于废墟之中升起灯塔https://www.linglog.cc/Firefly6.10.3https://github.com/CuteLeaf/Firefly2026年5月16日 20:55:40https://www.linglog.cc/posts/day_5/https://www.linglog.cc/posts/day_5/这篇日记，诞生于网站建成当晚的瓢泼大雨之中。Sat, 16 May 2026 00:00:00 GMT<section><h1>欲买桂花同载酒，终不似，少年游。<a href="#欲买桂花同载酒终不似少年游"><span>#</span></a></h1><p><em>喝酒我只在开心的时候喝，不开心的时候就不喝</em></p><hr /><section><h2>作者有话说<a href="#作者有话说"><span>#</span></a></h2><p>今天是我开站的第一天，它也是我开站的第一篇日记，你问我之前的日记算什么？</p><p>那些都是在我建立网站之前写的，所以不算，我只是把我之前的日记迁移了一下，嗯，因为有隐私，所以我隐藏了，嘿嘿，不过，只要你看过灵笼，你应该是知道密码的，我大部分日记都可以看，除了个别的</p><p>不过个别的，我密码也不一样，你能猜到嘛</p></section><section><h2>今天怎么样？<a href="#今天怎么样"><span>#</span></a></h2><p>今天下雨了，这几天都有雨，虽然我不是很喜欢下雨，但是下雨也是有好处的，会变得凉快，我喜欢舒适的温度，而不是极端的温度，hh</p><p>今天我是上午去看了看招聘会，感觉没啥好看的，不过还是有一些不错的岗位，比如说内个船员就不错，向大海启航！</p><p>看完了招聘会，我就去吃饭了，吃完了饭，我就回来了，emm，然后我一下午就都在弄我的小网站，我决定今天把它搞定，虽然我还有好多没弄呢</p></section><section><h2>晚上吃啥呢<a href="#晚上吃啥呢"><span>#</span></a></h2><p>吃牛肉拉面！ (其实我吃的是西红柿鸡蛋面)</p></section><section><h2>小计划<a href="#小计划"><span>#</span></a></h2><p>今天我要把网站搞定，再把老师的笔记都放到我的网站上面。</p></section></section>https://www.linglog.cc/posts/day_4/https://www.linglog.cc/posts/day_4/之前写的日记Tue, 12 May 2026 00:00:00 GMT本文已加密保护，请访问网站查看。https://www.linglog.cc/posts/h3c/https://www.linglog.cc/posts/h3c/一些 H3C 交换机常用命令与配置速查Wed, 06 May 2026 00:00:00 GMT<section><h2>一、系统基础<a href="#一系统基础"><span>#</span></a></h2><div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><div>1</div></div><div><span>system-view</span><span> </span><span>//</span><span> </span><span>进入系统视图</span></div></div><div><div><div>2</div></div><div><span>sysname</span><span> </span><span>SW1-Group4</span><span> </span><span>//</span><span> </span><span>修改设备名称</span></div></div><div><div><div>3</div></div><div> </div></div><div><div><div>4</div></div><div><span>save</span><span> </span><span>//</span><span> </span><span>保存配置</span></div></div><div><div><div>5</div></div><div><span>reboot</span><span> </span><span>//</span><span> </span><span>重启设备</span></div></div><div><div><div>6</div></div><div> </div></div><div><div><div>7</div></div><div><span>undo</span><span> </span><span>shutdown</span><span> </span><span>//</span><span> </span><span>开启接口</span></div></div><div><div><div>8</div></div><div> </div></div><div><div><div>9</div></div><div><span>display</span><span> </span><span>current-configuration</span><span> </span><span>//</span><span> </span><span>查看当前配置（dis</span><span> </span><span>cu）</span></div></div><div><div><div>10</div></div><div><span>display</span><span> </span><span>saved-configuration</span><span> </span><span>//</span><span> </span><span>查看已保存配置</span></div></div></code></pre><div><div></div><div></div></div></figure></div><hr /></section> <section><h2>二、VLAN 与接口配置<a href="#二vlan-与接口配置"><span>#</span></a></h2><div><div><div><figure><figcaption><span></span><span>Terminal