比特派钱包官方|bandwidth

带宽_百度百科

度百科 网页新闻贴吧知道网盘图片视频地图文库资讯采购百科百度首页登录注册进入词条全站搜索帮助首页秒懂百科特色百科知识专题加入百科百科团队权威合作下载百科APP个人中心带宽[dài kuān]播报讨论上传视频信息领域名词收藏查看我的收藏0有用+10本词条由《中国科技信息》杂志社 参与编辑并审核，经科普中国·科学百科认证 。带宽应用的领域非常多，可以用来标识信号传输的数据传输能力、标识单位时间内通过链路的数据量、标识显示器的显示能力。1. 在模拟信号系统又叫频宽，是指在固定的时间可传输的资料数量，亦即在传输管道中可以传递数据的能力。通常以每秒传送周期或赫兹(Hz)来表示。2. 在数字设备中，带宽指单位时间能通过链路的数据量。通常以bps来表示，即每秒可传输之位数。中文名带宽外文名Band Width别    名频带宽度、频宽单    位bps或Hz领    域信息目录1意义▪应用▪显卡中的带宽▪总线中的带宽▪内存中的带宽▪带宽匹配的问题2在数字信号系统中的意义3在模拟信号系统中的意义4带宽在人力资源领域中的意义5带宽在显示器系统中的意义意义播报编辑带宽一词最初指的是电磁波频带的宽度，也就是信号的最高频率与最低频率的差值。它被更广泛地借用在数字通信中，用来描述网络或线路理论上传输数据的最高速率。这并不是它的学术定义，而是被引申地使用了 [1]。总线带宽指的是总线在单位时间内可以传输的数据总量，等于总线位宽与工作频率的乘积。例如：对于64位、800MHz的前端总线，它的数据传输率就等于64bit×800×1000×1000Hz÷8(Byte)÷1024÷1024÷1024≈6.0GB/s内存带宽指的是内存总线所能提供的数据传输能力。例如：DDR400内存的数据传输频率为200MHz，那么单条模组就拥有64bit×200×2（ddr是上下沿采集信号）×1000×1000Hz÷8(Byte)÷1024÷1024÷1024≈6.0GB/s的带宽。应用一、表示频带宽度信号的带宽是指该信号所包含的各种不同频率成分所占据的频率范围。频宽对基本输出入系统 (BIOS ) 设备尤其重要，如快速磁盘驱动器会受低频宽的总线所阻碍。二、表示通信线路所能传送数据的能力带宽在单位时间内从网络中的某一点到另一点所能通过的“最高数据率”。对于带宽的概念，比较形象的一个比喻是高速公路。单位时间内能够在线路上传送的数据量，常用的单位是bps(bit per second)。计算机网络的带宽是指网络可通过的最高数据率，即每秒多少比特。严格来说，数字网络的带宽应使用波特率来表示（baud），表示每秒的脉冲数。而比特是信息单位，由于数字设备使用二进制，则每位电平所承载的信息量是以2为底2的对数，如果是四进制，则是以2为底4的对数，每位电平所承载的信息量为2。因此，在数值上，波特与比特是相同的。由于人们对这两个概念分的并不是很清楚，因此常使用比特率来表示速率，也正是用比特的人太多，所以比特率也就成了一个带宽事实的标准叫法了。bit/s=1Kbit/sbit/s=1Mbit/sbit/s=1Gbit/s描述带宽时常常把“比特/秒”省略。例如，带宽是1M，实际上是1Mbps，这里的Mbps是指兆位/s。在网络中有两种不同的速率：1、信号（即电磁波）在传输媒体上的传播速率（米/秒，或公里/秒）。2、计算机向网络发送比特的速率（比特/秒）。这两种速率的意义和单位完全不同。在理解带宽这个概念之前，首先来看一个公式：带宽=时钟频率x总线位数/8（单位B/s），从公式中可以看到，带宽和时钟频率、总线位数是有着非常密切的关系的。其实在一个计算机系统中，不仅显示器、内存有带宽的概念，在一块板卡上，带宽的概念就更多了，完全可以说是带宽无处不在。为了更形象地理解带宽、位宽、时钟频率的关系，举个比较形象的例子，工人加工零件，如果一个人干，在大家单个加工速度相同的情况下，肯定不如两个人干的多，带宽就像是工人能够加工零件的总数量，位宽仿佛工人数量，时钟工作频率相当于加工单个零件的速度，位宽越宽，时钟频率越高则总线带宽越大,其好处也是显而易见的。带宽主板上通常会有两块比较大的芯片，一般将靠近CPU的那块称为北桥，远离CPU的称为南桥。北桥的作用是在CPU与内存、显卡之间建立通信接口，它们与北桥连接的带宽大小很大程度上决定着内存与显卡效能的大小。南桥是负责计算机的I/O设备、PCI设备和硬盘，对带宽的要求，相比较北桥而言，是要小一些的。而南北桥之间的连接带宽一般就称为南北桥带宽。随着计算机越来越向多媒体方向发展，南桥的功能也日益强大，对于南北桥间的连接总线带宽也是提出了新的要求，在INTEL的9X5系列主板上，南北桥的带宽将从以前一直为人所诟病的266MB/S发展到空前的2GB/S，一举解决了南北桥间的带宽瓶颈。显卡中的带宽带宽玩游戏的朋友都知道，当玩一些大制作游戏的时候，画面有时候会卡的比较厉害。其实这就是显卡带宽不足的问题，再具体点说，这是显存带宽不足。众所周知，当道的AGP接口是AGP 8X，而AGP总线的频率是PCI总线的两倍，也就是266MHz,很容易就可以换算出它的带宽是2.1Gbps，这样的带宽就显得很微不足道了，因为连最普通的ATI R9000的显存带宽都要达到400MHz*128Bit/8=6.4GB/s,其余的高端显卡更是不用说了。正因为如此，INTEL在最新的9X5芯片组中，采用了PCI-Express总线来替代老态龙钟的AGP总线，与传统PCI以及更早期的计算机总线的共享并行架构相比，PCI Express最大的特点是在设备间采用点对点串行连接,如此一来即允许每个设备都有自己的专用连接，不需要向整个总线请求带宽，同时利用串行的连接特点将能轻松将数据传输速度提到一个很高的频率。在传输速度上，由于PCI Express支持双向传输模式，因此连接的每个装置都可以使用最大带宽。AGP所遇到的带宽瓶颈也迎刃而解。总线中的带宽在计算机系统中，总线的作用就好比是人体中的神经系统，它承担的是所有数据传输的职责，而各个子系统间都必须籍由总线才能通讯，例如，CPU和北桥间有前端总线、北桥与显卡间为AGP总线、芯片组间有南北桥总线，各类扩展设备通过PCI、PCI-X总线与系统连接；主机与外部设备的连接也是通过总线进行，流行的USB2.0、IEEE1394总线等等，一句话，在一部计算机系统内，所有数据交换的需求都必须通过总线来实现。按照工作模式不同，总线可分为两种类型，一种是并行总线，它在同一时刻可以传输多位数据，好比是一条允许多辆车并排开的宽敞道路，而且它还有双向单向之分；另一种为串行总线，它在同一时刻只能传输一个数据，好比只容许一辆车行走的狭窄道路，数据必须一个接一个传输、看起来仿佛一个长长的数据串，故称为“串行”。带宽对串行总线来说，带宽和工作频率的概念与并行总线完全相同，只是它改变了传统意义上的总线位宽的概念。在频率相同的情况下，并行总线比串行总线快得多，但它存在并行传输信号间的干扰现象，频率越高、位宽越大，干扰就越严重，因此要大幅提高现有并行总线的带宽是非常困难的；而串行总线不存在这个问题，总线频率可以大幅向上提升，这样串行总线就可以凭借高频率的优势获得高带宽。而为了弥补一次只能传送一位数据的不足，串行总线常常采用多条管线（或通道）的做法实现更高的速度——管线之间各自独立，多条管线组成一条总线系统，从表面看来它和并行总线很类似，但在内部它是以串行原理运作的。对这类总线，带宽的计算公式就等于“总线频率×管线数”，这方面的例子有PCIExpress和HyperTransport，前者有×1、×2、×4、×8、×16和×32多个版本，在第一代PCIExpress技术当中，单通道的单向信号频率可达2.5GHz，以×16举例，这里的16就代表16对双向总线，一共64条线路，每4条线路组成一个通道，二条接收，二条发送。这样可以换算出其总线的带宽为2.5GHz×16/10=4GB/s（单向）。除10是因为每字节采用10位编码。并行总线和串行总线的描述参数存在一定差别。对并行总线来说，描述的性能参数有以下三个：总线宽度、时钟频率、数据传输频率。