笑傲江湖之三层交换篇

lily6189

<p class="MsoNormal" align="center" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center;"><span style="FONT-SIZE: 15.5pt; FONT-FAMILY: 黑体; mso-bidi-font-size: 10.0pt;"><font color="#3333cc">笑傲江湖之三层交换篇</font></span></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman"><font color="#3333cc">&nbsp;<p></p></font></font></span></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">令狐冲十四岁那年进入华山，那年岳琳珊八岁，岳不群白天给两人指点剑法，晚上令狐冲给小师妹讲故事哄她入睡。后来，岳不群陆续收了劳德诺、陆大有等徒弟，又忙于修炼紫霞神功，就没有时间指点徒弟。于是他做了一个</span><span lang="EN-US"><font face="Times New Roman">HUB</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，从此华山派实现教育电子化，岳不群在网上同时给每个徒弟授课，这种方法很快在五岳剑派内部推广。为了在五岳剑派之间互连，嵩山派掌门左冷禅研制出路由器，使得五岳剑派之间可以互联互通。令狐冲晚上就通过网络给小师妹讲故事。</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">很快，岳琳珊已经十六岁，变成了一个亭亭玉立的小姑娘了。令狐冲发现自己的目光总是不由自主的在小师妹身上停留，每次和小师妹在一起的时候，总能听到自己强烈的心跳声，经过了一段时间的茶饭不思后，终于有一天晚上，令狐冲在网上给小师妹发了一首情意绵绵的诗：你是风儿我是沙，你是蜜蜂我是花，你是梳子我是头发，你是牙膏我是牙刷。</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">第二天，华山派开例会，令狐冲怀着忐忑不安的心情来到了会议室，发现小师妹红着脸躲在师父后面，而其它的师弟都在偷偷朝自己笑，开完会，一个调皮的师弟就过来叫牙刷师兄，赶紧蒙面逃走。问陆大有，才知道是劳德诺用一个叫</span><span lang="EN-US"><font face="Times New Roman">NetXRay</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">的工具把自己在网上的大作全抓了出来。令狐冲懊悔万分，于是，闭门研究</span><span lang="EN-US"><font face="Times New Roman">RFC</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，成功的研制出</span><span lang="EN-US"><font face="Times New Roman">LanSwitch</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">。它能够识别设备</span><span lang="EN-US"><font face="Times New Roman">MAC</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址，这样，令狐冲发送给小师妹的数据只有她一个人能够收到。令狐冲晚上可以在网上放心的给小师妹讲故事，偶尔手痒还能敲几句平时心里想又说不出口的话来过瘾，然后，红着脸想象小师妹看到后的表情。</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman"><span style="mso-spacerun: yes;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span><span style="COLOR: blue;">LanSwitch</span></font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">是二层交换设备，它可以理解二层网络协议地址</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">MAC</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址。二层交换机在操作过程中不断的收集资料去建立它本身的地址表，这个表相当简单，主要标明某个</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">MAC</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址是在哪个端口上被发现的，所以当交换机接收到一个数据封包时，它会检查该封包的目的</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">MAC</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址，核对一下自己的地址表以决定从哪个端口发送出去。而不是象</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">HUB</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">那样，任何一个发方数据都会出现在</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">HUB</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">的所有端口上</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">(</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">不管是否为你所需</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">)</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">。这样，</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">LanSwitch</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">在提高效率的同时，也提高了系统的安全性。</span><span lang="EN-US" style="COLOR: blue;"><p></p></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">接下来的一年，岳不群大量招收门徒，华山派得以极大的壮大，所使用的</span><span lang="EN-US"><font face="Times New Roman">LanSwitch</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">也多次级连。但门徒中难免鱼龙混杂，当时华山派一批三、四代弟子崇拜万里独行田伯光，成立了一个田协，经常广播争论比赛八百米还是一千米很合理的问题；第三代弟子中有一个叫李洪志的，每天在华山派内部广播法轮大法；更让令狐冲受不了的是，随着师父年龄的增大，变得越来越罗嗦，每句话都要重复二十遍，然后在网上广播。令狐冲想和小师妹、陆大有等人专门使用一个广播域，但如果另外使用一个</span><span lang="EN-US"><font face="Times New Roman">LanSwitch</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">的话，师父肯定不会同意，于是，他修改了</span><span lang="EN-US"><font face="Times New Roman">LanSwitch</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">的App，把小师妹、陆大有等人和自己划成一个虚拟网</span><span lang="EN-US"><font face="Times New Roman">(VLAN)</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，其它人使用另外的</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，广播包只在</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">内发送，</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">间通过路由器连接。岳不群也深受田协、李洪志其害，但为与左冷禅抗争，用人之际，只能隐忍，知道了这件事，大为高兴，但仍为令狐冲私自修改App一事，罚他到思过崖面壁一年，一年之内不得下山。</span><font face="Times New Roman">