window</span><span>展开</span><span>收起</span></figcaption><pre><code><div><div><div>1</div></div><div><span>vlan</span><span> </span><span>40</span></div></div><div><div><div>2</div></div><div><span> </span><span>name</span><span> </span><span>Group4-PC-VLAN</span><span> </span><span>//</span><span> </span><span>VLAN</span><span> </span><span>命名（可选）</span></div></div><div><div><div>3</div></div><div> </div></div><div><div><div>4</div></div><div><span>interface</span><span> </span><span>GigabitEthernet</span><span> </span><span>1/0/1</span></div></div><div><div><div>5</div></div><div><span> </span><span>port</span><span> </span><span>link-type</span><span> </span><span>access</span></div></div><div><div><div>6</div></div><div><span> </span><span>port</span><span> </span><span>access</span><span> </span><span>vlan</span><span> </span><span>40</span></div></div><div><div><div>7</div></div><div> </div></div><div><div><div>8</div></div><div><span>interface</span><span> </span><span>GigabitEthernet</span><span> </span><span>1/0/24</span></div></div><div><div><div>9</div></div><div><span> </span><span>port</span><span> </span><span>link-type</span><span> </span><span>trunk</span></div></div><div><div><div>10</div></div><div><span> </span><span>port</span><span> </span><span>trunk</span><span> </span><span>permit</span><span> </span><span>vlan</span><span> </span><span>40</span></div></div><div><div><div>11</div></div><div><span> </span><span>port</span><span> </span><span>trunk</span><span> </span><span>pvid</span><span> </span><span>vlan</span><span> </span><span>1</span></div></div><div><div><div>12</div></div><div> </div></div><div><div><div>13</div></div><div><span>display</span><span> </span><span>vlan</span></div></div><div><div><div>14</div></div><div><span>display</span><span> </span><span>vlan</span><span> </span><span>brief</span></div></div><div><div><div>15</div></div><div><span>display</span><span> </span><span>port</span><span> </span><span>vlan</span></div></div><div><div><div>16</div></div><div><span>display</span><span> </span><span>mac-address</span></div></div></code></pre><div><div></div><div></div></div></figure><div></div></div><span>展开</span><span>收起</span></div></div><hr /></section> <section><h2>三、三层接口与网关<a href="#三三层接口与网关"><span>#</span></a></h2><div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><div>1</div></div><div><span>interface</span><span> </span><span>Vlan-interface</span><span> </span><span>40</span></div></div><div><div><div>2</div></div><div><span> </span><span>ip</span><span> </span><span>address</span><span> </span><span>10.0.4.254</span><span> </span><span>255.255.255.0</span></div></div><div><div><div>3</div></div><div> </div></div><div><div><div>4</div></div><div><span>interface</span><span> </span><span>GigabitEthernet</span><span> </span><span>1/0/24</span></div></div><div><div><div>5</div></div><div><span> </span><span>undo</span><span> </span><span>portswitch</span><span> </span><span>//</span><span> </span><span>切换为三层接口</span></div></div><div><div><div>6</div></div><div><span> </span><span>ip</span><span> </span><span>address</span><span> </span><span>10.99.0.2</span><span> </span><span>255.255.255.252</span></div></div><div><div><div>7</div></div><div> </div