其中，总线宽度就是该总线可同时传输数据的位数，好比是车道容许并排行走的车辆的数量；例如，16位总线在同一时刻传输的数据为16位，也就是2个字节；而32位总线可同时传输4个字节，64位总线可以同时传输8个字节......显然，总线的宽度越大，它在同一时刻就能够传输更多的数据。不过总线的位宽无法无限制增加。总线的带宽指的是这条总线在单位时间内可以传输的数据总量，它等于总线位宽与工作频率的乘积。例如，对于64位、800MHz的前端总线，它的数据传输率就等于64bit×800MHz÷8(Byte)=6.4GB/s；32位、33MHzPCI总线的数据传输率就是32bit×33MHz÷8=133MB/s，等等，这项法则可以用于所有并行总线上面——看到这里，读者应该明白我们所说的总线带宽指的就是它的数据传输率，其实“总线带宽”的概念同“电路带宽”的原始概念已经风马牛不相及。内存中的带宽带宽除总线之外，内存也存在类似的带宽概念。其实所谓的内存带宽，指的也就是内存总线所能提供的数据传输能力，但它决定于内存芯片和内存模组而非纯粹的总线设计，加上地位重要，往往作为单独的对象讨论。SDRAM、DDR和DDRⅡ的总线位宽为64位，RDRAM的位宽为16位。而这两者在结构上有很大区别：SDRAM、DDR和DDRⅡ的64位总线必须由多枚芯片共同实现，计算方法如下：内存模组位宽=内存芯片位宽×单面芯片数量（假定为单面单物理BANK）；如果内存芯片的位宽为8位，那么模组中必须、也只能有8颗芯片，多一枚、少一枚都是不允许的；如果芯片的位宽为4位，模组就必须有16颗芯片才行，显然，为实现更高的模组容量，采用低位宽的芯片是一个好办法。而对RDRAM来说就不是如此，它的内存总线为串联架构，总线位宽就等于内存芯片的位宽。和并行总线一样，内存的带宽等于位宽与数据传输频率的乘积，例如，DDR400内存的数据传输频率为400MHz，那么单条模组就拥有64bit×400MHz÷8(Byte)=3.2GB/s的带宽；PC800标准RDRAM的频率达到800MHz，单条模组带宽为16bit×800MHz÷8=1.6GB/s。为了实现更高的带宽，在内存控制器中使用双通道技术是一个理想的办法，所谓双通道就是让两组内存并行运作，内存的总位宽提高一倍，带宽也随之提高了一倍。带宽可以说是内存性能最主要的标志，业界也以内存带宽作为主要的分类标准，但它并非决定性能的唯一要素，在实际应用，内存延迟的影响并不亚于带宽。如果延迟时间太长的话相当不利，此时即便带宽再高也无济于事。带宽匹配的问题计算机系统中存在形形色色的总线，这不可避免带来总线速度匹配问题，其中最常出问题的地方在于前端总线和内存、南北桥总线和PCI总线。前端总线与内存匹配与否对整套系统影响最大，最理想的情况是前端总线带宽与内存带宽相等，而且内存延迟要尽可能低。在Pentium4刚推出的时候，Intel采用RDRAM内存以达到同前端总线匹配，但RDRAM成本昂贵，严重影响推广工作，Intel曾推出搭配PC133SDRAM的845芯片组，但SDRAM仅能提供1.06GB/s的带宽，仅相当于400MHz前端总线带宽的1/3，严重不匹配导致系统性能大幅度下降；后来，Intel推出支持DDR266的845D才勉强好转，但仍未实现与前端总线匹配；接着，Intel将P4前端总线提升到533MHz、带宽增长至5.4GB/s，虽然配套芯片组可支持DDR333内存，可也仅能满足1/2而已；P4的前端总线提升到800MHz，而配套的865/875P芯片组可支持双通道DDR400——这个时候才实现匹配的理想状态，当然，这个时候继续提高内存带宽意义就不是特别大，因为它超出了前端总线的接收能力。南北桥总线带宽曾是一个尖锐的问题，早期的芯片组都是通过PCI总线来连接南北桥，而它所能提供的带宽仅仅只有133MB/s，若南桥连接两个ATA-100硬盘、100M网络、IEEE1394接口......区区133MB/s带宽势必形成严重的瓶颈，为此，各芯片组厂商都发展出不同的南北桥总线方案，如Intel的Hub-Link、VIA的V-Link、SiS的MuTIOL，还有AMD的HyperTransport等等，它们的带宽都大大超过了133MB/s，最高纪录已超过1GB/s，瓶颈效应已不复存在。PCI总线带宽不足还是比较大的矛盾，PC上使用的PCI总线均为32位、33MHz类型，带宽133MB/s，而这区区133MB/s必须满足网络、硬盘控制卡（如果有的话）之类的扩展需要，一旦使用千兆网络，瓶颈马上出现，业界打算自2004年开始以PCIExpress总线来全面取代PCI总线，届时PCI带宽不足的问题将成为历史。在数字信号系统中的意义播报编辑数字信号系统中，带宽用来标识通讯线路所能传送数据的能力，即在单位时间内通过网络中某一点的最高数据率，常用的单位为bps（又称为比特率---bit per second，每秒多少比特）。在日常生活中中描述带宽时常常把bps省略掉，例如：带宽为4M，完整的称谓应为4Mbps。针对于带宽成本降低，用户接入速率也是越来越高，从最初的拨号上网，到20M甚至100M光纤。但是随着计算机的发展，用户对‘带宽’的认识也应该有更大的提高。一般来说，带宽是以 bit（比特）表示，而电信，联通，移动等运营商在推广的时候往往忽略了这个单位。正常换算情况如下：1Mbit=128KB2Mbit=256KB（以此类推）而换算后的速度才是真实上网的速度，也就是说，如果从运营商开通的带宽是10M，那么代入计算公式，以上面换算的1M来计量。则为：（1M=1024K）1M/128K=1024/128=810/8=1.25M也就是说如果开通10M带宽，可以达到最高1.25M的速度。一般来说，一台计算机观看电影，玩游戏等，4M带宽足够。但是如果需要经常下载大文件，建议还是使用更高带宽。在模拟信号系统中的意义播报编辑在模拟信号系统中，带宽用来标识传输信号所占有的频率宽度，这个宽度由传输信号的最高频率和最低频率决定，两者之差就是带宽值，因此又被称为信号带宽或者载频带宽，单位为Hz。带宽其实就是信号所占用的频谱的度量，可以看做是一种与空间相关的量。与之相比，信号的传输速率就是一种与空间和时间都相关的物理量，定义为单位时间内在信道上传输的数据量。为了合理使用频谱资源，国际电信联盟（ITU）为每种通信系统都规定了频率范围，这种频率范围又称为频段，而频段的频谱宽度又被称之为工作带宽。例如GSM的工作带宽为25 MHz，WCDMA和CDMA均为30 MHz。带宽在人力资源领域中的意义播报编辑所谓“带宽”就是指各等级薪资的最大值与最小值之差，又将其成为薪值的分布区间。一般而言，由于职位高低不同，职位或职层所涉及技能与职责的复杂性程度也会有所不同，因此，各职等级的薪资带宽也就应该有所不同（薪资带宽应当能反应一个职位或职层的任职者由一个初入者到能力与业绩十分突出者所需要的难度大小）。如果职位或职层所涉及的技能与职责能在较短时间内得以掌握，则此等级薪资的带宽较窄；而如果职位或职层所涉及的技能和职责需要学习的时间较长，继续提升的机会也较小，则其相应的带宽较大。根据这个理论，变革者在设计职等带宽时应当坚持的原则是：职等越高，其带宽就应越大，因为职等越高，任职者胜任的速度就越慢。带宽在显示器系统中的意义播报编辑在采用正弦输入研究传感器频率动态特性时，常用频率特性和相频特性来描述传感器的动态特性，其重要指标是频带宽度，简称带宽。带宽（Bandwidth）是显示器视频放大器通频宽度的简称，指的是电子枪在一秒钟内扫描过像素（Pixel）的总个数，即单位时间内所有行（水平方向）扫描线和场（竖直方向）扫描线上显示出的像素个数之总和，单位是MHz。带宽的详细计算公式： B=r(x) ×r(y) ×VB表示显示器的带宽r(x)表示每条水平扫描线上的图素个数r(y)表示每帧画面的水平扫描线数V 表示每秒画面刷新率带宽其实就是单位时间内传输的数据的多少。新手上路成长任务编辑入门编辑规则本人编辑我有疑问内容质疑在线客服官方贴吧意见反馈投诉建议举报不良信息未通过词条申诉投诉侵权信息封禁查询与解封©2024 Baidu 使用百度前必读 | 百科协议 | 隐私政策 | 百度百科合作平台 | 京ICP证030173号 京公网安备110000020000

