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IT Explained:What is bandwidth?Bandwidth is measured as the amount of data that can be transferred from one point to another within a network in a specific amount of time. Typically, bandwidth is expressed as a bitrate and measured in bits per second (bps). The term bandwidth refers to the transmission capacity of a connection and is an important factor when determining the quality and speed of a network or the internet connection. There are several different ways to measure bandwidth. Some measurements are used to calculate current data flow, while others measure maximum flow, typical flow, or what is considered to be good flow. Bandwidth is also a key concept in several other technological fields. In signal processing, for example, it is used to describe the difference between the upper and lower frequencies in a transmission such as a radio signal and is typically measured in hertz (Hz). Bandwidth can be compared to water flowing through a pipe. Bandwidth would be the rate at which water (data) flows through the pipe (connection) under various circumstances. Instead of bits per second, we might measure gallons per minute. The amount of water that possibly can flow through the pipe represents the maximum bandwidth, while the amount of water that is currently flowing through the pipe represents the current bandwidth. Expressing bandwidth
K = kilo = 1,000 bits After terabit, there are petabit, exabit, zettabit, and yottabit, each representing an additional power of 10. Bandwidth can also be expressed as bytes per second. This is commonly denoted with a capital B. For example, 10 megabytes per second would be expressed as 10 MB/s or 10 MBps. One byte is eight bits. Thus, 10 MB/s = 80 Mb/s. The same metric prefixes can be used with bytes as with bits. Thus, 1 TB/s is one terabyte per second. Are you getting the full bandwidth? Find out with PRTG Network Monitor!
Measuring bandwidth
TTCP measures throughput on an IP network between two hosts. One host is the receiver, the other the sender. Each side displays the number of bytes transmitted and the time for each packet to complete the one-way trip. PRTG provides a graphical interface and charts for measuring bandwidth trends over longer periods of time, and can measure traffic between different interfaces. Typically, to measure bandwidth, the total amount of traffic sent and received across a specific period of time is counted. The resulting measurements are then expressed as a per-second number. Another method of measuring bandwidth is to transfer a file, or several files, of known size and count how long the transfer takes. The result is converted into bps by dividing the size of the files by the amount of time the transfer required. Most internet speed tests use this method to calculate the connection speed of a user’s computer to the internet. While there is no way to measure total available bandwidth, there are many ways to define measured bandwidth, depending on the need. Theoretical maximum – The highest transmission rate under ideal circumstances. The theoretical maximum transfer rate cannot be achieved in actual installations. Typically, the theoretical maximum is only used for comparison as a way of determining how well a connection is functioning compared to its theoretical maximum potential. Effective bandwidth – The highest reliable transmission rate. Always lower than the theoretical maximum. Sometimes considered the best usable bandwidth. Necessary for understanding the amount of traffic a connection can support. Throughput – The average rate of successful data transfer; useful for understanding the typical or usual speed of a connection. Throughput is the size of the transfer divided by the time it takes for the transfer to complete. Measured in bytes per second, throughput can be compared to the effective bandwidth and the theoretical maximum as a way of determining how well the connection is performing. Goodput – Measures the amount of useful data that is transferred, excluding undesirable data such as packet retransmissions or protocol overhead. Goodput is calculated by dividing the size of the transferred file by the amount of time the transfer took. Total transfer method – Counts all traffic across a period of set time, typically a month. This is most useful for billing based on how much bandwidth is used. 95th percentile method – To avoid having bandwidth measurements skewed by spikes in usage, carriers often use the 95th percentile method. The idea is to continuously measure bandwidth usage over time, and then remove the top 5 percent of use. This is useful for billing based on how much bandwidth is ‘normally’ used in a set period. In real world networks, bandwidth varies over time depending on use and network connections. As a result, a single bandwidth measurement says very little about actual bandwidth usage. A series of measurements can be more useful when determining averages or trends. Bandwidth vs. speed vs. throughput
Bandwidth is how much of the physical circuit’s capacity can be used to transmit data and is determined by how much of the network capacity is available based on the connection. While a Gigabit Ethernet network connection would allow for 1 Gbps, the bandwidth available to a computer connected by a Fast Ethernet card would only be 100 Mbps. Throughput is the rate of successful transmission, while bandwidth is a calculation of the amount of data that passes the network interface, regardless of whether the data results in a successful transmission. As such, throughput is always lower than bandwidth. Why measure bandwidth
Additionally, measuring bandwidth is necessary to ensure that any paid connections are living up to their promise. Home users may run an online bandwidth test such as the DSLReports speed test to see just how much of that “up to 40 Mb/s” connection their internet service provider (ISP) charges them for they actually get to use. Corporate connections might be better served by measuring throughput between offices connected by a carrier-leased line connection. Bandwidth managementIn order to implement proper bandwidth management, or Quality of Service (QoS) controls, one must first understand what bandwidth is used. Once determined, a continuous measurement will ensure that all users get the necessary bandwidth. Bandwidth throttlingOnce bandwidth usage patterns are understood, and if specific users or applications are degrading network performance for others, tools can be used to limit the amount of bandwidth they are using. Bandwidth maximumsSome types of connections have a maximum defined bandwidth. Actual bandwidth depends on many factors including environment, cabling, and usage, and is usually less than the theoretical maximum. Wired bandwidth standards for connections
Wireless network standard maximum download speeds Wireless network connection speeds vary widely based on the conditions of the connection. The numbers below are the maximum bandwidth speeds according to the standard or specification.
