Computer Networks and the Internet
This week, we learned about the Internet and how computer networks are connected. The Internet can be viewed in two ways: as billions of connected computing devices or as infrastructure that provides services to applications. Networks consist of clients and servers that send information back and forth to each other.
Two ways that information can be sent is via packet switching or circuit switching. Packet switching is when information is sent as a packet through communication links and routers or link-layered switches. The packet is sent with no resources reserved and between a shared network. If a network is congested, it is possible that a packet can be delayed, or pieces of the packet can be lost if the buffer holding the packet is full. While delivery is not guaranteed, the process is timely. Circuit switching is when packets are sent only on dedicated links. This process can be wasteful as dedicated lines become idle when not in use and cannot be used by any other connection. Packet switching is good to use when you have burst data, while circuit switching is good to use when a continuous, reliable connection is needed.
When using packet switching, it is important to note that packets can be delayed or parts of a packet can be lost. Four types of delays can occur: nodal processing delay, queuing delay, transmission delay, and propagation delay. Nodal processing can be delayed if the time required to determine where the packet is directed. Queuing can be delayed if a packet waits too long to be sent through the link. Transmission of the packet can be delayed if the packet's bits are not passed to the link fast enough. Propagation delay can occur if a package takes too long to get from the beginning of a link to a router. In addition to a delay, it is also possible that packets or pieces of a packet can be lost. This can happen if a queue is full after the packet has been sent. The part of the packet can be lost in transmission.
End-to-end throughput, the rate at which bits are transferred between the sender and receiver, is an important performance measure to consider when sending information from client to server. This measure can vary depending on the amount of traffic and the transmission rate. For example, if a link has a high transmission rate, it may be favorable for clients/servers to send information through, which can cause a bottleneck of data. To prevent this, links providing the paths for the network need to be balanced so that data flows smoothly.
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