如何理解计算机网络性能指标之速率与带宽的区别？ - 知乎

如何理解计算机网络性能指标之速率与带宽的区别？ - 知乎首页知乎知学堂发现等你来答​切换模式登录/注册计算机计算机网络网络带宽如何理解计算机网络性能指标之速率与带宽的区别？我先讲一下自己的理解 --- 速率，指的是连接在计算机网络上的主机在数字信道上传送数据的速率，它也称为数据率或比特率，单位是bps。速率往往指的是额定…显示全部 ​关注者93被浏览129,434关注问题​写回答​邀请回答​好问题 8​添加评论​分享​18 个回答默认排序寒深codegetter.io作者｜ByteDance SDE​ 关注这个回答认为题主的速率与带宽分别对标英文中的speed和network。speed更多的是涉及物理概念，描述的是一个网络线路中硬件所能承载的最大的bit/s值。举个例子，一段网络电缆，根据其物理特性，speed最多也就是10Gbps。你可以这样想象，你站在一个管子的出口，在你面前不断地有一种叫做bit的生物跑出来，一会儿是0一会儿是1，它们“奔跑的速度”就是我们讲的speed。不同硬件技术可能会有不同的speed，比如无线网络的speed就会比电缆的speed小一点（可能吧，反正不同就是了）。bandwidth更多涉及逻辑概念，描述的是你在一秒里面能接收到多少bit的数据。这里可能有人会觉得这跟speed好像听不出来什么区别，别急，我们还是举上面那个bit生物的例子。现在，你观察的不是一根管子，而是两个管子，这两个管子里面都不断的有bit生物跑出来。我们可以确信的是，它们“奔跑的速度”是不变的，因为生物还是那个生物，即speed不变。但是在一秒时间内，你看到的生物却多了一倍，因为现在是两根管子啊！bandwidth就是用来描述这个物理量。由此我们也能知道，bandwidth和speed的度量单位是一样的，都是比特每秒。那么，有没有可能bandwidth会小于speed呢？这是有可能的。我们再举上面比特生物的例子。现在，有两种比特生物，一种是在黑漆漆的管子里开手电筒照明，让其余比特知道路怎么走，另一种是身上背着信息，从管子里跑出来之后把信息告诉你。由于管子太长，比特们决定每4个背着信息的比特前面都必须另外有一个比特专门负责照明。这样，从管子里每出来5个比特，实际上只有4个对你而言是有用的。此时，这条线路的bandwidth = speed * (4/5)。总结一下，就是bandwidth实际上是对于你而言这条线路里面有用的bit的传输速率。此外，通过上面的讲述，你还会发现，假如你要从网络中接收一个很小的文件，小到只有一个bit，那么，此时对于你而言，bandwidth实际是没有多大意义的，你的接收快慢几乎仅取决于speed。但是，如果你想接收一个很大很大的文件，那么，bandwidth对于你完成接收的快慢就有至关重要的作用。最后一点， 如上所述，因为speed是物理概念，讨论的是一段网络线路的物理极限，所以在现代所有网络技术的讨论中， speed通常是一个硬性条件，没有多少回旋的余地，很少有人会在这上面做文章，所以讨论speed的情况很少。更多时候，大家都是关心bandwidth。编辑于 2017-03-12 14:23​赞同 105​​12 条评论​分享​收藏​喜欢收起​知乎用户你的理解感觉也没啥大问题。我们常常说的传输速率，或者说网速，本质上就是指数据的大小与从主机a完全传递到主机b上所消耗的时间的比值。你把网线想象成水管，两个主机之间的通信想象成一头送水一头出水。我们知道，网线中数据的传输实际上就是电信号的传输，速率接近于光速，因此这个传输速率是恒定的且一般可以忽略不计的，与网速不是一个概念。因此我们假定管道内水的流速也是快到忽略不计的。因此，你发送水的快慢取决于水管的容量，这就是带宽。带宽的单位为bps，表示管道每秒可接收新水的量。比如说，要发送100mbit的数据，带宽为10mbit/s，那么发送完毕所需的时间应为10s，网速则为100mbit/10s=10mbit/s。因此粗略来讲这个网速实际上与带宽是一回事。专业术语中一般都是使用带宽而不是速率来描述链路的性能，因为这个速率就是由带宽所决定的，且这词有歧义。编辑于 2017-01-03 16:48​赞同 6​​1 条评论​分享​收藏​喜欢

BANDWIDTH中文(简体)翻译：剑桥词典

BANDWIDTH中文(简体)翻译：剑桥词典

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bandwidth 在英语-中文（简体）词典中的翻译

bandwidthnoun [ C usually singular or U ] uk

Your browser doesn't support HTML5 audio

/ˈbænd.wɪtθ/ us

Your browser doesn't support HTML5 audio

/ˈbænd.wɪtθ/

bandwidth noun [C usually singular or U]

(INFORMATION)

Add to word list

Add to word list

a measurement of the amount of information that can be sent between computers, through a phone line, etc.

带宽

The system will handle signals that need high bandwidth, for instance those that encode TV pictures.

这个系统可以处理需要高带宽的信号，比如编码压缩过的电视图像信号。

high-bandwidth services/applications

高带宽服务／应用

the ability or time to deal with a situation, especially one that involves a large amount of information or a number of problems

处理大信息或复杂情况所需的时间、精力和综合能力

I don't have the bandwidth to read stuff I know isn't going to lead to productive discussion.

我没有精力去看那种没什么正面意义的东西。

If people misreport or misrepresent my arguments, I am using more of my bandwidth to correct the misreporting.

如果我的论点被误传或歪曲了，那我会花多一点精力去加以纠正。

更多范例减少例句Tasks like simultaneously streaming several different video signals over a wireless connection require more bandwidth.Once software begins to use the extra bandwidth, you'll likely be glad you have it. There's enough bandwidth to let you surf, stream and down- load all at the same time.

bandwidth noun [C usually singular or U]

(RADIO)

the range of frequencies used to send information over a distance using phone wires

频带

in radio, the width of a particular waveband

波段宽度

(bandwidth在剑桥英语-中文（简体）词典的翻译 © Cambridge University Press)

bandwidth的例句

bandwidth

The effect of the additional dispersion introduced by this etalon can be neglected in this instance because the pulse bandwidth is relatively small.

来自 Cambridge English Corpus

The per turbation in the frequency domain can be said to be "localized" inside this bandwidth.

来自 Cambridge English Corpus

Was he referring to the auction of digital bandwidths?

来自 Hansard archive

该例句来自Hansard存档。包含以下议会许可信息开放议会许可v3.0

To achieve greater bandwidths multiple /4 coupling sections are used.

来自 Wikipedia

该例句来自维基百科，在CC BY-SA许可下可重复使用。

Using the band-limited representations with increasing bandwidth, we compute a sequence of band-limited configurations with maximal agility.

来自 Cambridge English Corpus

To get out of this dead end, one would like to use, instead, a spatially varying bandwidth.

来自 Cambridge English Corpus

Therefore, the bandwidth of such virtual viscous damper is lower than that of a real viscous damper.

来自 Cambridge English Corpus

However, since the new model is still constructed by summing disparity-sensitive energy models, the bandwidth for disparity gradient does not improve.

来自 Cambridge English Corpus

示例中的观点不代表剑桥词典编辑、剑桥大学出版社和其许可证颁发者的观点。

B1

bandwidth的翻译

中文（繁体）

頻寬, 處理大量資訊或復雜情況所需的時間、精力和綜合能力, 頻帶…

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西班牙语

ancho de banda digital, ancho de banda…

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largura da banda, largura de barramento, largura de banda…

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przepustowość, szerokośćpasma…

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dalga genişliği, bant aralığı…

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bandsman

bandstand

bandura

bandwagon

bandwidth

bandy

bandy something around

bandy words idiom

bane

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veggie burger

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/ˈvedʒ.i ˌbɜː.ɡər/

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/ˈvedʒ.i ˌbɝː.ɡɚ/

a type of food similar to a hamburger but made without meat, by pressing together small pieces of vegetables, seeds, etc. into a flat, round shape

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Noun 

bandwidth (INFORMATION)

bandwidth (RADIO)

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Throughput, Bandwidth, Latency - 知乎

