.. 标题：VLAN 和 802.1Q 集群分析仪
.. slug：vlan-trunking-analyzer
.. 日期: 2026-03-27 12:00:00 世界标准时间
..标签：网络、vlan、802.1q、计算器、工具
..类别：计算器
..链接：
..描述：计算802.1Q中继开销，解析VLAN允许列表，并规划QinQ双标签MTU对网络中继设计的影响。
..类型：文本
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<div class="calc-container">
<div class="calc-header">
<h2>VLAN 和 802.1Q 集群分析仪</h2>
<p>解析VLAN允许列表，计算标签开销，并规划QinQ MTU影响。</p>
</div>
第 1 部分：VLAN 允许列表解析器
<div class="result-section">
<div class="section-header">VLAN 允许列表解析器</div>
<div class="section-content">
<div class="input-grid">
<div class="input-group" style="grid-column:1/-1">
<label>VLAN 列表（例如 1-10,20,100-200,4094）</label>
<input id="vlanList" placeholder="1-10,20,100-200,4094" type="text" value="1-10,20,100-200,4094"/>
</div>
</div>
<div class="button-container" style="justify-content:flex-start;margin-top:12px">
<button class="calc-button" onclick="parseVlanList()">解析</button>
</div>
<div id="vlanResult" style="display:none;margin-top:15px"></div>
</div>
</div>
第 2 部分：802.1Q 标签开销计算器
<div class="result-section">
<div class="section-header">802.1Q 标签开销计算器</div>
<div class="section-content">
<div class="input-grid">
<div class="input-group">
<label>基本 MTU（字节）</label>
<input id="baseMtu" max="9216" min="64" type="number" value="1500"/>
</div>
<div class="input-group">
<label>标签模式</label>
<select id="tagMode">
<option value="untagged">未标记（无开销）</option>
<option selected="" value="dot1q">802.1Q（单标签，+4字节）</option>
<option value="qinq">QiQ / 802.1ad（双标签，+8字节）</option>
</select>
</div>
<div class="input-group">
<label>链接速度 (Gbps)</label>
<select id="linkSpeed">
<option value="1">1 Gbps</option>
<option selected="" value="10">10Gbps</option>
<option value="25">25Gbps</option>
<option value="40">40Gbps</option>
<option value="100">100Gbps</option>
<option value="400">400Gbps</option>
</select>
</div>
</div>
<div class="button-container" style="justify-content:flex-start;margin-top:12px">
<button class="calc-button" onclick="calcOverhead()">计算</button>
</div>
<div id="overheadResult" style="display:none;margin-top:15px"></div>
</div>
</div>
第 3 节：QinQ / 802.1ad 标签字节布局参考
<div class="result-section">
<div class="section-header">QiQ/802.1ad双标签规划</div>
<div class="section-content">
<table>
<tr><th>框架类型</th><th>标签字节</th><th>以太类型</th><th>添加字段</th></tr>
<tr><td>未标记 802.3</td><td>0</td><td>—</td><td>—</td></tr>
<tr><td>802.1Q（点1q）</td><td>+4</td><td>0x8100</td><td>TPID (2) + TCI: PCP(3) + DEI(1) + VID(12)</td></tr>
<tr><td>秦Q/802.1ad</td><td>+8</td><td>0x88A8 外层</td><td>外部标签 (4) + 内部 802.1Q 标签 (4)</td></tr>
</table>
</div>
</div>
</div>
<script>
function expandVlanRange(str) {
    const vlans = new Set();
    str.split(',').forEach(part => {
        part = part.trim();
        if (part.includes('-')) {
            const [start, end] = part.split('-').map(Number);
            if (!isNaN(start) && !isNaN(end) && start <= end && start >= 1 && end <= 4094) {
                for (let v = start; v <= end; v++) vlans.add(v);
            }
        } else {
            const v = parseInt(part);
            if (!isNaN(v) && v >= 1 && v <= 4094) vlans.add(v);
        }
    });
    return Array.from(vlans).sort((a, b) => a - b);
}

function compressVlanList(vlans) {
    if (!vlans.length) return '';
    const ranges = [];
    let start = vlans[0], end = vlans[0];
    for (let i = 1; i < vlans.length; i++) {
        if (vlans[i] === end + 1) { end = vlans[i]; }
        else {
            ranges.push(start === end ? `${start}` : `${start}-${end}`);
            start = end = vlans[i];
        }
    }
    ranges.push(start === end ? `${start}` : `${start}-${end}`);
    return ranges.join(',');
}

function parseVlanList() {
    const input = document.getElementById('vlanList').value;
    const vlans = expandVlanRange(input);
    const div = document.getElementById('vlanResult');
    div.style.display = 'block';
    if (!vlans.length) { div.innerHTML = '<strong style="color:red">No valid VLANs found. Valid range: 1\u20134094.</strong>'; return; }
    const tagsHtml = vlans.slice(0, 100).map(v => `<span class="vlan-tag">${v}</span>`).join('') +
        (vlans.length > 100 ? `<span class="vlan-tag">+${vlans.length - 100} more</span>` : '');
    div.innerHTML = `
        <strong>Count:</strong> ${vlans.length} VLANs<br>
        <strong>Normalized:</strong> <code>${compressVlanList(vlans)}</code><br>
        <strong>Range:</strong> VLAN ${vlans[0]} \u2013 ${vlans[vlans.length - 1]}<br>
        <div class="vlan-tags">${tagsHtml}</div>`;
}

function calcOverhead() {
    const baseMtu = parseInt(document.getElementById('baseMtu').value);
    const div = document.getElementById('overheadResult');
    div.style.display = 'block';
    if (isNaN(baseMtu) || baseMtu < 64 || baseMtu > 9216) {
        div.innerHTML = '<strong style="color:red">Invalid MTU. Enter a value between 64\u20139216 bytes.</strong>';
        return;
    }
    const mode = document.getElementById('tagMode').value;
    const speedGbps = parseFloat(document.getElementById('linkSpeed').value);
    const tagBytes = mode === 'untagged' ? 0 : mode === 'dot1q' ? 4 : 8;
    const effectiveMtu = baseMtu - tagBytes;
    const overheadPct = tagBytes > 0 ? (tagBytes / (baseMtu + tagBytes + 18) * 100).toFixed(3) : 0;
    const throughputLoss = tagBytes > 0
        ? ((tagBytes / (baseMtu + 18 + tagBytes)) * speedGbps).toFixed(4)
        : 0;
    div.innerHTML = `
        <strong>Tag overhead:</strong> ${tagBytes} bytes per frame<br>
        <strong>Effective payload MTU:</strong> ${effectiveMtu} bytes (set this on routed sub-interfaces)<br>
        <strong>Frame overhead:</strong> ${overheadPct}% of wire bandwidth consumed by tag bytes<br>
        <strong>Throughput lost at ${speedGbps} Gbps:</strong> ~${throughputLoss} Gbps<br>
        ${tagBytes > 0 ? `<br><em>Recommendation: If running IP over this trunk, set interface MTU to ${effectiveMtu} to avoid fragmentation, or increase the physical MTU to ${baseMtu + tagBytes} if the switch supports jumbo frames.</em>` : ''}`;
}
</script>