></div><div><div><div>8</div></div><div><span>display</span><span> </span><span>ip</span><span> </span><span>interface</span><span> </span><span>brief</span></div></div><div><div><div>9</div></div><div><span>display</span><span> </span><span>interface</span><span> </span><span>brief</span></div></div><div><div><div>10</div></div><div><span>display</span><span> </span><span>arp</span><span> </span><span>all</span></div></div></code></pre><div><div></div><div></div></div></figure></div><hr /></section> <section><h2>四、静态路由<a href="#四静态路由"><span>#</span></a></h2><div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><div>1</div></div><div><span>ip</span><span> </span><span>route-static</span><span> </span><span>0.0.0.0</span><span> </span><span>0.0.0.0</span><span> </span><span>10.99.0.1</span></div></div><div><div><div>2</div></div><div><span>ip</span><span> </span><span>route-static</span><span> </span><span>10.0.1.0</span><span> </span><span>255.255.255.0</span><span> </span><span>10.99.0.1</span></div></div><div><div><div>3</div></div><div><span>ip</span><span> </span><span>route-static</span><span> </span><span>10.0.2.0</span><span> </span><span>24</span><span> </span><span>10.99.0.1</span></div></div><div><div><div>4</div></div><div> </div></div><div><div><div>5</div></div><div><span>display</span><span> </span><span>ip</span><span> </span><span>routing-table</span></div></div><div><div><div>6</div></div><div> </div></div><div><div><div>7</div></div><div><span>ping</span><span> </span><span>10.99.0.1</span></div></div><div><div><div>8</div></div><div><span>tracert</span><span> </span><span>10.0.1.254</span></div></div></code></pre><div><div></div><div></div></div></figure></div><hr /></section> <section><h2>五、单臂路由<a href="#五单臂路由"><span>#</span></a></h2><div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><div>1</div></div><div><span>interface</span><span> </span><span>GigabitEthernet</span><span> </span><span>1/0/1.10</span></div></div><div><div><div>2</div></div><div><span> </span><span>vlan-type</span><span> </span><span>dot1q</span><span> </span><span>vid</span><span> </span><span>10</span></div></div><div><div><div>3</div></div><div><span> </span><span>ip</span><span> </span><span>address</span><span> </span><span>192.168.10.254</span><span> </span><span>255.255.255.0</span></div></div></code></pre><div><div></div><div></div></div></figure></div><hr /></section> <section><h2>六、SSH 远程管理<a href="#六ssh-远程管理"><span>#</span></a></h2><div><div><div><figure><figcaption><span></span><span>Terminal window</span><span>展开</span><span>收起</span></figcaption><pre><code><div><div><div>1</div></div><div><span>public-key</span><span> </span><span>local</span><span> </span><span>create</span><span> </span><span>rsa</span><span> </span><span>//</span><span> </span><span>首次配置需生成</span><span> </span><span>RSA</span><span> </span><span>密钥</span></div></div><div><div><div>2</div></div><div><span>ssh</span><span> </span><span>server</span><span> </span><span>enable</span></div></div><div><div><div