Throughput, Bandwidth, Latency - 知乎首发于分布式思考切换模式写文章登录/注册Throughput, Bandwidth, LatencyTonyDistributed Small Datum in Sky一、 什么是时延LatencyLatency是一个动作所花费的时间，我们做一个操作，比如：copy一个1G大小的文件，花了10秒，我们说Latency=10秒Latency要注意的几点：1-1、 不同角度Latency不同比如，我们一个Redis Client客户端，给Redis服务器发送了一个Ping命令，我们发送时开始计算时间，等Redis返回一个Pong回应，我们按下秒表，看当前的时间。这两个时间的差值，就是这个动作的时延Latency。如果是局域网内（通用网络，一般是千兆网或万兆网，注意：它是以bit为单位的），一般是200微妙（us）左右，于是，站在Redis Client角度，这个Latency等于200us。但是，站在Redis服务器角度，它从开始看到这个Ping数据包，开始计时，然后写一个Pong字符串到操作系统的网络层（实际就是内存buffer），就算完成了(应该掐表了)。所以，Server角度，它的时间只消耗在内存操作。这个时间有多少，没有人测试过。但我有一个经验数据，请参考下文单线程就比多线程性能差吗？不一定假设最慢的可能，是Server从主存Main Memoory，读一个数据，然后再向主存Main Memory写一个数据，总计就是200ns。但实际上，会比这少很多，因为读写时，数据很可能已经在CPU cache中，如果是L1 Cache，那么只要不到2ns。但不管如何计算，上面的时间，都远小于客户端Redis Client所看到的200us，即至少有一千倍，甚至十万倍的差距。那么时间花在哪里去了？这个客户端和服务器之间的时间差异，被消耗在网络上了。就是数据包通过操作系统的TCP/IP系统栈，走网卡，再经过网络介质（比如铜缆或光缆、Hub或Switch），到达客户端的TCP/IP栈，最后达到客户端的应用层，而且是一来一回，即Round Trip。所以，记住：时延是站在某个掐表计时的实体的角度，不同角度（或不同实体），得到的时间不同，即使是对于同一个动作另外，站在Redis Client角度，它的时延Latency至少有两部分组成，一个是网络上消耗的时间，一个是Server实际内存操作的时间，但由上面的分析可以看出，大头是网络上的部分，所以，我们为简化分析，对于客户端程序的角度而言，经常将占主要时间的部分，当做整个动作的时延。即对于上面这个例子：Redis Client的Ping命令处理的Latency = 网络Round Trip时延1-2、 时延不是定值，而是随机值，我们需要用概率来描述它如果每次包消耗都是一模一样的200us，那就是好事。但如果你多测试几次，你会发现时延是不确定的，有时快，有时慢。这是因为，在实际工作环境里，有很多因素影响这个时延。以上面这个为例，因为通信需要通过网络设备，比如一个Switch，但Switch不可能只为你这一个通信服务，它还需要服务其他客户，因此，有时，Switch就会忙些（甚至有时会打个小盹，比如计时器的影响），让时间或多或少有点变化。但对于一个稳定的系统，一般而言，计算时间发送变化，但如果测试次数足够多，从统计角度看，它是一个比较稳定的值。于是，我们用概率去描述这个统计稳定值，一般用P99, P50， Avarage这些指标来描述。P99就是99%的时间，低于当前这个值。Average，就是所有的次数的时间总和除于次数。这样，我们才能用一个稳定的值作为标识，来替代并不稳定的单次Latency计时。二、 吞吐能力：Throughput2-1、 Throughput和Latency的关系什么是Throughput？Throughput，是我们做很多动作，同时，我们计算一段时间（比如：1秒）里完成的动作数。以上面为例，我们发送一个Ping，返回一个Pong，作为一个动作。然后我们不停发送（但必须等到Pong回来后，才发下一个），然后我们计算1秒内，我们能够处理这样的动作有多少个。数学好的同学，很快能算出，假设Average Latency = 200us，且很稳定的话，那么Throughput = 1秒/200us = 5000 op/秒。即Throughput是5K。同样地，你会发现，Throughput也受上面的两个因素影响。首先，这个Throughput是有角度的，这里的5K，是对于Redis Client客户端而言。而对于服务器，如果它能全速处理，假设每次都从L1 Cache操作数据，它的Throughput是 1秒/2ns，即0.5G(5亿次)。为什么服务器实际没有做到5亿的Throughput，是因为Redis Client发送的太慢，所以对于服务器而言，它大部分时间都在睡觉，只用自己能力的很小一部分来处理Ping命令。同时，Throughtput也需要用统计概率来描述，幸运的是，我们用一段很长的时间，比如秒，来描述Throughput，所以，从统计角度，它一般是个稳定值。（记住：在计算机世界里，1秒是个相当长的时间）那么，Throughput是否能简单地由Latency得来？不可以。因为存在并发。我们假设有2个Redis Client同时向Server发送，我们会发现，它们的Latency不变。站在两个Redis Client一起的角度，我们认为Throughput增加了一倍，即10K。但如果看Latency，并没有变化，还是200us。为什么？因为服务器和网络设备，都能力足够强大，来一个请求，和两个请求一起到，它处理的时间都足够快，所以，并发并不降低服务器端的能力（因为服务器1秒可以处理5亿个Ping请求，两个并发的Redis Client合在一起，每秒也只能送上总和10K的请求），但包在网络上传递的时间（实际是服务器网络层和网络设备的故意等待时间），基本上就是200us。所以，我们可以得到下面两个结论：1. 对于并发，我们不能通过Latency简单换算成Throughput2. 如果只有单客户单顺序执行（即得到第一个结果，才能发送第二个，否则就是并发），而且服务器处理的时间成本忽略不计，那么可以用Latecny换算成Throughput，而且是占在客户端角度那我们能不能用 并发数 * 单个客户端的Throughput，来得到多个客户端的Throughput？也不可以。这是因为，如果并发的客户端形成的数据包，总数还比较小，那么上面的公式是成立的。当并发数足够大，这时，网络的数据量加大，服务器端就不能保证每个包的Round Trip都是200us，而是要更多时间（即单个客户端角度看，Latency加大了）。所以，实际工作中，你需要做真正的测试，用不同的并发数，来测试整个系统的Throughput。有的并发数，是Throughput线性增长，即加大一倍的客户端，整个Throughput也加大一倍。有的并发数，则不能满足这个线性规律。甚至有时增大了并发数，整个Throughput还会降低（比如：某个数值触发了系统里某个部件的瓶颈）2-2、 Throughput还有Pattern的差异如果我们看一个磁盘，它的Throughput应该是每秒读出Read或写入Write的字节数。有一个软件fio，可以很好地测试Throughput。但是，如果你给fio不同的参数，你会惊奇地发现，Throughput差别非常大。我以一个例子来说明，你可以用下面的命令来进行测试。我这里测试的是磁盘Write，为了保证数据数据落盘（即不丢失数据），每次请求完，都要fsync。下面是每写一个block size为4K（--bs=4k），就fsync一次fio --name=w --rw=write --ioengine=sync --direct=0 --fsync=1 --end_fsync=1 --size=200M --bs=4k;在我的Mac机器上，输出是：Throughput = 2.8MB/s然后改为每写一个block size为1024K（--bs=1024k），就fsync一次fio --name=w --rw=write --ioengine=sync --direct=0 --fsync=1 --end_fsync=1 --size=200M --bs=1024k;在我的机器上，这次输出是：Throughput = 191MB/s这里有60多倍的差别。你可以在自己的机器上测试，因为每个机器的SSD磁盘的特性不一样，得到的数字和倍数会偶差别，但都会是一个很大的倍数。也就是说，SSD面对不同的pattern（即不同的block size），表现的Throughput有可能有巨大的差别。2-3、 Throughput有效性的差别还是以磁盘为例，对于SSD磁盘，其最小读/写的单位是4K。即我们即使每次读1K的数据，它也要每次读出至少4K数据。所以，假设我们每次都读1K的内容，即使磁盘能达到Throughput=400MB/s，但我们客户端角度看，实际的有效值只有100MB/s。站在磁盘角度，其Throughput是400MB/s，但站在客户端角度，它只能看到吞吐Thourghput是100MB/s。我们很多存储在磁盘的数据结构，不管是B+树，还是LSM树，都存在读写放大。比如：对于LSM树，我们即使有效地写入了100M/B的Throughput，它后台还需要做compaction，针对这每秒的100M的数据进行多层压缩，这就是附加的读写。我们假设写放大是10倍，那么占在客户端角度，如果我们想达到100MB/s的Throughput，我们就需要磁盘至少能支持1GB/s的Throughput。三、 带宽：Bandwidth哪什么是Bandwidth？Bandwidth，就是站在某个硬件（或部件，但一般不会是客户端角度），在某个Pattern下，同时有效性为100%的情况下，能达到的最大的Throughput。所以，当你搭建系统时，购买或选择硬件时，会读到其产品说明书，最开始的广告数字，都是Bandwidth。但实际工作中，你要注意：这个Bandwidth，并不是你可以简单推算你的应用程序的Throughput，你需要清楚，你的Pattern是否匹配硬件，你的数据结构和系统架构，是否100%的利用了硬件。我们需要在生产环境中，尽可能利用好硬件，特别是瓶颈硬件的Bandwidth，让自己的Pattern和硬件匹配，同时有效性尽可能高。各个硬件的Bandwidth不同，如上例中，对于内存，其Bandwidth可以到100GB/s左右，对于不同的网卡，其Bandwidth一般是1Gb/s、10Gb/s、25Gb/s、100Gb/s，而对于SSD磁盘，有高有低，我看到有宣传超过1GB/s的SSD盘（但我自己从没有用过）。但一般而言，磁盘是最慢的，上面的几个数字也能推算出。一个系统的Throughput，像一桶水一样，是由最短的那个板决定容量。所以，我们需要特别关注最慢的硬件，也就是磁盘。同时，我们要用好Pattern和有效率，尽量使整个系统（也就是客户端角度）Throughput去靠近这个Bandwidth。四、 参考我自己比较关注磁盘的特性，做了一些实验，详细可参考：https://hub.fastgit.xyz/szstonelee/SSDInternal/blob/master/scenario.md编辑于 2022-09-02 10:23吞吐量带宽测速时延测量​赞同 58​​5 条评论​分享​喜欢​收藏​申请转载​文章被以下专栏收录分布式思考分布式设计的一些个

“带宽”(bandwidth)有以下两种不同的意义 - 知乎

“带宽”(bandwidth)有以下两种不同的意义 - 知乎切换模式写文章登录/注册“带宽”(bandwidth)有以下两种不同的意义娃哈哈女it民工，喜欢摄影，宠物“带宽”(bandwidth)有以下两种不同的意义：(1) 带宽本来是指某个信号具有的频带宽度。信号的带宽是指该信号所包含的各种不同频率成份所占据的频率范围。例如，在传统的通信线路上传送的电话信号的标准带宽是3.1kHz （从300 Hz到3.4kHz，即话音的主要成分的频率范围）。这种意义的带宽的单位是赫（或千赫、兆赫、吉赫等）。在过去很长的一段时间，通信的主干线路传送的是模拟信号（即连续变化的信号）。因此，表示通信线路允许通过的信号频带范围就称为线路的带宽（或通频带）。(2) 在计算机网络中，带宽用来表示网络的通信线路传送数据的能力，因此网络带宽表示在单位时间内从网络中的某一点到另一点所能通过的“最高数据率”。发布于 2020-08-31 14:52​赞同 15​​1 条评论​分享​喜欢​收藏​申请

