热点科技
标题:
路由器常识
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作者:
yueli009
时间:
2006-2-28 23:26
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器分类</SPAN><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman" size=3> </FONT></SPAN></SPAN><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman" size=3> </FONT></SPAN></SPAN></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器产品，按照不同的划分标准有多种类型。常见的分类有以下几类：</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><SPAN lang=EN-US><?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p><FONT face="Times New Roman" size=3> </FONT></o:p></SPAN></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">按性能档次分为高、中、低档路由器。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">通常将路由器吞吐量大于</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">40Gbps</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的路由器称为高档路由器，背吞吐量在</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">25Gbps~40Gbps</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">之间的路由器称为中档路由器，而将低于</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">25Gbps</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的看作低档路由器。当然这只是一种宏观上的划分标准，各厂家划分并不完全一致，实际上路由器档次的划分不仅是以吞吐量为依据的，是有一个综合指标的。以市场占有率最大的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Cisco</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">公司为例，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">12000</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">系列为高端路由器，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">7500</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">以下系列路由器为中低端路由器。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><SPAN lang=EN-US><o:p><FONT face="Times New Roman" size=3> </FONT></o:p></SPAN></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">从结构上分为“模块化路由器”和“非模块化路由器”。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模块化结构可以灵活地配置路由器，以适应企业不断增加的业务需求，非模块化的就只能提供固定的端口。通常中高端路由器为模块化结构，低端路由器为非模块化结构。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><SPAN lang=EN-US><o:p><FONT face="Times New Roman" size=3> </FONT></o:p></SPAN></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">从功能上划分，可将路由器分为“骨干级路由器”，“企业级路由器”和“接入级路由器”。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">骨干级路由器是实现企业级网络互连的关键设备，它数据吞吐量较大，非常重要。对骨干级路由器的基本性能要求是高速度和高可靠性。为了获得高可靠性，网络系统普遍采用诸如热备份、双电源、双数据通路等传统冗余技术，从而使得骨干路由器的可靠性一般不成问题。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">企业级路由器连接许多终端系统，连接对象较多，但系统相对简单，且数据流量较小，对这类路由器的要求是以尽量便宜的方法实现尽可能多的端点互连，同时还要求能够支持不同的服务质量。</SPAN><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">接入级路由器主要应用于连接家庭或</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ISP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">内的小型企业客户群体。</SPAN><SPAN lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><SPAN lang=EN-US><o:p><FONT face="Times New Roman" size=3> </FONT></o:p></SPAN></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">按所处网络位置划分通常把路由器划分为“边界路由器”和“中间节点路由器”。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">很明显</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">"</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">边界路由器</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">"</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是处于网络边缘，用于不同网络路由器的连接；而</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">"</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中间节点路由器</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">"</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">则处于网络的中间，通常用于连接不同网络，起到一个数据转发的桥梁作用。由于各自所处的网络位置有所不同，其主要性能也就有相应的侧重，如中间节点路由器因为要面对各种各样的网络。如何识别这些网络中的各节点呢？靠的就是这些中间节点路由器的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">MAC</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">地址记忆功能。基于上述原因，选择中间节点路由器时就需要在</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">MAC</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">地址记忆功能更加注重，也就是要求选择缓存更大，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">MAC</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">地址记忆能力较强的路由器。但是边界路由器由于它可能要同时接受来自许多不同网络路由器发来的数据，所以这就要求这种边界路由器的背板带宽要足够宽，当然这也要与边界路由器所处的网络环境而定。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><SPAN lang=EN-US><o:p><FONT face="Times New Roman" size=3> </FONT></o:p></SPAN></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">从性能上可分为“线速路由器”以及“非线速路由器”。</SPAN></FONT></P>
<P =Msonormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left><FONT size=3><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所谓</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">"</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">线速路由器</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">"</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">就是完全可以按传输介质带宽进行通畅传输，基本上没有间断和延时。通常线速路由器是高端路由器，具有非常高的端口带宽和数据转发能力，能以媒体速率转发数据包；中低端路由器是非线速路由器。但是一些新的宽带接入路由器也有线速转发能力。</SPAN></FONT></P>
作者:
yueli009
时间:
2006-2-28 23:27
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器处理器</SPAN><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman" size=2> </FONT></SPAN></SPAN></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">与计算机一样，路由器也包含了一个中央处理器</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">也就是所说的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">CPU</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。不同系列和型号的路由器，其中的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">CPU</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">也不尽相同。</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Cisco</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器一般采用</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Motorola 68030</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Orion/R4600</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">两种处理器。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><O:P><FONT face="Times New Roman" size=2> </FONT></O:P></SPAN></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">无论在中低端路由器还是在高端路由器中，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">CPU</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">都是路由器的心脏。通常在中低端路由器当中，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">CPU</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">负责交换路由信息、路由表查找以及转发数据包。在路由器中，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">CPU</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的能力直接影响路由器的吞吐量（路由表查找时间）和路由计算能力（影响网络路由收敛时间）。在高端路由器中，通常包转发和查表由</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ASIC</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">芯片完成，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">CPU</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">只实现路由协议、计算路由以及分发路由表。由于技术的发展，路由器中许多工作都可以由硬件实现（专用芯片）。</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">CPU</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">性能并不完全反映路由器性能。路由器性能由路由器吞吐量、时延和路由计算能力等指标体现。</SPAN><SPAN lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman">FLASH</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">内存</SPAN><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>Flash</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">内存，也叫闪存，是路由器当中常用的一种内存类型。