                        </font><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">岳不群在华山派内重新使用</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">进行子网划分，分为五个子网，师父和师娘、小师妹还有林平之在一个</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，法轮功弟子用一个</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，田协弟子用一个</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，其它弟子用一个</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，而思过崖上也有单独的一个</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">。令狐冲到了思过崖，并不难过，终于，世界安静了，依靠左冷禅的路由器，令狐冲还可以每天在网上给小师妹讲故事，聊天。</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">局域网交换机的引入，使得网络节点间可独享带宽，但是，对于二层广播报文，二层交换机会在各网络节点上进行广播；同时，对于二层交换机无法识别的</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">MAC</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址，也必须在广播域内进行广播。当多个二层交换机级连时，二层交换网络上的所有设备都会收到广播消息。在一个大型的二层广播域内，大量的广播使二层转发的效率减低，为了避免在大型交换机上进行的广播所引起的广播风暴，需要在一个二层交换网络内进一步划分为多个虚拟网</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">(VLAN)</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">。在一个虚拟网</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">(VLAN)</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">内，由一个工作站发出的信息只能发送到具有相同虚拟网号</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">(VLANID)</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">的其他站点，其它虚拟网</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">(VLAN)</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">的成员收不到这些信息或广播帧。采用虚拟网</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">(VLAN)</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">可以控制网络上的广播风暴和增加网络的安全性。不同虚拟网</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">(VLAN)</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">之间的通信必须通过路由器进行。</span><span lang="EN-US" style="COLOR: blue;"><p></p></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">但是幸福永远是短暂的，接下来总是无尽的烦恼。随着整个五岳剑派势力的增大，路由器的速度越来越慢。令狐冲发现每次给小师妹讲故事时，小师妹的回答总是姗姗来迟，而且话也很少，总是</span><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">嗯</span><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，</span><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">噢</span><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">或者</span><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">我听着呢</span><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">。终于有一天，路由器再也</span><span lang="EN-US"><font face="Times New Roman">ING</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">不通的，令狐冲三天没有得到小师妹的消息，对着空空的显示屏，再也忍不住，在一个下着雪的晚上，偷偷下山找小师妹，到了小师妹窗前，发现小师妹正在网上和小林子热烈的聊天，全没注意一边的自己，内心一阵酸痛，回到思过崖，大病一场。病好后潜心研究，终于有一天，做出来一个路由器，这时，令狐冲发现，此时华山派已经有了三十个</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，路由器必须为每个</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">分配一个接口，接口不够用，而且，两个子网内通过路由器的交换速度远远低于二层交换的速度。</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US" style="COLOR: blue;"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">二层交换机划分虚拟子网后，就出现了一个问题：不同虚拟子网之间的转发需要通过其它路由器来实现。二层交换机的不同</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">VLAN</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">节点间的转发需要通过路由器设备来实现浪费了端口，而路由器的高成本，低效率又使它无法满足大量子网情况下的三层转发需求，三层交换的概念就在这种情况下被提了出来。</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">这天晚上，令狐冲心灰意懒，借酒消愁，这时，一个黑影出现在他的面前，原来是一个仙风道骨的老人，正是风清扬。风清扬听了令狐冲的疑惑，说：路由器接口不够，把路由器做在</span><span lang="EN-US"><font face="Times New Roman">LanSwitch</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">内部不就可以了；交换速度慢，是因为路由器查找的是网段路由，而</span><span lang="EN-US"><font face="Times New Roman">LanSwitch</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">直接查</span><span lang="EN-US"><font face="Times New Roman">MAC</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">对应出端口，当然速度快。为什么不能直接根据</span><span lang="EN-US"><font face="Times New Roman">IP</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址查到出端口呢？令狐冲一听，大为仰慕，但还是不明白，</span><span lang="EN-US"><font face="Times New Roman">IP</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址那么多，而且经常变化，如何能够直接查到出端口呢？风清扬说：</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">你先坐下，让我来问你，华山派有多少弟子？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">一万六千左右。</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">你全知道他们住哪里吗？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">不知道。</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">岳不群要你找一个不知道住哪里的人，如何去找？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">查华山派电话号码查询系统，找到他的地址，然后去找他。</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">如果你回来后再让你找这个人，又如何去找？