频带_百度百科

度百科 网页新闻贴吧知道网盘图片视频地图文库资讯采购百科百度首页登录注册进入词条全站搜索帮助首页秒懂百科特色百科知识专题加入百科百科团队权威合作下载百科APP个人中心频带[pín dài]播报讨论上传视频信号所占据的频带宽度收藏查看我的收藏0有用+10本词条由“科普中国”科学百科词条编写与应用工作项目 审核 。频带，即带宽，指信号所占据的频带宽度；在被用来描述信道时，带宽是指能够有效通过该信道的信号的最大频带宽度。对于模拟信号而言，带宽又称为频宽，以赫兹（Hz）为单位。例如模拟电话的信号带宽为3100Hz，一个PAL-D电视频道的带宽为8MHz（含保护带宽）。对于数字信号而言，带宽是指单位时间内链路能够通过的数据量。例如ISDN的B信道带宽为64Kbps。由于数字信号的传输是通过模拟信号的调制完成的，为了与模拟带宽进行区分，数字信道的带宽一般直接用波特率或符号率来描述。带宽在信息论、无线电、通信、信号处理和波谱学等领域都是一个核心概念。中文名频带外文名band width别    名带宽单    位赫兹Hz解    释无线电频谱上频率界限之间的部分领    域信息论、无线电、通信、信号处理和波谱学等目录1解释2模拟系统3数字系统4网页寄存5参见解释播报编辑带宽在许多应用中都是一个关键的概念。例如在无线电通信中，带宽是调制载波占据的频率范围，然而在光学中带宽是单个谱线宽度或者整个频谱范围。对于不同的应用领域有不同的精确定义。例如，其中一个带宽定义就是超出范围的频率函数为零的频率范围。这就对应于数学概念中的函数，例如函数不是零的所有值的“长度”。另外一些定义可能没有那么严格，它们丢弃了频率函数“很小”的信号频率。很小可能是意味着它的值在最大值 3dB以下，也就是最大值的一半以下；也可能是小于某一个绝对值。由于函数的宽度有各种各样的定义，带宽的定义也就多种多样，分别用于不同的系统。根据Shannon-Hartley 定理，可靠通信的数据速率直接与通信所用信号频率范围成比例。在这篇文章中，带宽一词有时用来表示数据速率，有时也表示通信系统的频率范围，有时同时表示两个概念。 [1]模拟系统播报编辑图1.带宽对于在数学上可以看作时间函数的模拟信号来说，带宽是以赫兹为单位、信号的傅里叶变换不为0的频率范围。这个定义也可以不严格地定义为在频域内信号的傅里叶变换功率在一个特定门限之上、例如与最大值差在 3dB 的范围之内的频率范围。信号带宽是信号随着时间波动速度的一个度量，这样，带宽越大，信号的变化越快。上面是信号带宽的描述，带宽也可以用于系统。在表示系统带宽的时候，系统带宽是系统传递函数带宽的简称。例如，函数的 3dB 带宽在图上表示是，但是其它的带宽定义就会得到另外不同的结果。一个常用的数量是分数带宽，它是除以设备中心频率得到的带宽。例如，一个带宽 2MHz、中心频率 10MHz 的设备的分数带宽是 2/10 或者表示为 20%。实数基带系统既有负频率又有正频率这样一种现实可能使带宽变得易于混淆，因为有时带宽仅仅用来表示正的一半，例如我们偶尔可以看到这样的表示B=2W，其中B是总的带宽，W是正的带宽，如果需要为这个信号设计一个低通滤波器，那么截止频率至少要保证W不受影响。电子滤波器带宽是频率响应在峰值中心频率响应差在 3dB 范围内的频率部分。在信号处理和控制理论中，带宽是闭环系统增益衰减到 −3dB 的频率。在基础电路理论中带通和带阻滤波器的带宽表示频域中信号强度是最大信号强度的两个频率之间的距离。在光子学中，带宽有不同的含义：某些光源输出的带宽，例如 ASE 光源或者激光；超短光脉冲的带宽可能非常宽广；例如光纤等一些组件能够传输的频率范围宽度；光学放大器的增益带宽；其它现象的范围（例如，反射、非线性过程的相位匹配、或者谐振）；光学调制器的最大调制频率或者调制频率范围；一些测量仪器（例如功率计）能够工作的频率范围；光学通信系统能够达到的数据速率（例如 Gbit/s）。 [2]数字系统播报编辑在数字通信系统中，带宽有两种含义。从技术意义上来说，它是波特率的俗称，波特率是系统传输数据符号的速度；口语中它也用来表示信道容量，信道容量是系统能够传输数据的速度（参见Shannon Limit）。这样，有32 条独立数据线的66MHz数字总线可以恰当地说成是66MHz 带宽、2.1Gbit/s 的数据传输能力，但是对于总线“带宽2.1Gbit/s”这样一种说法这也不应感到奇怪。对于模拟的调制解调器来说也有同样的问题，对它来说，每个符号携带多位的消息所以通过带宽12kHz 的电话线能够传输56kbit/s 的消息。在离散时间系统和数字信号处理中，根据Nyquist-Shannon 采样定理带宽与采样率有关。带宽也用于日常生活中用表示某些有限的或者花费金钱的东西。这样，通信消耗带宽，不合理地使用其它人的带宽可以称为bandwidth theft。 [2]网页寄存播报编辑一些虚拟主机服务商会给带宽以不同的含义。在这里，带宽几乎变成了一个流量概念。意思是指定时间内的下行数据总量。意味着如果一个网页寄存公司给你2GB每月的带宽，那么意味着你的用户每月只能最多下载2GB的内容。 [2]参见播报编辑香农定律调制波特率-符号率吞吐量带宽 (计算机)新手上路成长任务编辑入门编辑规则本人编辑我有疑问内容质疑在线客服官方贴吧意见反馈投诉建议举报不良信息未通过词条申诉投诉侵权信息封禁查询与解封©2024 Baidu 使用百度前必读 | 百科协议 | 隐私政策 | 百度百科合作平台 | 京ICP证030173号 京公网安备110000020000

What Is Bandwidth? Definition, Meaning, and How Much You Need

What Is Bandwidth? Definition, Meaning, and How Much You Need

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What Is Bandwidth? Definition, Meaning, and How Much You Need

Everything you need to know to tweak your setup for a faster internet connection when you need it

By

Tim Fisher

Tim Fisher

Senior Vice President & Group General Manager, Tech & Sustainability

Emporia State University

Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the SVP and General Manager of Lifewire.

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Updated on October 21, 2023

Reviewed by

Michael Barton Heine Jr

Reviewed by

Michael Barton Heine Jr

Michael Heine is a CompTIA-certified writer, editor, and Network Engineer with 25+ years' experience working in the television, defense, ISP, telecommunications, and education industries.

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Definition of Bandwidth

Why You Need to Understand Bandwidth

How to Measure Bandwidth

Bandwidth Is Like Plumbing

Mbps vs. MBps

Bandwidth Control

Frequently Asked Questions

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This article explains what bandwidth is, how to measure it, and how to determine how much you need.

Definition of Bandwidth

Bandwidth is defined as the amount of information that something, like a connection to the internet, can handle at a given time.

The term bandwidth has a number of technical meanings but, since the popularization of the internet, it generally refers to the volume of information per unit of time that a transmission medium (like an internet connection) can handle.

An internet connection with a larger bandwidth can move a set amount of data (say, a video file) much faster than an internet connection with a lower bandwidth.

Bandwidth is typically expressed in bits per second, like 60 Mbps or 60 Mb/s, to explain a data transfer rate of 60 million bits (megabits) every second.

Why Bandwidth Is Important to Understand

Lifewire / Nusha Ashjaee

It's easy to dismiss bandwidth as a technical term that doesn't really apply to you unless you like to play around with tech products or set up internet hardware. In reality, learning what bandwidth means and how it applies to your own network can help you tweak your setup to get a faster internet connection when you need it.

You might be curious about bandwidth if your internet connection is suddenly slower than it is most days. Maybe you suspect that you should buy more bandwidth or that you're not getting what you're paying for.

Or, maybe you're about to buy a gaming console or video streaming service and need an accurate understanding of whether or not you can do so without it negatively impacting the rest of your network. For most people, those two activities are by far the biggest bandwidth hoggers.

How Much Bandwidth Do You Have? (& How Much Do You Need?)

WOW! Speed Test.

See How to Test Your Internet Speed for help on how to accurately determine how much bandwidth you have available to you. Internet speed test sites are often, but not always, the best way to do that.

How much bandwidth you need depends on what you plan on doing with your internet connection. For the most part, more is better, constrained, of course, by your budget.

In general, if you plan on doing nothing but Facebook and the occasional video watching, a low-end high-speed plan is probably just fine.

Depending on what you're using the internet for, you might be able to get an official bandwidth recommendation so that you know exactly what you'll need to use that service optimally. For example, if your internet runs smoothly right now but you plan to add a movie streaming service to the mix, do some research on their website for the minimum bandwidth they recommend for interruption-free streaming.

If you have a few TVs that will be streaming Netflix, and more than a few computers, tablets, and other devices that might be doing who-knows-what, I'd go with as much as you can afford. You won't be sorry.

Bandwidth Is a Lot Like Plumbing

Plumbing provides a great analogy for bandwidth... seriously!

Data is to available bandwidth as water is to the size of the pipe.

In other words, as the bandwidth increases so does the amount of data that can flow through in a given amount of time, just like as the diameter of the pipe increases, so does the amount of water that can flow through during a period of time.

