.. titel: VLAN & 802.1Q Trunking Analyzer
.. snigel: vlan-trunking-analyzer
.. datum: 2026-03-27 12:00:00 UTC
.. taggar: nätverk, vlan, 802.1q, kalkylator, verktyg
.. kategori: Miniräknare
..länk:
.. beskrivning: Beräkna 802.1Q-trunk-overhead, analysera VLAN-tillåtna listor och planera QinQ-dubbeltaggar-MTU-påverkan för nätverkstrunkdesign.
.. typ: text
<style>
/* ── CANONICAL DESIGN SYSTEM ─────────────────────────────────────────────── */
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/* ── END CANONICAL ────────────────────────────────────────────────────────── */

.vlan-tag  { background: #4CAF50; color: white; padding: 3px 8px; border-radius: 12px; font-size: 12px; display: inline-block; margin: 2px; }
.vlan-tags { display: flex; flex-wrap: wrap; gap: 4px; margin-top: 8px; }
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</style>
<div class="calc-container">
<div class="calc-header">
<h2>VLAN &amp; 802.1Q Trunking Analyzer</h2>
<p>Analysera VLAN-tillåtna listor, beräkna taggoverhead och planera QinQ MTU-påverkan.</p>
</div>
Avsnitt 1: VLAN Allowed List Parser
<div class="result-section">
<div class="section-header">VLAN Tillåten List Parser</div>
<div class="section-content">
<div class="input-grid">
<div class="input-group" style="grid-column:1/-1">
<label>VLAN-lista (t.ex. 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()">Analysera</button>
</div>
<div id="vlanResult" style="display:none;margin-top:15px"></div>
</div>
</div>
Avsnitt 2: 802.1Q Tag Overhead Calculator
<div class="result-section">
<div class="section-header">802.1Q Tag Overhead Calculator</div>
<div class="section-content">
<div class="input-grid">
<div class="input-group">
<label>Bas MTU (byte)</label>
<input id="baseMtu" max="9216" min="64" type="number" value="1500"/>
</div>
<div class="input-group">
<label>Taggningsläge</label>
<select id="tagMode">
<option value="untagged">Otaggad (ingen overhead)</option>
<option selected="" value="dot1q">802.1Q (enkel tagg, +4 byte)</option>
<option value="qinq">QinQ / 802.1ad (dubbel tagg, +8 byte)</option>
</select>
</div>
<div class="input-group">
<label>Länkhastighet (Gbps)</label>
<select id="linkSpeed">
<option value="1">1 Gbps</option>
<option selected="" value="10">10 Gbps</option>
<option value="25">25 Gbps</option>
<option value="40">40 Gbps</option>
<option value="100">100 Gbps</option>
<option value="400">400 Gbps</option>
</select>
</div>
</div>
<div class="button-container" style="justify-content:flex-start;margin-top:12px">
<button class="calc-button" onclick="calcOverhead()">Kalkylera</button>
</div>
<div id="overheadResult" style="display:none;margin-top:15px"></div>
</div>
</div>
Avsnitt 3: QinQ / 802.1ad Tag Byte Layout Referens
<div class="result-section">
<div class="section-header">QinQ / 802.1ad Double-Tag Planering</div>
<div class="section-content">
<table>
<tr><th>Ramtyp</th><th>Taggbyte</th><th>EtherType</th><th>Fält tillagda</th></tr>
<tr><td>Omärkt 802.3</td><td>0</td><td>—</td><td>—</td></tr>
<tr><td>802.1Q (punkt1q)</td><td>+4</td><td>0x8100</td><td>TPID (2) + TCI: PCP(3) + DEI(1) + VID(12)</td></tr>
<tr><td>QinQ / 802.1ad</td><td>+8</td><td>0x88A8 yttre</td><td>Yttre etikett (4) + inre 802.1Q-etikett (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>