它是可读写的存储器，在系统重新启动或关机之后仍能保存数据。</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Flash</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中存放着当前使用中的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（路由器操作系统）。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT size=2></FONT></SPAN></SPAN> </P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器内存</SPAN><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN><SPAN style="mso-spacerun: yes"> </SPAN></FONT></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器中可能有多种内存，例如</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Flash</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（闪存）、</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">DRAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（动态内存）等。内存用作存储配置、路由器操作系统、路由协议软件等内容。在中低端路由器中，路由表可能存储在内存中。通常来说路由器内存越大越好（不考虑价格）。但是与</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">CPU</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">能力类似，内存同样不直接反映路由器性能与能力。因为高效的算法与优秀的软件可能大大节约内存。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><O:P><FONT face="Times New Roman" size=2></FONT></O:P></SPAN></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器采用了以下几种不同类型的内存，每种内存以不同方式协助路由器工作。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>*</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">只读内存</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">(ROM) </FONT></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>*</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">闪存</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">(FLASH) </FONT></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>*</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">随机存取内存</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">(RAM) </FONT></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US> </SPAN><SPAN lang=EN-US><FONT face="Times New Roman">*</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">非易失性</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">RAM(NVRAM)</FONT></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><O:P><FONT face="Times New Roman" size=2></FONT></O:P></SPAN></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>1.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">只读内存（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ROM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">只读内存（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ROM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）在</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Cisco</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器中的功能与计算机中的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ROM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">相似，主要用于系统初始化等功能。</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ROM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中主要包含：</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">1</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）系统加电自检代码（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">POST</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">），用于检测路由器中各硬件部分是否完好；</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">2</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）系统引导区代码（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">BootStrap</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">），用于启动路由器并载入</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">操作系统；</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">3</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）备份的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">操作系统，以便在原有</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">操作系统被删除或破坏时使用。通常，这个</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">比现运行</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的版本低一些，但却足以使路由器启动和工作。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">顾名思义，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ROM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是只读存储器，不能修改其中存放的代码。如要进行升级，则要替换</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ROM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">芯片。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><O:P><FONT face="Times New Roman" size=2></FONT></O:P></SPAN></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>2.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">闪存（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Flash</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">闪存（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Flash</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）是可读可写的存储器，在系统重新启动或关机之后仍能保存数据。</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Flash</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中存放着当前使用中的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。事实上，如果</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Flash</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">容量足够大，甚至可以存放多个操作系统，这在进行</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">升级时十分有用。当不知道新版</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是否稳定时，可在升级后仍保留旧版</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，当出现问题时可迅速退回到旧版操作系统，从而避免长时间的网路故障。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><O:P><FONT face="Times New Roman" size=2></FONT></O:P></SPAN></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>3.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">非易失性</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">RAM(NVRAM)</FONT></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">非易失性</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">RAM(Nonvolatile RAM)</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是可读可写的存储器，在系统重新启动或关机之后仍能保存数据。由于</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">NVRAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">仅用于保存启动配置文件（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Startup-Config</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">），故其容量较小，通常在路由器上只配置</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">32KB~128KB</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">大小的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">NVRAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。同时，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">NVRAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的速度较快，成本也比较高。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><O:P><FONT face="Times New Roman" size=2></FONT></O:P></SPAN></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>4.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">随机存储器</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">(RAM)</FONT></SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>RAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">也是可读可写的存储器，但它存储的内容在系统重启或关机后将被清除。