Say you're streaming a movie, someone else is playing an online multiplayer video game, and a couple others on your same network are downloading files or using their phones to watch online videos. It's likely that everyone will feel that things are a bit sluggish if not constantly starting and stopping. This has to do with bandwidth.

To return to the plumbing analogy, assuming the water pipe to a home (the bandwidth) remains the same size, as the home's faucets and showers are turned on (data downloads to the devices), the water pressure at each point (the perceived "speed" at each device) will reduce—again, because there's only so much water (bandwidth) available to the home (your network).

Put another way: the bandwidth is a fixed amount based on what you pay for. While one person may be able to stream a high-def video without any lag whatsoever, the moment you begin adding other download requests to the network, each one will get just their portion of the full capacity.

For example, if a speed test identifies my download speed as 7.85 Mbps, it means that given no interruptions or other bandwidth-hogging applications, I could download a 7.85 megabit (or 0.98 megabytes) file in one second. A little math would tell you that at this allowed bandwidth, I could download about 60 MB of information in one minute, or 3,528 MB in an hour, which is equivalent to a 3.5 GB file...pretty close to a full-length, DVD-quality movie.

So, while I could theoretically download a 3.5 GB video file in an hour, if someone else on my network tries to download a similar file at the same time, it would now take two hours to complete the download because, again, the network only permits x amount of data to be downloaded at any given time, so it now must allow the other download to use some of that bandwidth, too.

Technically, the network would now see 3.5 GB + 3.5 GB, for 7 GB of total data that needs to be downloaded. The bandwidth capacity doesn't change because that's a level you pay your ISP for, so the same concept applies: a 7.85 Mbps network is going to now take two hours to download the 7 GB file just like it would take just one hour to download half that amount.

The Difference in Mbps and MBps

It's important to understand that bandwidth can be expressed in any unit (bytes, kilobytes, megabytes, gigabits, etc.). Your ISP might use one term, a testing service another, and a video streaming service yet another. You'll need to understand how these terms are all related and how to convert between them if you want to avoid paying for too much internet service or, maybe worse, ordering too little for what you want to do with it.

For example, 15 MBs is not the same as 15 Mbs (note the lowercase b). The first reads as 15 megaBYTES while the second is 15 megaBITS. These two values are different by a factor of 8 since there are 8 bits in a byte.

If these two bandwidth readings were written in megabytes (MB), they'd be 15 MBs and 1.875 MBs (since 15/8 is 1.875). However, when written in megabits (Mb), the first would be 120 Mbs (15x8 is 120) and the second 15 Mbps.

What Is a Megabit (Mb)?

This same concept applies to any data unit you might encounter. You can use an online conversion calculator like But Calculatort if you'd rather not do the math manually. See Terabytes, Gigabytes, & Petabytes: How Big are They? for more information.

Bandwidth Control

Some software lets you limit the amount of bandwidth that the program is allowed to use, which is really helpful if you still want the program to function but it doesn't necessarily need to be running at full speed. This intentional bandwidth limitation is often called bandwidth control.

Some download managers, like Free Download Manager, for example, support bandwidth control, as do numerous online backup services, cloud storage services, torrenting programs, and routers. These are all services and programs that tend to deal with massive amounts of bandwidth, so it makes sense to have options that limit their access.

As an example, say you want to download a really large 10 GB file. Instead of having it download for hours, sucking away all the available bandwidth, you could use a download manager and instruct the program to limit the download to use only 10 percent of the available bandwidth.

This would, of course, drastically add time to the total download time but it would also free up a lot more bandwidth for other time-sensitive activities like live video streams.

Something similar to bandwidth control is bandwidth throttling. This is also a deliberate bandwidth control that's sometimes set by internet service providers to either limit certain types of traffic (like Netflix streaming or file sharing) or to limit all traffic during particular periods of time during the day in order to reduce congestion.

Network performance is determined by more than just how much bandwidth you have available. There are also factors like latency, jitter, and packet loss that could be contributing to less-than-desirable performance in any given network. Some other elements at play that can cause sluggish internet include old hardware, viruses, browser add-ons, and a weak Wi-Fi connection.

FAQ

Can I see what is using bandwidth and how much?

There are several ways to monitor network traffic. For instance, you can use your router or a third-party application. Your ISP website might provide bandwidth monitoring as well.

How much bandwidth does Netflix use per hour?

Netflix offers four data usage settings: Low: up to 0.3 GB per hour; Medium: up to 0.7 GB per hour; High: 1-7 GB per hour (based on definition quality); and Auto: adjusts automatically based on the current internet connection speed. To adjust the data settings in a web browser, go to your account page > Profile & Parental Controls > Profile > Playback Settings > Change.

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BANDWIDTH在剑桥英语词典中的解释及翻译

BANDWIDTH在剑桥英语词典中的解释及翻译

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bandwidth 在英语中的意思

bandwidthnoun [ C usually singular or U ] uk

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/ˈbænd.wɪtθ/ us

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/ˈbænd.wɪtθ/

bandwidth noun [C usually singular or U]

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a measurement of the amount of information that can be sent between computers, through a phone line, etc.: The system will handle signals that need high bandwidth, for instance those that encode TV pictures. high-bandwidth services/applications

the ability or time to deal with a situation, especially one that involves a large amount of information or a number of problems: I don't have the bandwidth to read stuff I know isn't going to lead to productive discussion. If people misreport or misrepresent my arguments, I am using more of my bandwidth to correct the misreporting.

更多范例减少例句Tasks like simultaneously streaming several different video signals over a wireless connection require more bandwidth.Once software begins to use the extra bandwidth, you'll likely be glad you have it. There's enough bandwidth to let you surf, stream and down- load all at the same time.

“SMART 词汇”：相关单词和短语

Communications - by telephone

0800 number

3G

4G

5G

access code

aeroplane mode

airplane mode

area code

buzz

caller ID

Directory Enquiries

ISDN

patch someone through

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phone mast

pick

pick someone/something up

speakerphone

telephone

unlisted

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你还可以在这些话题中找到相关的词、词组和同义词：

Skill, talent and ability

bandwidth noun [C usually singular or U]

(RADIO)

the range of frequencies used to send information over a distance using phone wires

in radio, the width of a particular waveband

“SMART 词汇”：相关单词和短语

Communications - by telephone

0800 number

3G

4G

5G

access code

aeroplane mode

airplane mode

area code

buzz

caller ID

Directory Enquiries

ISDN

patch someone through

phone in

phone mast

pick

pick someone/something up

speakerphone

telephone

unlisted

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你还可以在这些话题中找到相关的词、词组和同义词：

Broadcasting: radio

(bandwidth在剑桥高级学习词典和同义词词典中的解释 © Cambridge University Press)

bandwidth | 美式英语词典

bandwidthnoun [ U ] us

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/ˈbænd·wɪtθ, -wɪdθ/

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the amount of information that can be sent over a network connection at one time: These streaming applications swallow enormous chunks of bandwidth for long periods of time.

Bandwidth is also the amount of time, information, or influence that someone has: He has more bandwidth (= more influence) than any presidential adviser has ever had in history.

(bandwidth在剑桥学术词典中的解释 © Cambridge University Press)

bandwidth | 商务英语

bandwidthnoun [ C, usually singular ]

  COMMUNICATIONS uk

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/ˈbændwitθ/ us

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the amount of information that can be sent between computers, over a phone line, using radio signals, etc. in a particular amount of time: As prices for telecommunications services fall, demand for high bandwidth services is increasing.

the range of frequencies (= numbers of waves produced in a particular amount of time) used to send information over a distance using phone lines or radio signals: Text messages require less bandwidth than phone calls.

也请参见

channel capacity

(bandwidth在剑桥商务英语词典中的解释 © Cambridge University Press)

bandwidth的例句

bandwidth

Suggested formulae for calculating auditory-filter bandwidths and excitation patterns.

来自 Cambridge English Corpus

Target and background fields were defined by circular field stops, and their wavelengths were selected by interference filters with full-width at half-maximum bandwidths of between 7 and 11 nm.

来自 Cambridge English Corpus

Spectral bandwidths of colour detection mechanisms revisited.

来自 Cambridge English Corpus

Spectral bandwidths for the detection of color.

来自 Cambridge English Corpus

Spectral bandwidths for detection of color.

来自 Cambridge English Corpus

Was he referring to the auction of digital bandwidths?

来自 Hansard archive

该例句来自Hansard存档。包含以下议会许可信息开放议会许可v3.0

Copper wire will be replaced where freedom from electrical interference and wider bandwidths are required.

来自 Hansard archive

该例句来自Hansard存档。包含以下议会许可信息开放议会许可v3.0

Details of the three bandwidths and the amount each authority will use to calculate its share of the quantum for basic/attendance allowance are given below.

来自 Hansard archive

该例句来自Hansard存档。包含以下议会许可信息开放议会许可v3.0

In non-broadband-enabled areas in my constituency, such bandwidths might be provided through a private circuit, which helps the school but does nothing for the rest of the village.

来自 Hansard archive

该例句来自Hansard存档。包含以下议会许可信息开放议会许可v3.0

To achieve greater bandwidths multiple /4 coupling sections are used.

来自 Wikipedia

该例句来自维基百科，在CC BY-SA许可下可重复使用。

A single /4 coupled section is good for bandwidths of less than an octave.

来自 Wikipedia

该例句来自维基百科，在CC BY-SA许可下可重复使用。

Given their substantially greater bandwidths, they also tend to be noisier.

