Networking is very important in the world of computer. Networking is the activity of connecting the computers to each other to make-up the computer network. In other word is the purpose of sharing data through linking of two or more computing devices together. Networks are built with a mix of computer hardware and computer software. A computer network is a collection of computers and devices connected together via communications devices and transmission media.
There are few factors that affect the performance of computer networks. Those factors will reduce the quality of service of the network. The major factors are Latency, Packet loss, Retransmission, Throughput and Queuing delay.
Latency is the kinds of delays typically incurred in processing of network data. A low latency network connection is one that generally experiences small delay times, while a high latency connection generally suffers from long delays.
Although the peak bandwidth of a network connection is fixed according to the technology used, but the actual bandwidth which is obtained change over time and is affected by high latencies. Excessive latency creates bottlenecks that prevent data from filling the network pipe, thus decreasing effective bandwidth. The result of latency on network bandwidth can be temporary which may lasts for a few seconds or constantly depends on the source of the delays.
To measure the Network Latency tools like ping tests and trace-route are used. The measuring is done by determining the time it takes a given network packet to travel from source to destination and back, and this the so-called round-trip time. Round-trip time is not the only way to specify latency, but it is the most common.
2. Packet loss
Packet loss is the failure of one or more transmitted packets to arrive at their destination. There are various reasons for packet loss. Sometimes the signal may degrade over time. Sometimes hardware problems could originate packet loss. Networks that have too much demand and corrupted packets also might be a reason for packet loss.
If packet loss occurs, computers may try to recover that information. Once a packet is received, that computer sends a signal to the sending computer that it has been received. It will resend any packets for which it does not receive a signal if the sending computer does not receive a signal for every packet sent.
Commonly, it is not an issue to resend the packets, but sometimes there are some applications where resending packets is not possible. Resending a packet of lost information in such a case is not realistic. It also is true for voice communication applications. To some extent, it can be prevented by prioritizing the type of packets that are to be sent. Generally, there is not much the average computer user can do to avoid packet loss issues. If it is happening always on a local area network, such as in a business environment network’s IT professional may offer some relief. By making sure the hardware is in proper working state can avoid the packet lost.
It means resending of packets which have been either damaged or lost. Retransmission is basic mechanisms which used by protocols operating on a packet switched computer network to provide consistent communication. Networks are usually varying, no guarantee for no delay or no damage, no packets lost and no unordered delivery will occur. Protocols which provide reliable communication on such networks use a combination of sending acknowledgments, retransmission of missing or damaged packets and checksums to make sure the reliability.
There are several forms of acknowledgments can be used in networking protocols. Positive Acknowledgement is one of the forms of sending acknowledgement. The receiver clearly notifies the sender which packets, messages, segments were received correctly. In the mean time it absolutely informs the sender which packets were not received even though they were sent and therefore may need to be retransmitted. Positive Acknowledgment with Retransmission is a method used by TCP to confirm receipt of transmitted data. This operates by re-transmitting data at well-known period of time until the receiving host acknowledges response of the data.
Negative Acknowledgment is another form of acknowledgment. The receiver clearly notifies the sender which packets, messages, or segments were received wrongly and therefore which may need to be retransmitted.
A Selective Acknowledgment (SACK) is the form which sends receiver clearly lists which packets, messages, or segments in a stream are acknowledged where negatively or positively.
A Cumulative Acknowledgment is another form which sends the receiver acknowledges that it correctly received a packet in a stream which absolutely informs the sender that the previous packets were received correctly.
Throughput is the rate at which a computer or network sends or receives data. It is a good measure of the channel capacity of a communications link, and connections to the internet are usually rated in terms of how many bits they pass per second (bit/s). When the number of buffers that the redirector reserves for network performance is increased it increases network throughput.
5. Queuing delay
The queuing delay is the time a work waits in a queue awaiting it can be executed. It is a key component of network delay. This is the delay stuck between the point of entrance of a packet in the transmit line up to the real point of transmission of the message. This delay depends on the weight on the communication link. Queues may be caused by delays at the originating switch, intermediate switches, or the call receiver servicing switch. Queuing delay is increases if the buffer size increases. The longer the average waiting time is taken for the longer the line of packets. This is much preferable to a shorter buffer, which would result in ignored packets in turn it would result in much longer overall transmission times.