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">如何</span><span lang="EN-US"><font face="Times New Roman">.... </font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，查华山派电话号码查询系统，找到他的地址，然后去找他。</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">你不知道到这个人的地址吗？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">知道，但师父说，华山派的地址那么多，而且经常变化，不用知道地址。</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">岳不群这小子，把徒弟都教成木头了！我问你，你自己认为应该如何找？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">直接去找！</span></font><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"<br/>"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">好！你这人还不算太苯。那你知道了一个人的地址后，是不是永远记住了？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">有的人记住了。其它的都忘了。</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">为什么忘了？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">因为我记不了那么多人，而且一段时间没有去找他。</span></font><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"<br/>"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">华山派电话号码查询系统里的地址是如何获得的？</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">我在空旷处大喊一声他的名字，他听到后就会来找我，告诉我他的地址。</span><span lang="EN-US"><font face="Times New Roman">"</font></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">风清扬又问了大把类似脑筋急转弯的问题，然后风清扬说：</span><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">现在你明白根据</span><span lang="EN-US"><font face="Times New Roman">IP</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址直接查出端口的道理了吗？等到你明白这个道理，你自然会做出三层交换机来</span><span lang="EN-US"><font face="Times New Roman">"</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，令狐冲仔细回忆了今天的话，终于明白了和二层转发由</span><span lang="EN-US"><font face="Times New Roman">MAC</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址对应到出端口的道理一样，三层转发也可以直接由</span><span lang="EN-US"><font face="Times New Roman">IP</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址对应到出端口，</span><span lang="EN-US"><font face="Times New Roman">IP</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址的路由可以通过</span><span lang="EN-US"><font face="Times New Roman">ARP</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">来学习，同样需要老化。这样，</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">间转发除第一个包需要通过</span><span lang="EN-US"><font face="Times New Roman">ARP</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">获得主机路由外，其它的报文直接根据</span><span lang="EN-US"><font face="Times New Roman">IP</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">地址就能够查找到出端口，转发速度远远高于路由器转发的速度。抬头看时，风清扬已经走了。</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">一年后，令狐冲下思过崖，成功的推出三层交换机，实现了</span><span lang="EN-US"><font face="Times New Roman">VLAN</font></span><span style="FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">间的互通，并且与嵩山，黑木崖等路由器实现互通。</span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">三层交换机是在二层交换机的基础上增加三层交换功能，但它不是简单的二层交换机加路由器，二而是采用了不同的转发机制。路由器的转发采用最长匹配的方式，实现复杂，通常使用App来实现；而三层交换机的路由查找是针对流的，它利用</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">CACHE</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">技术，很容易采用</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">ASIC</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">实现，因此，可以的节约成本，并实现快速转发。</span><span lang="EN-US" style="COLOR: blue;"><p></p></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US" style="COLOR: blue;"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">很多文章会提及三层交换机和路由器的区别，一般的比较是三层交换机又快又便宜。这些话没有错，但场合是汇聚层。大家看到，在汇聚层，面向三层交换机直接下挂的主机，因为能够获得其主机路由，所以三层交换机能够实现快速查找；而对于通过其它路由器连接多个子网后到达的主机，三层交换机和路由器的处理是一样的，同样采用最长匹配的方法查找到下一跳，由下一跳路由器进行转发。</span><span lang="EN-US" style="COLOR: blue;"><p></p></span></font></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><font color="#3333cc"><span lang="EN-US" style="COLOR: blue;"><span style="mso-spacerun: yes;"><font face="Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></span></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">因此，通常的组网方式是在骨干层使用</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">GSR</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">，汇聚层使用三层交换机。当然，对于一个小型的城域网，也可以直接拿三层交换机组网，不需要</span><span lang="EN-US" style="COLOR: blue;"><font face="Times New Roman">GSR</font></span><span style="COLOR: blue; FONT-FAMILY: 宋体; mso-hansi-font-family: &quot;Times New Roman&quot;;">。</span><span lang="EN-US" style="COLOR: blue;"><p></p></span></font></p>