和计算机中的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">RAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">一样，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Cisco</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">路由器中的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">RAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">也是运行期间暂时存放操作系统和数据的存储器，让路由器能迅速访问这些信息。</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">RAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的存取速度优于前面所提到的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">3</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">种内存的存取速度。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><FONT size=2><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">运行期间，</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">RAM</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中包含路由表项目、</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ARP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">缓冲项目、日志项目和队列中排队等待发送的分组。除此之外，还包括运行配置文件（</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">Running-config</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）、正在执行的代码、</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">IOS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">操作系统程序和一些临时数据信息。</SPAN></FONT></P>
<P style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: left" align=left ="Msonormal"><SPAN lang=EN-US><O:P><FONT face="Times New Roman" size=2></FONT></O:P></SPAN></P><FONT size=2><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN></FONT><FONT size=2><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">路由器的类型不同，</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">IOS</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">代码的读取方式也不同。如</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">Cisco 2500</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">系列路由器只在需要时才从</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">Flash</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">中读入部分</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">IOS</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">；而</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">Cisco 4000</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">系列路由器整个</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">IOS</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">必须先全部装入</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">RAM</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">才能运行。因此，前者称为</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">Flash</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">运行设备（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">Run from Flash</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">），后者称为</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">RAM</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">运行设备（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">Run from RAM</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA">）。</SPAN></FONT><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA"> </SPAN><edited><editID>yueli009</editID><editDate>2006-2-28 15:35:56</editDate></edited>
作者:
yueli009
时间:
2006-2-28 23:30
<P><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">路由器</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN><?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">要解释路由器的概念，首先得知道什么是路由。所谓“路由”，是指把数据从一个地方传送到另一个地方的行为和动作，而路由器，正是执行这种行为动作的机器，它的英文名称为</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">Router,</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">是一种连接多个网络或网段的网络设备，它能将不同网络或网段之间的数据信息进行“翻译”，以使它们能够相互“读懂”对方的数据，从而构成一个更大的网络。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">简单的讲，路由器主要有以下几种功能：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">第一，网络互连，路由器支持各种局域网和广域网接口，主要用于互连局域网和广域网，实现不同网络互相通信；</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">第二，数据处理，提供包括分组过滤、分组转发、优先级、复用、加密、压缩和防火墙等功能；</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">第三，网络管理，路由器提供包括配置管理、性能管理、容错管理和流量控制等功能。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">为了完成“路由”的工作，在路由器中保存着各种传输路径的相关数据－－路由表（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">Routing Table</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">），供路由选择时使用。路由表中保存着子网的标志信息、网上路由器的个数和下一个路由器的名字等内容。路由表可以是由系统管理员固定设置好的，也可以由系统动态修改，可以由路由器自动调整，也可以由主机控制。在路由器中涉及到两个有关地址的名字概念，那就是：静态路由表和动态路由表。由系统管理员事先设置好固定的路由表称之为静态（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">static</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">）路由表，一般是在系统安装时就根据网络的配置情况预先设定的，它不会随未来网络结构的改变而改变。动态（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">Dynamic</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">）路由表是路由器根据网络系统的运行情况而自动调整的路由表。路由器根据路由选择协议（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">Routing Protocol</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">）提供的功能，自动学习和记忆网络运行情况，在需要时自动计算数据传输的最佳路径。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">为了简单地说明路由器的工作原理，现在我们假设有这样一个简单的网络。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">A</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">、</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">B</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">、</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">、</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">D</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">四个网络通过路由器连接在一起。</SPAN></P>
<P><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312"></SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: red; FONT-FAMILY: ˎ̥_GB2312"><?:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><V:SHAPE id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><V:STROKE joinstyle="miter"></V:STROKE><V:ULAS><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:ULAS><V:PATH gradientshapeok="t" o:extrusionok="f" o:connect="rect"></V:PATH><O:LOCK aspectratio="t" v:ext="edit"></O:LOCK></V:SHAPE><V:SHAPE id=_x0000_i1025 style="WIDTH: 255pt; HEIGHT: 135pt" ="#_x0000_t75" alt=""><V:IMAGEDATA target="_blank" o:href="http://publish.it168.com/cWord/images/137285.jpg" src="file:///C:\DOCUME~1\yueli009\LOCALS~1\Temp\msohtml1\01\clip_image001.jpg" target="_blank"></V:IMAGE></V:SHAPE></SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: red; FONT-FAMILY: ˎ̥_GB2312; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-bidi-font-family: 'Times New Roman'; mso-ansi-: EN-US; mso-fareast-: ZH-CN; mso-bidi-: AR-SA"><?:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><V:SHAPE id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><FONT face="宋体, MS Song"><V:STROKE joinstyle="miter"></V:STROKE></FONT><V:ULAS><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:ULAS><V:PATH gradientshapeok="t" o:extrusionok="f" o:connect="rect"></V:PATH><?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><O:LOCK aspectratio="t" v:ext="edit"></O:LOCK></V:SHAPE><V:SHAPE id=_x0000_i1025 style="WIDTH: 108pt; HEIGHT: 57pt" ="#_x0000_t75" alt=""><V:IMAGEDATA target="_blank" o:href="http://publish.it168.com/cWord/images/137285.jpg" src="file:///C:\DOCUME~1\yueli009\LOCALS~1\Temp\msohtml1\01\clip_image001.jpg" target="_blank"></V:IMAGE></V:SHAPE></SPAN><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">现在我们来看一下网络环境下路由器又是如何发挥其路由、数据转发作用的。