>3</div></div><div> </div></div><div><div><div>4</div></div><div><span>local-user</span><span> </span><span>admin</span><span> </span><span>class</span><span> </span><span>manage</span></div></div><div><div><div>5</div></div><div><span> </span><span>password</span><span> </span><span>simple</span><span> </span><span>Xgxy@2026</span></div></div><div><div><div>6</div></div><div><span> </span><span>service-type</span><span> </span><span>ssh</span></div></div><div><div><div>7</div></div><div><span> </span><span>authorization-attribute</span><span> </span><span>user-role</span><span> </span><span>level-15</span></div></div><div><div><div>8</div></div><div> </div></div><div><div><div>9</div></div><div><span>user-interface</span><span> </span><span>vty</span><span> </span><span>0</span><span> </span><span>4</span></div></div><div><div><div>10</div></div><div><span> </span><span>authentication-mode</span><span> </span><span>scheme</span></div></div><div><div><div>11</div></div><div><span> </span><span>protocol</span><span> </span><span>inbound</span><span> </span><span>ssh</span></div></div><div><div><div>12</div></div><div><span> </span><span>idle-timeout</span><span> </span><span>10</span><span> </span><span>0</span></div></div><div><div><div>13</div></div><div> </div></div><div><div><div>14</div></div><div><span>display</span><span> </span><span>ssh</span><span> </span><span>server</span><span> </span><span>status</span></div></div><div><div><div>15</div></div><div><span>display</span><span> </span><span>users</span></div></div></code></pre><div><div></div><div></div></div></figure><div></div></div><span>展开</span><span>收起</span></div></div><hr /></section> <section><h2>七、ACL 基础<a href="#七acl-基础"><span>#</span></a></h2><div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><div>1</div></div><div><span>acl</span><span> </span><span>basic</span><span> </span><span>2000</span></div></div><div><div><div>2</div></div><div><span> </span><span>rule</span><span> </span><span>permit</span><span> </span><span>source</span><span> </span><span>10.0.4.0</span><span> </span><span>0.0.0.255</span></div></div><div><div><div>3</div></div><div> </div></div><div><div><div>4</div></div><div><span>acl</span><span> </span><span>advanced</span><span> </span><span>3000</span></div></div><div><div><div>5</div></div><div><span> </span><span>rule</span><span> </span><span>deny</span><span> </span><span>tcp</span><span> </span><span>source</span><span> </span><span>any</span><span> </span><span>destination</span><span> </span><span>any</span><span> </span><span>destination-port</span><span> </span><span>eq</span><span> </span><span>80</span></div></div><div><div><div>6</div></div><div> </div></div><div><div><div>7</div></div><div><span>interface</span><span> </span><span>GigabitEthernet</span><span> </span><span>1/0/1</span></div></div><div><div><div>8</div></div><div><span> </span><span>packet-filter</span><span> </span><span>3000</span><span> </span><span>inbound</span></div></div><div><div><div>9</div></div><div> </div></div><div><div><div>10</div></div><div><span>display</span><span> </span><span>acl</span><span> </span><span>all</span></div></div></code></pre><div><div></div><div></div></div></figure></div><hr /></section> <section><h2>八、常用查看命令速记<a href="#八常用查看命令速记"><span>#</span></a></h2><div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><div>1</div></div><div><span>dis</span><span> </span><span>cu</span><span> | </span><span>inc</span><span> </span><span>vlan</span><span> </span><span>//</span><span> </span><span>查看</span><span> </span><span>VLAN</span><span> </span><span>相关配置</span></div></div><div><div><div>2</div></div><div> </div></div><div><div><div>3</div></div><div><span>dis</span><span> </span><span>int</span><span> </span><span>br</span><span> </span><span>//</span><span> </span><span>接口状态</span></div></div><div><div><div>4</div></div><div><span>dis</span><span> </span><span>ip</span><span> </span><span>int</span><span> </span><span>br</span><span> </span><span>//</span><span> </span><span>IP</span><span> </span><span>地址表</span></div></div><div><div><div>5</div></div><div> </div></div><div><div><div>6</div></div><div><span>dis</span><span> </span><span>ip</span><span> </span><span>rou</span><span> </span><span>//</span><span> </span><span>路由表</span></div></div><div><div><div>7</div></div><div><span>dis</span><span> </span><span>mac-add</span><span> </span><span>//</span><span> </span><span>MAC</span><span> </span><span>地址表</span></div></div><div><div><div>8</div></div><div><span>dis</span><span> </span><span>arp</span><span> </span><span>//</span><span> </span><span>ARP</span><span> </span><span>表</span></div></div><div><div><div>9</div></div><div><span>dis</span><span> </span><span>vlan</span><span> </span><span>//</span><span> </span><span>VLAN</span><span> </span><span>信息</span></div></div><div><div><div>10</div></div><div> </div></div><div><div><div>11</div></div><div><span>ping</span><span> </span><span>-a</span><span> </span><span>10.0.4.254</span><span> </span><span>10.0.1.1</span></div></div></code></pre><div><div></div><div></div></div></figure></div></section>https://www.linglog.cc/posts/day_3/https://www.linglog.cc/posts/day_3/之前写的日记Sat, 02 May 2026 00:00:00 GMT本文已加密保护，请访问网站查看。https://www.linglog.cc/posts/day_2/https://www.linglog.cc/posts/day_2/之前写的日记Sun, 26 Apr 2026 00:00:00 GMT本文已加密保护，请访问网站查看。https://www.linglog.cc/posts/day_1/https://www.linglog.cc/posts/day_1/这是我之前的第一个的日记Fri, 24 Apr 2026 00:00:00 GMT本文已加密保护，请访问网站查看。https://www.linglog.cc/posts/%E5%85%89%E7%BA%A4%E7%AC%94%E8%AE%B0/https://www.linglog.cc/posts/%E5%85%89%E7%BA%A4%E7%AC%94%E8%AE%B0/一些关于光纤、光模块与实际网络场景的学习记录Fri, 24 Apr 2026 00:00:00 GMT<section><h1>光纤知识补充<a href="#光纤知识补充"><span>#</span></a></h1><p>记录一些学习网络运维时顺手整理的光纤知识。