来自 Wikipedia

该例句来自维基百科，在CC BY-SA许可下可重复使用。

A thorough presentation of filtering semantics and design choices is given, focusing on network bandwidth efficiency but neglecting any engineering support.

来自 Cambridge English Corpus

As each partition can support network traffic independent of all the other partitions, the total bandwidth or total network capacity is available in each partition.

来自 Cambridge English Corpus

Beyond the atmosphere, stability becomes a matter of active control with sufficient bandwidth.

来自 Cambridge English Corpus

查看bandwidth的所有示例

示例中的观点不代表剑桥词典编辑、剑桥大学出版社和其许可证颁发者的观点。

bandwidth的发音是什么？

 

B1

bandwidth的翻译

中文（繁体）

頻寬, 處理大量資訊或復雜情況所需的時間、精力和綜合能力, 頻帶…

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中文（简体）

带宽, 处理大信息或复杂情况所需的时间、精力和综合能力, 频带…

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西班牙语

ancho de banda digital, ancho de banda…

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葡萄牙语

largura da banda, largura de barramento, largura de banda…

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土耳其语

俄语

przepustowość, szerokośćpasma…

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dalga genişliği, bant aralığı…

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а…

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bandsman

bandstand

bandura

bandwagon

bandwidth

bandy

bandy something about

bandy something around

bandy words idiom

“每日一词”

veggie burger

UK

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/ˈvedʒ.i ˌbɜː.ɡər/

US

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/ˈvedʒ.i ˌbɝː.ɡɚ/

a type of food similar to a hamburger but made without meat, by pressing together small pieces of vegetables, seeds, etc. into a flat, round shape

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March 06, 2024

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March 04, 2024

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英语 

 

Noun 

bandwidth (INFORMATION)

bandwidth (RADIO)

美式 

 Noun

商务 

 Noun

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_百度百科 网页新闻贴吧知道网盘图片视频地图文库资讯采购百科百度首页登录注册进入词条全站搜索帮助首页秒懂百科特色百科知识专题加入百科百科团队权威合作下载百科APP个人中心网络带宽播报讨论上传视频指在单位时间内能传输的数据量收藏查看我的收藏0有用+10网络带宽是指在单位时间（一般指的是1秒钟）内能传输的数据量。网络和高速公路类似，带宽越大，就类似高速公路的车道越多，其通行能力越强。网络带宽作为衡量网络特征的一个重要指标，日益受到人们的普遍关注。它不仅是政府或单位制订网络通信发展策略的重要依据，也是互联网用户和单位选择互联网接入服务商的主要因素之一。所谓带宽，是“频带宽度”的简称，原是通讯和电子技术中的一个术语，指通讯线路或设备所能传送信号的范围。而网络中的带宽是指在规定时间内从一端流到另一端的信息量，即数据传输率。带宽对模拟信号和数字信号有两种基本的应用，在本文中所说的带宽均是指数字信号。 [1]中文名网络带宽外文名Network Bandwidth属    性联网方式代    指数据传输率基本单位bits per second带宽的单位bps，Kbps，Mbps，Gbps，Tbps影响因素网络设备与周边国家比国内网络提速，势在必行目录1数字信息2含义3计算方法4吞吐量5影响因素6总结7速度比较数字信息播报编辑数字信息流的基本单位是bit（比特），时间的基本单位是s（秒），因此bit/s（比特/秒）是描述带宽的单位，1bit/s是带宽的基本单位。不难想象，以1bit/s的速率进行通信是如何的缓慢。幸好我们可以使用通信速率很快的设备，56K的调制解调器利用电话线拨号上网，其带宽是56000bit/s（1K=1000bit/s）， 电信ADSL宽带上网在512Kbit/s至10Mbit/s间，而以太网则达10Mbit/s以上（1Mbit/s=1000*1000bit/s=10^6bit/s）。含义播报编辑带宽是一个非常有用的概念，在网络通信中的地位十分重要。带宽的实际含义是在给定时间等条件下流过特定区域的最大数据位数。虽然它的概念有点抽象，但是可以用比喻来帮助理解带宽的含义。把城市的道路看成网络，道路有双车道、四车道也许是八车道，人们驾车从出发点到目的地，途中可能经过双车道、四车道也许是单车道。在这里，车道的数量好比是带宽，车辆的数目就好比是网络中传输的信息量。我们再用城市的供水网来比喻，供水管道的直径可以衡量运水的能力，主水管直径可能有2m，而到家庭的可能只有2cm。在这个比喻中，水管的直径好比是带宽，水就好比是信息量。使用粗管子就意味着拥有更宽的带宽，也就是有更大的信息运送能力。计算方法播报编辑在计算机网络、IDC机房中，其网络传输速率的单位用b/s(比特每秒)(或bit/s，有时也写作bps，即bit per second)表示。在通信领域和计算机领域，应特别注意数量单位“千”、“兆”、“吉”等的英文缩写所代表的数值。计算机中的数量单位用字节作为度量单位，“千字节”的“千”用大写K表示，它等于210，即1024，而不是1000。在实际上网应用中，下载软件时常常看到诸如下载速度显示为176KB/s，103KB/s等宽带速率大小字样，因为ISP提供的线路带宽使用的单位是比特（bit），而一般下载软件显示的是字节（Byte）（1Byte=8bit），所以要通过换算，才能得实际值。我们以1M宽带为例，按照换算公式换算一下：1Mb/s=1024Kb/s=1024/8KB/s=128KB/s理论上：2M（即2Mb/s）宽带理论速率是：256KB/s，实际速率大约为150~240KB/s；（其原因是受用户计算机性能、网络设备质量、资源使用情况、网络高峰期、网站服务能力、线路衰耗，信号衰减等多因素的影响而造成的）。4M（即4Mb/s）的宽带理论速率是：512KB/s，实际速率大约为200~440KB/s 。上行速率是指用户电脑向网络发送信息时的数据传输速率，下行速率是指网络向用户电脑发送信息时的传输速率。比如用FTP上传文件到网上去，影响上传速度的就是“上行速率”；而从网上下载文件，影响下载速度的就是“下行速率”。当然，在实际上传下载过程中，线路、设备(含计算机及其他设备)等的质量也会对速度造成或多或少的影响。吞吐量播报编辑假如你单位已经安装了宽带业务，或小区宽带已经连到你家，你准备下载一个程序、一个网页或一部电影。也许你认为正在使用服务商声称的全部带宽，其实不然，这就不得不涉及到另一个概念——吞吐量。吞吐量是指在规定时间、空间及数据在网络中所走的路径（网络路径）的前提下，下载文件时实际获得的带宽值。由于多方面的原因，实际上吞吐量往往比传输介质所标称的最大带宽小得多。 [2]影响因素播报编辑网络带宽影响网络中带宽和吞吐量的主要因素有：1、网络设备（交换机、路由器、集线器）；2、拓扑结构（即网络构造形状，如星型、环状）；3、数据类型；4、用户的数量；5、客户机与服务器（如系统总线、磁盘性能、网络适配器、硬件防火墙）；6、电力系统和自然灾害引起的故障率。当设计一个网络时，应该重点考虑带宽的理论值，即在给定的条件下，理论上所具备的最大数据传输位数。设计的网络的速度应与介质所允许的速度相当，让用户使用网络时，应该考虑的是吞吐量，即用户是否满意实际获得的带宽值。当构建网络时应考虑的重要因素是介质的选择，这又和用户所需要的文件下载量有关，文件越大，需要的时间越多。有一个公式：预计下载时间=传输文件尺寸/带宽。在不考虑影响带宽的各种因素下，根据此公式可以粗略估计已选择的介质传输文件所需要的时间。总结播报编辑在网络通信中，个人或组织在使用网络时总是希望带宽越来越宽，特别是Internet的使用，对数据传输的要求呈现出爆炸性的增长，因此对带宽的要求也日甚一日。当今，新一代多媒体、影像传输、数据库、网络电视的信息量猛增使得带宽成为了严重的瓶颈，迫使以太网向更高的速度发展。各种开发光纤网带宽的技术正在研究和使用中。光纤通信技术是比较重要的通信技术之一，其能够直接决定网络通信的效果和速度，还可以影响通信带宽以及数据传输的流畅性，其对于信息建设具有至关重要的作用。 [3]因此，了解带宽的作用无疑将节约大量的资金，作为一名网络设计人员，带宽是主要的设计点。作为网络专业人士，带宽和吞吐量是分析网络运行情况的要素。互联网日益强大，网民人数不断增加，伴随而来的是互联网公众化时代的到来。人们对互联网的需求不再是单一地浏览网页、查看新闻，而是提出了多样化的应用需求。网络游戏、在线影视、远程办公、网络电视等形式的出现虽然极大地丰富了人们的生活，但同时也给互连网的带宽提出了更加高的要求。速度比较播报编辑各国网速对比图与周边国家相比，国内网络提速，势在必行。新手上路成长任务编辑入门编辑规则本人编辑我有疑问内容质疑在线客服官方贴吧意见反馈投诉建议举报不良信息未通过词条申诉投诉侵权信息封禁查询与解封©2024 Baidu 使用百度前必读 | 百科协议 | 隐私政策 | 百度百科合作平台 | 京ICP证030173号 京公网安备110000020000

What is network bandwidth and how is it measured?

What is network bandwidth and how is it measured?