现假设网络</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">A</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">中一个用户</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">A1</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">要向</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">网络中的</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">用户发送一个请求信号时，信号传递的步骤如下：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">第</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">1</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">步：用户</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">A1</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">将目的用户</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">的地址</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">，连同数据信息以数据帧的形式通过集线器或交换机以广播的形式发送给同一网络中的所有节点，当路由器</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">A5</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">端口侦听到这个地址后，分析得知所发目的节点不是本网段的，需要路由转发，就把数据帧接收下来。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">第</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">2</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">步：路由器</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">A5</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">端口接收到用户</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">A1</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">的数据帧后，先从报头中取出目的用户</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">的</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">IP</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">地址，并根据路由表计算出发往用户</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">的最佳路径。因为从分析得知到</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">的网络</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">ID</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">号与路由器的</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C5</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">网络</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">ID</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">号相同，所以由路由器的</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">A5</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">端口直接发向路由器的</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C5</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">端口应是信号传递的最佳途经。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">第</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">步：路由器的</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C5</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">端口再次取出目的用户</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">的</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">IP</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">地址，找出</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">的</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">IP</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">地址中的主机</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">ID</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">号，如果在网络中有交换机则可先发给交换机，由交换机根据</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">MAC</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">地址表找出具体的网络节点位置；如果没有交换机设备则根据其</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">IP</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">地址中的主机</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">ID</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">直接把数据帧发送给用户</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">C3</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">，这样一个完整的数据通信转发过程也完成了。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">从上面可以看出，不管网络有多么复杂，路由器其实所作的工作就是这么几步，所以整个路由器的工作原理基本都差不多。当然在实际的网络中还远比上图所示的要复杂许多，实际的步骤也不会像上述那么简单，但总的过程是这样的。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><O:P></O:P></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">目前，生产路由器的厂商，国外主要有</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">CISCO</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">（思科）公司、北电网络等，国内厂商包括华为等。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"> <O:P></O:P></SPAN></P><edited><editID>yueli009</editID><editDate>2006-2-28 15:51:23</editDate></edited>
作者:
yueli009
时间:
2006-2-28 23:30
<P><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">路由表</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN><SPAN style="mso-spacerun: yes"> </SPAN><?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">路由器的主要工作就是为经过路由器的每个数据帧寻找一条最佳传输路径，并将该数据有效地传送到目的站点。由此可见，选择最佳路径的策略即路由算法是路由器的关键所在。为了完成这项工作，在路由器中保存着各种传输路径的相关数据——路由表（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">Routing Table</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">），供路由选择时使用。打个比方，路由表就像我们平时使用的地图一样，标识着各种路线，路由表中保存着子网的标志信息、网上路由器的个数和下一个路由器的名字等内容。路由表可以是由系统管理员固定设置好的，也可以由系统动态修改，可以由路由器自动调整，也可以由主机控制。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><o:p></o:p></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">1</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">．静态路由表</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"> <o:p></o:p></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">由系统管理员事先设置好固定的路由表称之为静态（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">static</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">）路由表，一般是在系统安装时就根据网络的配置情况预先设定的，它不会随未来网络结构的改变而改变。</SPAN></P>
<P><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312"></SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">2</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">．动态路由表</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"> <SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
<P style="TEXT-INDENT: 21.75pt"><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">动态（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">Dynamic</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">）路由表是路由器根据网络系统的运行情况而自动调整的路由表。路由器根据路由选择协议（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">Routing Protocol</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">）提供的功能，自动学习和记忆网络运行情况，在需要时自动计算数据传输的最佳路径。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><o:p></o:p></SPAN></P>
<P><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">路由器通常依靠所建立及维护的路由表来决定如何转发。路由表能力是指路由表内所容纳路由表项数量的极限。由于</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">Internet</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">上执行</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312">BGP</SPAN><SPAN style="FONT-SIZE: 10.5pt; COLOR: windowtext; mso-ascii-font-family: ˎ̥_GB2312; mso-hansi-font-family: ˎ̥_GB2312">协议的路由器通常拥有数十万条路由表项，所以该项目也是路由器能力的重要体现。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; COLOR: windowtext; FONT-FAMILY: ˎ̥_GB2312"><o:p></o:p></SPAN></P>
作者:
tao123
时间:
2006-3-1 23:48
路过<IMG src="smileys/smiley1.gif" border="0">，虽然是基础，但也是好东西，要好好学习!!!
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