1. Introduction to Information and Computer Science
Welcome to the Introduction to Information and Computer Science, Networks. This is Lecture (a).
The component, Introduction to Information and Computer Science, provides a basic overview of computer architecture; data organization, representation and structure; structure of programming languages; networking and data communication. It also includes basic terminology of computing.
Networks
Lecture a
This material (Comp4_Unit7a) was developed by Oregon Health and Science University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information Technology under Award Number IU24OC

2. Networks Learning Objectives
List and describe the various types of network communications and network addressing (Lecture a and b)
List and define the different types of networks (Lecture c)
Describe different network topologies (Lecture c)
List and describe different network standards and protocols (Lecture c and e)
Describe wireless communication (Lecture d)
List and describe network hardware (Lecture d)
The objectives of Networks are to:
List and describe the various types of network communications and network addressing
List and define the different types of networks
Describe different network topologies
List and describe different network standards and protocols
Describe wireless communication
List and describe network hardware
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Introduction to Information and Computer Science Networks Lecture a

3. Introduction to Information and Computer Science Networks Lecture a
What is a Network?
According to Wikipedia, a network is:
“…a collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users.” (Wikipedia, 2011)
In English please…
A network is made up of computers, printers, other devices, and some sort of media (cabling, wireless) that allows all of these devices to communicate with each other.
This lecture will discuss network communications and network addressing and covered network types, benefits, description of connections, and source providers.
It is appropriate to begin this discussion with the definition of a network. According to Wikipedia, a network is "A collection of computers and devices connected by communications channels that facilitates communication among users. It allows users to share resources with other users."
Note that in “English,” a network is comprised of computers, printers, and other devices, along with some sort of media. The term media means cabling and/or the ability to communicate wirelessly, which allows all of the devices to communicate with each other.
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4. Modern Network Example
A site-to-site network with support for remote users.
To visualize what a moderate network would look like; examine the figure on the screen where two regional offices are connecting to the head office. Remote users, those working at home—or traveling employees—also need to connect to the head office.
Note that they are connecting through the Internet and that the Internet service provider or ISP [I-S-P] devices shown in the figure are interconnecting all of the sites. Additionally, the routers at the regional offices are connecting to a router at the head office.
Ludovic.ferre, 2010, CC BY-SA 3.0)
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5. Introduction to Information and Computer Science Networks Lecture a
Why Networks?
Share hardware –
Printer, scanner, data storage devices.
Share software –
Software installed on a server to reduce cost.
Share files –
Images, spreadsheets, documents.
Communicate –
, network phones, live chat, instant messaging.
Networks are a recent innovation in homes and workplaces. In the “old” days, perhaps one hundred people would have to use one printer. There were no servers that could share software, reducing the cost of business. No one was sharing files such as pictures, music, spreadsheets, and documents.
And imagine life without . Networks facilitate use. Network phones (phones that use IP addressing), live chat, instant messaging, and all of the things that are taken for granted today did not exist just a generation ago. All of this is possible because of a networking infrastructure.
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6. Networks Decrease Cost
Printed documentation moved to a Web server.
No longer need to update physically. Can update Web page and notify users of changes.
done electronically and replaces paper documents.
Easier to keep device software current.
No need to physically visit each device to manage it or upgrade software.
It is important to point out that networks decrease costs for business, individuals, and government. For example, what was once printed documentation can now be located digitally on a Web server. This means that users no longer need to update documentation physically; instead, the user updates a Webpage and then notifies users of the changes.
In the past, technical support teams printed documentation and kept copies at their desks so that they could answer questions that came in from customers. If there were a change to the documentation, someone had to reprint and distribute the documentation to perhaps 200 technical support agents. Web servers have eliminated that effort and cost.
Networking has also brought us as a form of electronic paperwork, eliminating the need for interoffice paper memos and mailing costs, for example.
Finally, it is easier to keep device software current. Network administrators no longer need to physically visit each device to manage it or to upgrade its software. Through networking, administrators can locate a device, connect to that device, and then make changes to it.
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7. Networks Serve Customers
Documentation can be posted online in Web pages and kept current by changing one document.
Customers can chat or with customer service reps.
Customer service reps have access to a common network database containing solutions to common customer requests or issues.
