<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">C. If EIGRP is the routing protocol, only the path AD will be installed in the routing table by default. <o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">D. If EIGRP is the routing protocol, the equal cost paths ABD and ACD will be installed in the routing table by default. <o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">E. If EIGRP and OSPF are both running on the network, the EIGRP paths will be installed in the routing table. <o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">F. If EIGRP and OSPF are both running on the network, the OSPF paths will be installed in the routing table. <o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">Answer: ADE<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">解释一下:不同的路由协议都有自己的选路的原则,原则不同,选出的路径也不尽相同。</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">RIP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是根据跳数来选路的,跳数越少路径越优先,所以</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">Router A</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">选择路径</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">AD</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">到达</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">10.1.2.0/24</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的网段,因为这条路径的跳数最小。</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">EIGRP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是根据复合度量值来判断路径的优劣的。复合度量值的参数有:带宽,延时,负载,可靠性和最小传输单元。默认只根据带宽和延时来计算他的</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">metric</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。这样判断路径</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">ACD </FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">ABD</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">将有相同的度量值,所以他们将等价出现在路由表中。</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">OSPF</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的度量值没有明确的规定是什么,在</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">CISCO</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中,我们采用带宽来判断,公式为</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">metric=10<SUP>8</SUP>/bandwidth (kbps) ,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">通过这样计算可以算出路径</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">ACD ABD</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">有相同的</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">metric</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">值,也会等价负载均衡。</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">但是当有多个路由协议运行在相同的网络中,我们可以通过比较管理距离来判断到相同的目的地的多个路由协议选出的多个路径中的最优的路径,管理距离越小越优先。</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">RIP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的管理距离为</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">120</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">,</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman"> EIGRP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的管理距离为</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">90</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">,</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">OSPF</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的管理距离为</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">110</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">,所以如果</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">EIGRP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">OSPF</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">同时运行在上图中的网络中,</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><FONT face="Times New Roman">EIGRP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的路径将被放入到路由表中。</SPAN><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><o:p><FONT face="Times New Roman"> </FONT></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"><o:p><FONT face="Times New Roman"> </FONT><FONT face=宋体></SPAN><SPAN lang=EN-US style="COLOR: black; mso-bidi-font-size: 10.5pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN></P> |
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