</p><hr /></section> <section><h1>一、光纤基本结构<a href="#一光纤基本结构"><span>#</span></a></h1><ul> <li> <p><strong>纤芯（Core）</strong></p> <ul> <li>用于传输光信号</li> <li>材料一般为高纯度二氧化硅</li> </ul> </li> <li> <p><strong>包层（Cladding）</strong></p> <ul> <li>折射率略低于纤芯</li> <li>使光在线芯内发生全反射</li> </ul> </li> <li> <p><strong>涂覆层（Coating）</strong></p> <ul> <li>用于保护光纤</li> <li>常见材料为丙烯酸树脂</li> </ul> </li> <li> <p><strong>护套（Jacket）</strong></p> <ul> <li>最外层保护结构</li> <li>不同颜色通常代表不同类型</li> </ul> </li> </ul><hr /></section> <section><h1>二、单模（SMF）与多模（MMF）<a href="#二单模smf与多模mmf"><span>#</span></a></h1> <table><thead><tr><th>对比项</th><th>单模光纤（SMF）</th><th>多模光纤（MMF）</th></tr></thead><tbody><tr><td>纤芯直径</td><td>约 9 μm</td><td>50 μm / 62.5 μm</td></tr><tr><td>光源</td><td>激光（LD）</td><td>LED / VCSEL</td></tr><tr><td>典型波长</td><td>1310 nm / 1550 nm</td><td>850 nm / 1300 nm</td></tr><tr><td>传输距离</td><td>几公里 ~ 上百公里</td><td>几百米</td></tr><tr><td>带宽</td><td>极高，模态色散极低</td><td>受模态色散限制</td></tr><tr><td>外皮颜色</td><td>黄色</td><td>橙色 / 水蓝色</td></tr><tr><td>常见标准</td><td>OS1 / OS2</td><td>OM1 ~ OM5</td></tr><tr><td>典型场景</td><td>城域网、骨干网</td><td>数据中心、机房内部</td></tr><tr><td>光模块成本</td><td>较高</td><td>相对便宜</td></tr></tbody></table><hr /><section><h2>注意事项<a href="#注意事项"><span>#</span></a></h2><p>单模与多模模块不能混用。</p><p>因为：</p><ul> <li>纤芯规格不同</li> <li>光源类型不同</li> <li>波长不同</li> </ul><p>容易导致：</p><ul> <li>光损耗巨大</li> <li>无法通信</li> <li>光功率异常</li> </ul><hr /></section></section> <section><h1>三、多模光纤演进<a href="#三多模光纤演进"><span>#</span></a></h1> <table><thead><tr><th>标准</th><th>特点</th><th>常见场景</th></tr></thead><tbody><tr><td>OM1</td><td>62.5 μm，较老</td><td>legacy 系统</td></tr><tr><td>OM2</td><td>50 μm</td><td>老设备兼容</td></tr><tr><td>OM3</td><td>激光优化</td><td>万兆数据中心主流</td></tr><tr><td>OM4</td><td>更高带宽</td><td>40G / 100G</td></tr><tr><td>OM5</td><td>支持 SWDM</td><td>面向高速演进</td></tr></tbody></table><hr /></section> <section><h1>四、常见光纤接口<a href="#四常见光纤接口"><span>#</span></a></h1> <table><thead><tr><th>接口</th><th>特点</th><th>场景</th></tr></thead><tbody><tr><td>LC</td><td>小型化、卡扣式</td><td>最主流</td></tr><tr><td>SC</td><td>方形、推拉式</td><td>光猫、运营商</td></tr><tr><td>FC</td><td>螺纹锁紧</td><td>测试仪器</td></tr><tr><td>ST</td><td>卡口旋转式</td><td>老设备</td></tr><tr><td>MPO/MTP</td><td>多芯一体</td><td>高密度数据中心</td></tr><tr><td>E2000</td><td>带防尘盖</td><td>电信级场景</td></tr></tbody></table><hr /></section> <section><h1>五、跳线类型<a href="#五跳线类型"><span>#</span></a></h1><ul> <li> <p><strong>Simplex（单工）</strong></p> <ul> <li>单根光纤</li> <li>单向传输</li> </ul> </li> <li> <p><strong>Duplex（双工）</strong></p> <ul> <li>两根光纤</li> <li>一收一发</li> </ul> </li> <li> <p><strong>单芯 / 双芯</strong></p> <ul> <li>单芯通常配合 BIDI 光模块</li> <li>使用不同波长实现同时收发</li> </ul> </li> </ul><hr /></section> <section><h1>六、光纤损耗与衰减<a href="#六光纤损耗与衰减"><span>#</span></a></h1> <table><thead><tr><th>因素</th><th>说明</th></tr></thead><tbody><tr><td>固有衰减</td><td>光在玻璃中的吸收与散射</td></tr><tr><td>弯曲损耗</td><td>过度弯折导致漏光</td></tr><tr><td>连接损耗</td><td>法兰盘、熔接点引入损耗</td></tr><tr><td>脏污损耗</td><td>端面灰尘是现场故障高发原因</td></tr></tbody></table><hr /><section><h2>链路预算<a href="#链路预算"><span>#</span></a></h2><p>经验公式：</p><div><figure><figcaption></figcaption><pre><code><div><div><div>1</div></div><div><span>总损耗 = 光纤衰减 + 接头损耗 + 预留余量</span></div></div></code></pre><div><div></div><div></div></div></figure></div><p>通常会额外预留约 3 dB。