In addition, networks serve customers. For example, documentation can be posted and maintained on online Web pages. Customers can be notified of changes by . Either way, customers will always have the latest information when they visit those specific Web pages.
Customers can chat or with customer service representatives. Today it is common to find live chat services with vendors where customers can have their questions answered in real time, as opposed to using that may have taken a vendor several days to respond to.
Customer service reps also have access to a common network database containing solutions to common customer requests or issues. In the past, support representatives might have needed to have printed documentation at their desks when providing tech support to customers. Since this method of providing support is not cost-effective, it is rare to find reps using printed material anymore.
Solutions to customer issues can be stored in a database to record whether or not a particular solution was successful. If a solution is unsuccessful and does not solve an associated problem, it can easily be replaced in the database with a solution that is successful, which helps companies improve customer satisfaction.
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8. Networks Serve Customers (continued)
Hospitals can store all patient data in one common network database, improving quality of care.
Medical staff and patients can access electronic medical records stored in a network database.
In addition, hospitals can store all patient data in one common network database, which improves the quality of care. Medical staff and patients can access electronic medical records stored in a network database as well. In some cases, a medical staff person, for example, a nurse, might walk into a room. When the nurse walks into the room, all of the information that the nurse needs to see related to that patient can be transferred from his or her badge onto a screen in that room.
In addition, the patient can see the name of the nurse on another screen. Again, all of this is accomplished by a network.
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9. How Devices Connect to a Network
Wired or wireless connections.
Network may be connected to the Internet.
An Internet connection requires the use of an ISP.
An intranet connection does not connect a device to the Internet.
However, it may connect various offices together, regardless of their location (Chicago to Portland) and not provide Internet access.
Devices such as scanners, printers, and computers connect to a network using a wired and/or wireless connection. The network to which those devices are connected may or may not be connected to the Internet. An Internet connection requires the use of an ISP. For example, a home user who wants access to the Internet needs to purchase a service plan from an ISP in order to connect to the Internet.
On the other hand, an intranet [in-truh-net] connection does not connect a device to the Internet. For example, the network at an organization or company is an example of an intranet. If employees need to have access to a Web server at Google, for example, then the company would need an Internet connection.
An intranet, however, can connect various offices together regardless of their location, without providing Internet access.
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10. Wired vs. Wireless Networks
Wired connections:
Require NIC, copper cables, switch, router.
Home routers also contain switch ports.
Wireless connections:
Require wireless NIC, WAP, switch, router.
Most routers contain a few switch ports.
Fiber connections:
Require fiber NIC, fiber optic cables, switch, router.
Most routers and switches do NOT contain fiber ports and they can be costly to purchase.
Wired connections require that devices have a NIC [nihk] installed. A NIC is a network interface card; it will be either wireless or wired. The wired NIC must provide a port to plug in the network cable.
Networks also need copper cabling (category six cable for example), a switch — which allows devices within a home office to communicate with one another; and a router. A router allows a home to communicate via the Internet. Cable modem routers are an example of a modern router.
Home routers also contain switch ports, and in these cases, the router acts as both a switch and a router. To get to the Internet, users might plug their computer into a switch port on the router and then connect the router to the cable that comes from the ISP.
To make wireless connections, devices must have a wireless NIC and a wireless access point or WAP [wap]. A WAP consists of a wireless router, a switch, and perhaps some other type of a router. Again, most wireless routers contain a few switch ports.
Users can also connect to a network using fiber-optic cabling, which contains at its middle a glass core thinner than human hair. This glass core is called a “fiber.” Fiber-optic technology transmits pulses of light through the glass core. To use fiber to connect devices requires a purchase and installation of a fiber NIC, fiber-optic cables, a switch that provides fiber ports, and a router that provides fiber ports.
Most routers and switches do not contain fiber ports; these ports can substantially increase the cost of these devices. Fiber-optic cabling works best when cable must run long distances, when cable must run through areas where it might encounter electromagnetic interference, and where users need high bandwidth.
For example, fiber-optic cable is not disturbed by high levels of nearby electricity like copper wire. Further, one fiber can replace thousands of copper wires and can extend well over 50 miles in length!
