Ethernet应用层有效网速计算方法

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最新推荐文章于 2024-11-15 22:03:16 发布

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分类专栏： Network Snippets 文章标签：网速 ethernet

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此方法用于计算以太网应用层的理论传输速率，理论传输速率跟以下因素相关
第四层：TCP 或 UDP
第三层：IPv4 或 IPv6
第二层：MTU值
第一层：链路速度（10Mbps ~ 100Gbps）

/**
 * calc transfer speed over TCP or UDP
 * @param {number} bps - 10Mbps to 100Gbps
 * @param {mtu} mtu - 1500(standard), 7935(lan) or 9000(jumbo)
 * @param {number} layer3protocol - IPv4 or IPv6
 * @param {number} layer4protocol - TCP or UDP
 * @return {number} - bytes per sec
 * @example calcEffectiveSpeed(1e9, 1500, 'IPv4', 'TCP')
 * @example calcEffectiveSpeed(1e9, 9000, 'IPv4', 'UDP')
 * @see https://en.wikipedia.org/wiki/Frame_check_sequence#/media/File:Ethernet_Frame.png
 * @see https://en.wikipedia.org/wiki/Jumbo_frame#Bandwidth_efficiency
 * @see https://en.wikipedia.org/wiki/Interpacket_gap
 */
function calcEffectiveSpeed(bps, mtu=1500, layer3protocol='IPv4', layer4protocol='TCP'){
  const PREAMABLE=8;
  const IPG=(s)=>s<=10e6?5.875:s<=100e6?12:s<=1e9?8:s<=25e9?5:1;
  const FRAME_HEADER=14;
  const FCS=4;
  const IPV4_HEADER=20;
  const IPV6_HEADER=40;
  const TCP_HEADER=20;
  const UDP_HEADER=8;

  let layer1overhead=PREAMABLE+IPG(bps);
  let layer2overhead=FRAME_HEADER+FCS;
  let layer3overhead=layer3protocol==='IPv4'?IPV4_HEADER:IPV6_HEADER;
  let layer4overhead=layer4protocol==='TCP'?TCP_HEADER:UDP_HEADER;

  let bytesPerSec=bps/8;
  let frameCount=bytesPerSec/(mtu+layer1overhead+layer2overhead);
  let efficiency=(mtu-layer3overhead-layer4overhead)*frameCount/bytesPerSec;
  let effectiveBytesPerSec=bytesPerSec*efficiency;

  return effectiveBytesPerSec;
}