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Definition

bandwidth (network bandwidth)

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By

Andrew Froehlich,

West Gate Networks

Kevin Ferguson

What is network bandwidth?

Network bandwidth is a measurement indicating the maximum capacity of a wired or wireless communications link to transmit data over a network connection in a given amount of time. Typically, bandwidth is represented in the number of bits, kilobits, megabits or gigabits that can be transmitted in 1 second. Synonymous with capacity, bandwidth describes data transfer rate. Bandwidth is not a measure of network speed -- a common misconception.

How does bandwidth work?

The more bandwidth a data connection has, the more data it can send and receive at one time. In concept, bandwidth can be compared to the volume of water that can flow through a pipe. The wider the pipe's diameter, the more water can flow through it at one time. Bandwidth works on the same principle. The higher the capacity of the communication link, the more data can flow through it per second.

The cost of a network connection goes up as bandwidth increases. Thus, a 1 gigabit per second (Gbps) Dedicated Internet Access (DIA) link will be more expensive than one that can handle 250 megabits per second (Mbps) of throughput.

Bandwidth vs. speed

The terms bandwidth and speed are often used interchangeably but not correctly. The cause of the confusion may be due, in part, to advertisements by internet service providers (ISPs) that conflate the two by referring to greater speeds when they truly mean bandwidth.

Essentially, speed refers to the rate at which data can be transmitted, while the definition of bandwidth is the capacity for that speed. To use the water metaphor again, speed refers to how quickly water can be pushed through a pipe; bandwidth refers to the quantity of water that can be moved through the pipe over a set time frame.

Why bandwidth is important

Bandwidth is not an unlimited resource. In any given deployment location, such as a home or business, there is only so much capacity available. Sometimes, this is due to physical limitations of the network device, such as the router or modem, cabling or wireless frequencies being used. Other times, bandwidth is intentionally rate-limited by a network administrator or internet or wide area network (WAN) carrier.

Multiple devices using the same connection must share bandwidth. Some devices, such as TVs that stream 4K video, are bandwidth hogs. In comparison, a webinar typically uses far less bandwidth. Although speed and bandwidth are not interchangeable, greater bandwidth is essential to maintain tolerable speeds on multiple devices. To help illustrate this, here's the average bandwidth consumed for various services:

The average bandwidth or data transfer rate required by services

How to measure bandwidth

While bandwidth is traditionally expressed in bits per second (bps), modern network links now have far greater capacity, which is why bandwidth is now more often expressed as Mbps or Gbps.

Bandwidth connections can be symmetrical, which means the data capacity is the same in both directions -- upload and download -- or asymmetrical, which means download and upload capacity are not equal. In asymmetrical connections, upload capacity is typically smaller than download capacity; this is common in consumer-grade internet broadband connections. Enterprise-grade WAN and DIA links more commonly have symmetrical bandwidth.

Considerations for calculating bandwidth

Technology advances have made some bandwidth calculations more complex, and they can depend on the type of network link being used. For example, optical fiber using different types of light waves and time-division multiplexing can transmit more data through a connection at one time compared to copper Ethernet alternatives, which effectively increases its bandwidth.

In mobile data networks, such as Long-Term Evolution, or LTE, and 5G, bandwidth is defined as the spectrum of frequencies that operators can license from the Federal Communications Commission and the National Telecommunications and Information Administration for use in the U.S. This spectrum cannot be legally used by anyone other than the business that owns the license to it. The carrier can then use wireless technologies to transport data across that spectrum to achieve the greatest bandwidth the hardware can provide.

Wi-Fi spectrum, on the other hand, is considered to be unlicensed. Thus, anyone with a Wi-Fi access point (AP) or Wi-Fi router can create a wireless network. The caveat is that the spectrum is not guaranteed to be available. Thus, Wi-Fi bandwidth can suffer when there are other Wi-Fi APs attempting to use some or all of the same frequencies.

Effective bandwidth -- which is the highest reliable transmission rate a link can provide on any given transport technology -- can be measured using a bandwidth test. During a bandwidth test, the link's capacity is determined by repeatedly measuring the time required for a specific file to leave its point of origin and successfully download at its destination.

After determining bandwidth consumption across the network, it is then necessary to see where applications and data reside and calculate their average bandwidth needs for each user and session.

To understand how much bandwidth a network uplink or internet broadband requires, follow these four steps:

Determine which applications will be in use.

Determine the bandwidth requirements of each application.

Multiply the application requirements of each application by the number of expected simultaneous users.

Add all application bandwidth numbers together.

To determine bandwidth needs for public or private clouds across internet or WAN links, the same calculation applies. The difference, however, is that available bandwidth on a local area network or wireless LAN is typically far greater compared to WAN or DIA connections. Thus, accurately assessing bandwidth requirements is critical, as is monitoring link utilization over time. Monitoring the amount of bandwidth used throughout the day, week, month or year can help network engineers determine whether a WAN/DIA link has sufficient bandwidth -- or if a bandwidth upgrade is needed.

When there is insufficient bandwidth on a network, applications and services perform poorly.

Factors affecting network performance

The maximum capacity of a network connection is only one factor that affects network performance. Packet loss, latency and jitter can all degrade network throughput and make a high-capacity link perform like one with less available bandwidth.

An end-to-end network path usually consists of multiple connections, each with different bandwidth capacity. As a result, the link with the lowest bandwidth is often described as the bottleneck because it can limit the overall capacity of all connections in the path.

Many enterprise-grade networks are deployed with multiple aggregated links acting as a single logical connection. If, for example, a switch uplink uses four aggregated 1 Gbps connections, it has an effective throughput capacity of 4 Gbps. However, if two of those links were to fail, the bandwidth limit would drop to 2 Gbps.

Bandwidth on demand

Bandwidth for internet or WAN links is typically sold at a set price per month. However, bandwidth on demand -- also called dynamic bandwidth allocation or burstable bandwidth -- is an alternative model that enables subscribers to increase the amount of available bandwidth at specific times or for specific purposes. Bandwidth on demand is a technique that can provide additional capacity on a communications link to accommodate bursts in data traffic that temporarily require more bandwidth.

Rather than overprovisioning the network with expensive dedicated links year-round, bandwidth on demand is frequently used in WANs to increase capacity as needed for a special event or time of day when traffic is expected to spike. An online flower retailer, for example, may only need to increase its capacity in the weeks leading up to Mother's Day. Bandwidth on demand enables enterprises to only pay for the additional bandwidth they consume over a shorter period of time.

Bandwidth on demand is available through many internet and WAN service providers. Depending on the network link a customer currently has in use, a provider may be able to provision additional capacity on demand using the existing connection. For example, a 100 Mbps link might be able to burst up to 1 Gb because the service provider's connection has available capacity. If a customer needed more than the absolute maximum bandwidth available on that link, another physical connection would be required.

Occasionally, a service provider will enable customers to burst above their subscribed bandwidth cap without charging additional fees. However, if customers were to regularly sustain more than 100 Mbps using the burst feature, they are commonly billed by the service provider using 95th percentile calculations.

SD-WAN eases dedicated bandwidth capacity planning processes

Software-defined WAN (SD-WAN) technology can provide customers with extra capacity by balancing traffic across multiple WAN and DIA connections rather than a single connection. SD-WAN deployments often use a Multiprotocol Label Switching, or MPLS, connection or other types of dedicated transport links in combination with a lower-cost broadband internet or cellular connection.

How do you optimize and monitor bandwidth use?

Network engineers have several options available when a network link becomes congested. The most frequent choice is to increase bandwidth. This can be achieved by upgrading the physical throughput capabilities of the link or through port aggregation and load balancing to logically split traffic across multiple links. However, sometimes these techniques are not possible.

ISPs or network administrators may also intentionally adjust the speed -- up or down -- of data traveling over the network, a measure known as bandwidth throttling. There are different reasons for bandwidth throttling, including limiting network congestion, particularly on public access networks. ISPs may use throttling to reduce bandwidth use by a particular user or class of users. For example, with tiered pricing, a service provider can offer a menu of upload and download bandwidth. ISPs can also throttle bandwidth to even out usage across all users on the network.

The use of bandwidth throttling on the internet has been criticized by net neutrality advocates, who say that the practice can be misused for political or economic reasons and that it unfairly targets segments of the population.

A speed test can be run to see if an ISP is throttling bandwidth. Speed tests measure the speed between a device and a test server using a device's internet connection. ISPs offer speed tests on their own websites, and independent tests are also available from services such as Speedtest. Because many factors can affect the results of a speed test, it is generally recommended to perform multiple tests at different times of the day and engage different servers available through the speed test site. It is also recommended to conduct a speed test over a wired connection.

data transfer throttling intentionally restricts the amount of data sent or received over a network, particularly for the purposes of preventing spam or bulk email transmission through a server. It can be considered another form of bandwidth throttling. If it is implemented on a large enough scale, data transfer throttling can control the spread of computer viruses, worms or other malware through the internet.

Network bandwidth monitoring tools are available to help identify performance issues, such as a faulty router or a malware-infected computer that is participating in a distributed denial-of-service attack. As noted earlier, bandwidth monitoring can also help network administrators better plan for future network growth -- seeing where in the network bandwidth is most needed. Monitoring tools can also help administrators see if their ISP is fulfilling the service-level agreement in their contract.

Learn what network capacity planning best practices organizations are putting in place now as pandemic concerns begin to subside and more employees are returning to the office.

This was last updated in May 2021

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