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11. Introduction to Information and Computer Science Networks Lecture a
It’s All About Speed
Networks measure speed using the terms bandwidth and throughput.
Bandwidth is the highest number of bits that can be sent at any one time.
Throughput is the amount of bandwidth you can use for actual network communications.
Example:
Bandwidth on your cabled network is 100 Mbps.
Because of physical limitations and other required network traffic, throughput is usually approx. 70 Mbps.
Networks measure speed with the terms “bandwidth” and “throughput.”
Bandwidth is the highest number of bits that can be sent at any one time. Throughput, on the other hand, is the amount of bandwidth that is available for actual network communications. For example, the bandwidth of a home network might be 100 megabits per second using typical network cabling.
Because of physical limitations in the copper and other required network traffic and communication, the throughput is usually only about 70 megabits per second. Therefore, this network would lose about a third of its bandwidth because of what is referred to as communication overhead.
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12. It’s All About Speed (continued)
Speed is influenced by the network media:
Copper wire speed is commonly 100/1,000 Mbps.
Wireless speed is commonly 54 Mbps.
The ‘Draft N’ standard offers approx. 200 Mbps speed!
Fiber optic cable offers the same speeds as copper wiring but can travel longer distances.
The speed at which bits are passed from source to destination (for example from a user’s computer to another computer) is influenced by the network media. Copper wire speed is commonly 100 or 1,000 megabits per second. Note that 1,000 megabits per second is one gigabit per second bandwidth.
Wireless speed, on the other hand is typically much slower. Currently, wireless speed runs at approximately 54 megabits per second—although the Draft “N” wireless standard offers approximately 200 megabits per second speed.
Fiber-optic cable offers the same speeds as copper wiring but can travel much longer distances. In the images shown on the screen in the bottom-left corner, there are two fiber-optic cable connectors displayed. On the left, within that image, there are fiber LC connectors. On the right side, within that image, are what is referred to as SC connectors. The meaning of the fiber connector acronyms is not important at this point.
The fiber connector ends each plug into a fiber port. Notice the white caps found at the very end of the LC and SC connectors. These cover up the ferrules [fer-uhlz] or the very end of the fiber optic connector where there is a plastic or glass solid core. Laser light is shined into the core and the photons are passed from end to end.
The image on the right depicts a copper wire with an RJ-45 jack. This copper wire has eight individual wires, each covered with a sheathing to protect each individual wire. Look at the RJ-45 jack. At its very end are a number of colored wires. These are the eight copper wires through which electronic impulses pass.
Networking specialists can learn how to create these types of cables.
Left: LC/PC connectors.
Right: SC/PC connectors.
All four connectors have white caps covering the ferrules.
Copper wiring with RJ-45 jack at end.
(Poil, 2005, CC BY-SA 3.0)
(Dflock, 2004, PD-US)
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Introduction to Information and Computer Science Networks Lecture a

13. Service Providers and You
Internet Access Providers connect users to the Internet.
Access to the Internet revolves around the use of ISPs.
ISPs are organized as local, regional, and national providers.
ISPs connect users to the Internet. Home users probably have a contract with an ISP that allows connection to the Internet using their services.
In fact, access to the Internet globally revolves around the use of ISPs. As depicted in the figure shown on the slide, ISPs are organized as local, regional, and national providers and in some cases, even international providers.
A tier 1 ISP is a large national or international provider. A tier 2, or regional, ISP connects a local ISP to tier 1 ISPs. Local ISPs are referred to as tier 3 ISPs.
(Ludovic.ferre, 2010, CC BY-SA 3.0)
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14. Connecting to the Internet
Devices commonly connect to the Internet via dialup, broadband, Wi-Fi, satellite, and 3G.
Dialup – copper phone lines to connect to an ISP’s modem. Limited to a speed of 56 Kbps.
The slowest connection type!
Broadband – higher quality copper phone lines, coaxial cable, or fiber optic connection type.
Faster than dialup and in the approximate range of 768 Kbps and higher.
Devices commonly connect to the Internet via dial-up, broadband, Wi-Fi, satellite, or 3G or 4G connections.
Dial-up connections use copper phone lines to connect to an ISP's modem. This speed —or bandwidth—is limited to 56 kilobits per second. This is the slowest and most frustrating connection type.
