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ComputerNetwork Engineering

  1. Scalability


Scalabilityis the tenderness of a system to accommodate more computing devicesand be able to comfortably manage that expansion.

Importanceof scalability as a network design goal:

Anetwork is a collection of computing devices that are able tocommunicate with each other and exchange data along data connectionscalled network links. These links could be network cables or wirelessmedia. This means that a network could be composed of even up to twocomputing devices exchanging data to millions. This therefore callsfor a network setup that is able to handle the growth, that is, ascalable network. If the network is not well developed andconfigured, then scalability will be chaotic. A network that is notscalable cannot be maintained, every networking expert shouldconsider developing a scalable network because it provides moreservice as it can be accessed and utilized by multiple devicessimultaneously. However a scalability is a challenging network designfeature, it poses a number of challenges implementing it, first, thecost of implementing a scalable network is high and the amount ofspace required is large (Chapter 1. Introduction to Network Design).

  1. Uptime and Downtime

Downtimein hours per week

Downtime=100%-( uptime) %


Hoursper week=24*7=168 hours.

Downtime=0.2%*168=0.336hours per week

Downtimein minutes per day

Fromabove, downtime=0.2%

Minutesper day=60*24=1440 minute

Downtimein minutes per day=0.2%*1440=2.88 minutes per day

Downtimein seconds per minute

Fromabove, downtime=0.2%

Secondsper minute=60

Downtimein seconds per minute=60*0.2%=0.12

  1. Downloading a 1 MB image

Gbpsstands for billions of bits per second.

MBaccording to the International Electrotechnical Commission (IEC)stands for 1,000,000 bytes.

Eachbyte equals 8 bits

Therefore1 MB will equal to 1,000,000*8=8,000,000bits.

Foran image to load, then its size must have been loaded fully, theloading time will be:


Whichevaluates to 0.008 seconds

Typesof overheads/delays:

  1. Network connection type

Wolverhamptoncity is located in the United Kingdom while California is a city inthe USA. These geographical differences hint that the networkconnection is a wireless one. Wireless networks transmit data at alower bandwidth as compared to cable connected networks.

  1. Latencies

Communicationlatencies such as a high server downtime would greatly impact dataretrieval from the server. Due to the distributed nature of networks,there could occur a bottleneck when trying to access a specificresource concurrently, this will also slow down the image retrievalprocess (Bandwidth, Packets Per Second, and Other Network PerformanceMetrics).

  1. Server configuration

Thisfactor can be viewed in terms of

  1. Connections per second

Dueto the distributed nature of networks, the number of connections theserver was configured to accept will determine how fast a resourcecan be obtained.

  1. Maximum Concurrent Connections.

Dueto the distributed nature of networks, a specific resource may beaccessed simultaneously by several computing devices the number ofconcurrent connections allowed by the server will influence access toa resource (Bandwidth, Packets Per Second, and Other NetworkPerformance Metrics).

  1. Transactions per Second.

Atransaction is an activity or action that must be performed tocompletion, in networking, it focuses on the rate at which a datapacket is processed or even how quick a connection to the server isestablished (Bandwidth, Packets Per Second, and Other NetworkPerformance Metrics).

  1. Packet forwarding rate

Datais always transmitted in packets packets are of different sizes andcan be set by the network administrator. Assuming data transmissionover an a single node that has no collisions when the packets are ofsmallest size, the frames that will be transmitted per second wouldbe many as opposed to data transmitted over a single node with nocollisions when the packet sizes are largest (Bandwidth, Packets PerSecond, and Other Network Performance Metrics).


Chapter1. Introduction to Network Design. Retrieved 7th Dec, 2015, from

Bandwidth,Packets Per Second, and Other Network Performance Metrics. Retrieved7th Dec, 2015, from


Retrieved7th Dec, 2015, from

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