WiFi 802.11bf: New applications for wireless devices The WiFi standard 802.11bf will not only be used for communication but also as a complete sensing paradigm. This will expand the possibilities of WiFi and e.g. detect which people or objects are moving within its range of motion. The upcoming version can be used in industrial and commercial environments in manufacturing systems, corporate networks, and test and measurement equipment. Purchasing bandwidth
Additionally, bandwidth metering may be used to charge for specific usage rather than a full connection. For example, a website owner may pay the website host only for the amount of bandwidth used by that specific website over a period of time, such as a monthly billing period. Bandwidth issues
|
0.5 Mbps | |
Web Browsing | 0.5 Mbps to 1.0 Mbps |
Streaming Music | 0.5 Mbps |
Phone Calls (VoIP) | 0.5 Mbps |
Streaming Videos | 0.7 Mbps |
Streaming Movies (Non-HD) | 1.5 Mbps |
Streaming HD Quality Movies | 4 Mbps |
Basic Video Conferencing | 1 Mbps |
HD Video Conferencing | 4 Mbps |
Internet Connected Game Console | 1 Mbps |
Online Multiplayer HD Gaming | 4 Mbps |
Table of FCC minimum required download speed
Too much bandwidth
There a few technical issues caused by too much bandwidth. Higher capacity bandwidth, however, typically costs more. Thus, too much bandwidth may not be cost effective.
Latency
Network design and infrastructure can create bandwidth issues as well. Latency measures the delays on a network that may be causing lower throughput or goodput. A low latency network has short delays, while a high latency network has longer delays. High latency prevents data from fully using the network’s capabilities, therefore decreasing the bandwidth.
Troubleshooting bandwidth issues
Finding and remedying bandwidth issues helps improve network performance without costly upgrades.
Ping and traceroute
Tools such as Ping and traceroute can help troubleshoot
basic issues.
Pinging a test server, for example, will return information on how quickly data can be sent and received, as well as average round trip times. High ping times indicate higher latency in the network.
The traceroute tool can help determine if there are too many individual network connections, or hops, along the connection path. In addition, traceroute returns the time taken by each hop. A longer time on a single hop may pinpoint the source of an issue.
TTCP
TTCP measures the time it takes for data to travel from one network interface to another with a receiver on the other end. This eliminates the return trip from the calculation and may help pinpoint issues quickly. If the measured bandwidth is less than expected, further measurements can isolate the issue. Does a measurement to another interface on the same network work faster? If so, where is the difference between the two systems? By continually measuring bandwidth, administrators can target the bottlenecks in the network.
PRTG Network Monitor
With its data gathering and graphing interface, PRTG can also help troubleshoot bandwidth problems that are not related to design. For example, by measuring bandwidth usage over time, it may be determined that certain users or applications are sometimes using higher amounts of bandwidth and causing network congestion and slowing network responsiveness and internet speed for other users.
Find out more about bandwidth monitoring with PRTG >
Are you getting the full bandwidth? Find out with PRTG Network Monitor!
Are your service providers giving you the full bandwidth? Is your bandwidth stable? Are there any bandwidth hogs? Find out by using the professional Bandwidth Monitoring Tool PRTG.
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