Content
- What is the role of bandwidth in a computer system?
- Expression of bandwidth
- Measure the bandwidth
- Bandwidth, speed and throughput
- Why measure bandwidth
- Buy bandwidth
- Bandwidth issues
- Resolving bandwidth issues
What is the role of bandwidth in a computer system?
Bandwidth is the amount of data that can be transferred from one point to another on a network in a defined amount of time. Typically, it is expressed as a bit rate, or bitrate, measured in bits per second (bps). This figure corresponds to the transmission capacity of a connection and considerably influences the quality and speed of a network. There are several methods for measuring bandwidth. Some are used to calculate the data flow in real time, while others measure the maximum flow, the average flow, or what is considered to be the good flow. The notion of bandwidth plays a preponderant role in other technological fields. In signal processing, for example, it describes the difference between the high and low frequencies of a transmission such as a radio signal, and is generally measured in hertz (Hz).
Bandwidth Expression
Originally, bandwidth was expressed in bits per second, an abbreviated unit in bps . However, today’s networks offer significantly higher throughput which is more convenient to translate using larger units. It is therefore common to see numbers with prefixes from the metric system, such as Mbps, (megabits per second), Gbps (gigabits per second), or Tbps (terabits per second). As a reminder:
K = kilo = 1,000 bits
M = mega = 1,000 kilo = 1,000,000 bits
G = giga = 1,000 mega = 1,000,000,000 bits
T = tera = 1,000 gigas = 1,000,000,000,000 bits
After the terabit comes the petabit, the exabit, the zettabit, and the yottabit, which each represent an additional power.
Bandwidth can also be expressed in bytes per second, a unit which is generally designated by the symbol B. Thus, 10 megabytes per second would be noted as 10 MB / s or 10 MBps.
One byte is equivalent to eight bits.
Thus, 10 MB / s = 80 mb / s.
Bytes and bits use the same metric prefixes. In fact, 1 TB / s is one terabyte per second.
Measure bandwidth
To measure bandwidth, most of the time, we use software or firmware that we associate with a network interface. Among the most widely used measurement tools, we can cite, among others, the Test TCP utility (TTCP) or PRTG Network Monitor.
TTCP measures the speed of an IP network between two hosts; one acts as recipient, and the other as sender. Each part displays the number of bytes transmitted and the time it takes for each packet to go one way.
PRTG offers a graphical interface and diagrams to measure the evolution of bandwidth over extended periods and to account for traffic between different interfaces.
To measure bandwidth, the total amount of traffic sent and received over a period of time is usually counted. The resulting measurements are then expressed as a number per second.
Bandwidth Monitoring
There are several ways of looking at the flow of data over a network. The speed of a network is defined as the bit rate of the circuit, determined by the speed of the physical signal of the medium.
Bandwidth represents the capacity of the physical circuit to transmit data and is determined by the amount of network capacity available depending on the connection. Where a Gigabit Ethernet (GbE) network connection will display data transfer rates of one gigabit per second, the bandwidth available to a computer connected to the web via a Fast Ethernet card will be limited to 100 Mbps.
The speed corresponds to the rate of successful transmissions, while the bandwidth is the sum of the data that passes through the network interface, whether or not it is transmitted. This is the reason why the speed is always lower than the bandwidth.
Why measure bandwidth
It may be necessary to measure the bandwidth for several reasons . If the usable bandwidth is lower than the theoretical maximum speed, it is probably that the network is affected by problems, a fortiori when it varies considerably from one area to another of a network where it is supposed be distributed evenly.
Bandwidth management
In order to manage bandwidth optimally, or to control quality of service (QoS), it is first important to understand what bandwidth is used. Once this has been determined, it should be measured continuously to meet the needs of all users.
Bandwidth throttling
After identifying trends in bandwidth consumption and determining whether certain users or certain applications are monopolizing resources to the point where others have to settle for reduced network performance, there are different tools that can be used to limit the amount of bandwidth available to them.
Buy bandwidth
Bandwidth is usually purchased from telecom operators. Most of the time, these boast a theoretical maximum speed, which means that the client can benefit from a transfer rate less than or equal to, for example, 40 MB / s, but that it should not expect it to systematically reach this velocity when the connection is used. In practice, the speed may be higher or lower than this value depending on the time of day, just as it may vary in certain circumstances. Businesses also buy speed from telecom operators. However, contracts intended for professionals are generally accompanied by quantified performance commitments, in particular concerning the minimum usable bandwidth, the minimum availability rate, and other parameters.
Bandwidth issues
Lack of bandwidth
While current protocols do a pretty good job of preventing packet loss, a lack of bandwidth can still slow operations down to the point of preventing execution, which can lead to session expiration or other problems. origin of the crash of applications or databases. When backing up or copying data over a network, lack of bandwidth can slow backups considerably to the point where they overlap with other batch processes or overflow with working hours.
For users who want to make phone calls over their network, that is, VoIP (Voice over Internet Protocol), missing bandwidth can affect call quality. In fact, most VoIP systems adapt the definition of a call to the available bandwidth. If there is not enough, the call may sound metallic or reverberate. And if the quality is too poor, the call can even be disrupted by blackouts that prevent hearing parts of the conversation. Video calls require even more bandwidth. When this is missing, the conversation suffers from degraded sound and the video is found to be choppy or of poor quality.
Excess bandwidth
Excess bandwidth poses few technical problems. On the other hand, high capacity bandwidth represents a cost. So it is not always economical to have too much.
Latency
Network design and infrastructure can also give rise to bandwidth issues. Latency measures delays on the network which can slow down the speed or the useful speed. A network with low latency will experience fairly short delays, and vice versa. High latency prevents data from fully exploiting network capacity, which reduces bandwidth.
Bandwidth troubleshooting
Identifying and resolving bandwidth issues improves network performance without the need for costly upgrades.
Ping and Traceroute
Tools like ping and traceroute can solve rudimentary problems. Sending a ping signal to a test server, for example, will provide information on the time required for the data to be routed and received, but also on the average delay of the round trip. If the response times are high, this means that the network is marked by high latency.
The traceroute tool is used to determine if there are enough individual network connections, or hops, on the connection path. In addition, traceroute specifies the time taken by each hop. Above average time on a hop is a sign of a problem.
TTCP
TTCP measures the time required for data to travel from one network interface to another with a receiver at the other end. This eliminates the return trip from the calculation and allows you to quickly locate problems. If the measured bandwidth is lower than normal, other measures can isolate the problem. Will a measurement made on another interface on the same network go faster? If so, what is the difference between the two systems? By measuring bandwidth continuously, administrators can target network bottlenecks.
PRTG Network Monitor
With an interface that aggregates data and converts it to graphics, PRTG can also help you resolve bandwidth problems that are not structural. For example, by measuring bandwidth consumption over the long term, we can see that some users or certain applications sometimes consume an abnormally high amount of bandwidth and cause network congestion which affects process response times and other users’ applications.
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