</p><hr /></section></section> <section><h1>七、色散<a href="#七色散"><span>#</span></a></h1> <table><thead><tr><th>类型</th><th>影响</th><th>应对方式</th></tr></thead><tbody><tr><td>模态色散</td><td>多模传播时间不同</td><td>使用单模或 OM3/OM4</td></tr><tr><td>色度色散</td><td>不同波长速度不同</td><td>色散补偿</td></tr><tr><td>PMD</td><td>高速长距影响明显</td><td>DSP 补偿</td></tr></tbody></table><hr /></section> <section><h1>八、波长窗口<a href="#八波长窗口"><span>#</span></a></h1><ul> <li> <p><strong>850 nm</strong></p> <ul> <li>多模</li> <li>成本低</li> <li>短距离</li> </ul> </li> <li> <p><strong>1310 nm</strong></p> <ul> <li>单模常用</li> <li>中短距离</li> </ul> </li> <li> <p><strong>1550 nm</strong></p> <ul> <li>衰减最低</li> <li>长距离主流</li> </ul> </li> <li> <p><strong>1490 / 1577 nm</strong></p> <ul> <li>常用于 PON 网络</li> </ul> </li> </ul><hr /></section> <section><h1>九、光模块与光纤对应关系<a href="#九光模块与光纤对应关系"><span>#</span></a></h1> <table><thead><tr><th>模块类型</th><th>光纤</th><th>典型距离</th><th>场景</th></tr></thead><tbody><tr><td>SX</td><td>多模</td><td>几百米</td><td>千兆短距</td></tr><tr><td>LX</td><td>单模</td><td>10 km</td><td>千兆长距</td></tr><tr><td>EX / ZX</td><td>单模</td><td>40 / 80 km</td><td>长距离</td></tr><tr><td>BIDI</td><td>单芯单模</td><td>10 ~ 40 km</td><td>单纤双向</td></tr><tr><td>CWDM / DWDM</td><td>单模</td><td>超长距</td><td>波分复用</td></tr><tr><td>SR</td><td>多模</td><td>100 ~ 300 m</td><td>10G/25G</td></tr><tr><td>LR</td><td>单模</td><td>10 km</td><td>长距</td></tr><tr><td>ER / ZR</td><td>单模</td><td>40 / 80 km</td><td>超长距</td></tr></tbody></table><hr /></section> <section><h1>十、施工与维护<a href="#十施工与维护"><span>#</span></a></h1> <table><thead><tr><th>项目</th><th>说明</th></tr></thead><tbody><tr><td>熔接</td><td>损耗最低</td></tr><tr><td>冷接</td><td>适合应急</td></tr><tr><td>弯曲半径</td><td>避免过度弯折</td></tr><tr><td>端面清洁</td><td>禁止手擦、嘴吹</td></tr><tr><td>APC / UPC</td><td>不能混接</td></tr><tr><td>红光笔（VFL）</td><td>查断点神器</td></tr><tr><td>OTDR</td><td>测链路衰减与故障</td></tr></tbody></table><hr /></section> <section><h1>十一、快速记忆口诀<a href="#十一快速记忆口诀"><span>#</span></a></h1><blockquote><p>单模细芯跑长途，黄色外皮激光输；<br /> 多模粗芯跑短途，橙蓝外皮 LED 足；<br /> LC 小扣最常见，SC 方头运营商见；<br /> 端面脏了损耗大，清洁别用手去擦；<br /> APC 斜角 UPC 平，混接一定会出情。</p></blockquote><hr /></section> <section><h1>十二、额外补充<a href="#十二额外补充"><span>#</span></a></h1><section><h2>LED 与 LD<a href="#led-与-ld"><span>#</span></a></h2> <table><thead><tr><th>光源</th><th>特点</th><th>适用场景</th></tr></thead><tbody><tr><td>LED</td><td>成本低、发散角大</td><td>多模短距离</td></tr><tr><td>LD（激光二极管）</td><td>功率高、光谱窄</td><td>单模长距离</td></tr></tbody></table><hr /></section><section><h2>UPC 与 APC<a href="#upc-与-apc"><span>#</span></a></h2><section><h3>UPC<a href="#upc"><span>#</span></a></h3><ul> <li>Ultra Physical Contact</li> <li>微凸球面</li> <li>回波损耗约 -55 dB</li> </ul><p>特点：</p><ul> <li>接近平面</li> <li>常规场景最常见</li> </ul><hr /></section><section><h3>APC<a href="#apc"><span>#</span></a></h3><ul> <li>Angled Physical Contact</li> <li>8° 斜角端面</li> <li>回波损耗低于 -60 dB</li> </ul><p>特点：</p><ul> <li>反射光不会原路返回</li> <li>常用于 PON / CATV</li> </ul><hr /></section></section><section><h2>注意<a href="#注意"><span>#</span></a></h2><p>APC 与 UPC 不能混接。</p><p>否则：</p><ul> <li>损耗会明显升高</li> <li>容易导致链路异常</li> </ul></section></section>