Network Performance
Network performance refers to metrics that show how users rate a network’s service quality.
A network’s performance can be measured in a variety of ways because every network is unique in its architecture and nature. In addition to being measured, performance can also be simulated and modeled. Using a network simulator or state transition diagrams to simulate queuing performance are two examples of this.
Performance measures
The following actions are frequently seen as crucial:
- The highest speed at which data may be transported is known as bandwidth, and it is generally measured in bits per second.
- The real rate at which information is conveyed is called throughput.
- Latency is the amount of time that passes between sending and receiving data before it is decoded; it is mostly determined by the signal’s travel time and the processing speed of any nodes the data passes through.
- Jitter variation in the information recipient’s packet delay
- Error rate: the proportion or portion of the total delivered data that contains corrupted bits
Bandwidth
The achievable signal-to-noise ratio and available channel bandwidth are what determine the maximum throughput. In general, the Shannon-Hartley Theorem prevents sending more data than is feasible.
Throughput
The number of messages successfully delivered in a unit of time is known as throughput. Available bandwidth, available signal-to-noise ratio, and hardware constraints all affect throughput. To separate the concepts of throughput and latency, throughput shall be defined in this article as the amount of data received at the receiver from the moment the first bit arrives. The terms “throughput” and “bandwidth” are sometimes used interchangeably in discussions of this kind.
The time frame used to measure throughput is called the Time Window. Selecting a suitable time window is frequently the most important factor in throughput calculations. Whether latency is considered or not will determine if delay impacts throughput.
Latency
Every electromagnetic signal has a minimum propagation time due to the speed of light. Below, where s is the distance and cm is the medium’s speed of light (about 200,000 km/s for the majority of fiber or electrical media, depending on their velocity factor), the delay cannot be decreased. This roughly translates to one extra millisecond of round-trip delay (RTT) for every 100 kilometers (62 miles) that separates the hosts.
Intermediate nodes also have additional delays. Queuing can lead to delays in packet switching networks.
Jitter
In electronics and telecommunications, jitter is the undesirable departure of an assumed periodic signal from genuine periodicity, frequently with respect to a reference clock source. Features like the frequency of succeeding pulses, the amplitude of signals, or the phase of periodic signals can all exhibit jitter. A major, and typically undesirable, component in the design of nearly all communications lines is jitter (e.g., USB, PCI-e, SATA, OC-48). It is referred to as timing jitter in clock recovery applications.
Error rate
The number of bits received during a digital transmission that have been distorted by noise, interference, distortion, or bit synchronization faults is known as the number of bit errors.
The number of bit errors divided by the total number of bits transferred during the analyzed time frame yields the bit error rate, also known as the bit error ratio (BER). A unitless performance metric known as BER is frequently given as a percentage.
The expectation value of the BER is the bit error probability, or pe. One way to think of the BER is as a rough estimate of the bit error probability. With a large number of bit mistakes and a long time gap, this approximation is accurate.
Interplay of factors
The aforementioned elements all contribute to the perceived “fastness” or usefulness of a network connection, as do user needs and perceptions. The best way to understand the relationship between throughput, latency, and user experience is as a scheduling problem over a shared network medium.
Algorithms and protocols
Throughput and latency are related concepts for some systems. Latency can also have a direct impact on throughput in TCP/IP. The throughput of a high-latency connection effectively decreases with latency due to the enormous bandwidth-delay product of these connections and the relatively limited TCP window sizes on many devices. Several methods, such as enlarging the TCP congestion window or more extreme approaches like packet merging, TCP acceleration, and forward error correction—all of which are frequently employed for high-latency satellite links—can be employed to address this.
Through TCP acceleration, TCP packets are transformed into an UDP-like stream. Because of this, both ends of the high-latency link need to support the technique being used, and the TCP acceleration software needs to provide its own procedures to guarantee the link’s dependability while accounting for the link’s latency and bandwidth.
Performance concerns like throughput and end-to-end delay are also handled in the Media Access Control (MAC) layer.
Examples of latency or throughput-dominated systems
Regarding end-user usefulness or experience, many systems can be classified as being dominated by either latency or throughput restrictions. Hard restrictions, like the speed of light, might occasionally cause special issues for these systems for which there is no workaround. Significant balance and optimization for the optimal user experience are possible with other systems.
Satellite
The route length between a telecom satellite in geosynchronous orbit and the recipient must be at least 71,000 kilometers. This denotes a minimum 473 ms latency—the time interval between a message request and its receipt. Regardless of the throughput capacity that is available, this delay can be highly evident and impact satellite phone service.
Deep space communication
Communicating with space probes and other long-range objects outside of Earth’s atmosphere makes these long-path problems worse. One such system that has to deal with these issues is the Deep Space Network that NASA has put in place. The GAO has questioned the present architecture, which is primarily latency-driven. Many approaches, including delay-tolerant networking, have been put forth to deal with the sporadic connectivity and lengthy packet delays.
Even deeper space communication
It is extremely difficult to construct radio systems that can achieve any kind of throughput at interstellar distances. In many situations, keeping the lines of communication open is a greater challenge than its duration.
Offline data transport
The majority of backup tape archive deliveries still involve vehicles because throughput is the only factor in transportation.
Conclusion to Network Performance
In conclusion, network performance is a multifaceted aspect encompassing bandwidth, throughput, latency, jitter, and error rate. The interplay of these factors significantly influences user experience. Algorithms and protocols, especially in high-latency connections, play a crucial role in managing throughput and latency. Various systems, such as satellites and deep space communication, face unique challenges driven by latency or throughput restrictions, impacting end-user utility. Ultimately, achieving optimal network performance requires a nuanced understanding of these elements and their dynamic interactions.
FAQs
- What is network performance?
- Network performance refers to the metrics that indicate how users perceive the quality of a network’s service.
- How is network performance measured?
- Network performance can be measured through metrics such as bandwidth, throughput, latency, jitter, and error rate.
- What is bandwidth and throughput?
- Bandwidth is the highest speed at which data can be transported, measured in bits per second. Throughput is the actual rate at which information is conveyed.
- What is latency, and how does it affect network performance?
- Latency is the time delay between sending and receiving data. It is influenced by signal travel time and processing speed, impacting the perceived speed of a network.
- What is jitter in the context of network performance?
- Jitter is the undesirable deviation of a periodic signal from its expected periodicity. In networking, it can affect the consistency of signal transmission.
- How is error rate measured in network performance?
- Error rate is the proportion of corrupted bits in the total delivered data. It is often expressed as the bit error rate (BER), a unitless metric frequently given as a percentage.
- How do factors like bandwidth, throughput, and latency relate to user experience?
- These factors collectively contribute to the perceived “fastness” or usefulness of a network connection, influencing user satisfaction.
- How do algorithms and protocols impact network performance?
- Algorithms and protocols play a crucial role, especially in high-latency connections, in managing throughput and latency to enhance overall network performance.
- What are some examples of systems dominated by latency or throughput restrictions?
- Systems like satellite communication, deep space communication, and offline data transport face unique challenges driven by either latency or throughput restrictions.
- How can optimal network performance be achieved?
- Achieving optimal network performance requires a nuanced understanding of bandwidth, throughput, latency, jitter, and error rate, along with the dynamic interactions of these elements. Implementing suitable algorithms and protocols is also crucial.