Broadband connections have higher quality copper phone lines, perhaps coaxial cable, also known as coax cable, and perhaps fiber optic connection types. Broadband is faster than dial-up, and it runs in the approximate speed range of 768 kilobits per second or higher.
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15. Connecting to the Internet (continued)
Wi-Fi – wireless (radio frequency) connection type.
Wi-Fi refers to the IEEE standard governing wireless technologies.
Typically used to connect laptops to WAPs. The WAP is connected to the wired network to gain access to the Internet.
Also used extensively by hotels and airports.
Wireless speeds range from 1 Mbps to 200+ Mbps, depending on a variety of factors.
Wi-Fi is a wireless connection type governed by IEEE [eye-triple-E] [eight-oh-two-dot-one-one] standards. The IEEE is the Institute of Electrical and Electronic Engineers, a global standards organization. This organization creates and publishes standards that relate to the various types of network connections. The IEEE is heavily involved in many networking and electronic standards.
Wi-Fi is typically used to connect laptops to a WAP, which in turn is then connected to the wired network, usually through a switch or through some type of an ISP router.
Wi-Fi is used frequently in hotels and airports. In fact, in most hotels, users are able to gain access to the Internet using some type of a Wi-Fi connection. Many small regional airports provide free Wi-Fi access to passengers waiting in terminals, whereas larger airports view this as a revenue opportunity.
Wireless speeds can range anywhere from 1 megabit per second, which is extremely slow, to well over 200 megabits per second. Wireless networking equipment functions in one or more wireless standards such as a [eight-oh-two-dot-eleven-ay]; b [eight-oh-two-dot-eleven-bee]; g [eight-oh-two-dot-eleven-gee]; or n [eight-oh-two-dot-eleven-en]. Each wireless standard specifies, among other things, the maximum theoretical bandwidth at which it operates.
If the standard is b, for example, then bandwidth most likely is somewhere around 54 megabits per second,
depending on the laptop’s and/or the wireless device's proximity to the WAP. The farther away that a user gets from a WAP, the lower the network speed or bandwidth will be. If the connection to a WAP is at 1 megabit per second, the user is probably too far away and needs to move closer.
If a NIC is an b or an g NIC, then the user is most likely connecting at approximately 50 megabits per second., which is a decent wireless connection that indicates good proximity to the access point.
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16. Connecting to the Internet (continued)
Satellite – Connection to a ground satellite dish (antennae) and the satellite relays signals to a satellite orbiting the earth. Then the orbiting satellite relays the signal to another ground satellite dish.
Can be somewhat slow because of the time it takes to make a round trip. The loss of speed is known as “latency.”
3G – The 3rd Generation of standards governing mobile telecommunications.
Speed ranges from 2 Mbps – 5 Mbps, depending on plan and location.
Many connect to the Internet and even receive television signals via satellite. With a satellite connection, the home or office device makes a connection to a ground satellite dish, and then the satellite dish sends the signal to a satellite that is orbiting the earth. The orbiting satellite then relays the signal to another ground satellite dish and so on.
This can be somewhat of a slow connection because of the time it takes to make a roundtrip. The loss of speed introduced in this type of communication is referred to as latency.
The third and fourth generation of standards that govern mobile communications are known as 3G and 4G, with speeds ranging from 2 to 100 megabits per second, depending on the plan, cost, and location. Smart phones and tablet devices use 3G and 4G technologies to provide Internet access to devices that subscribe to their plan.
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17. Introduction to Information and Computer Science Networks Lecture a
Leasing an IP Address
ISPs lease IP addresses to subscribers.
Your private (home or business) network usually utilizes private IP addressing.
The ISP typically leases your location one public IP address.
The ISPs equipment is provided with a public IP address to connect to the ISPs public network.
The ISPs equipment is also provided with a private IP address to connect to your private network.
ISPs lease public Internet protocol, or IP, addresses to subscribers. Homes or business networks usually use private IP addressing.
The ISP typically leases each location one public IP address. The ISP's equipment is provided with a public IP address to connect to the ISP's public network. The ISP also provides equipment with a private IP address so that it can connect to the home or business network.
An IP address is generally defined as public or private.
Private IP addresses have no “real world” meaning and are indeed invalid outside of their network. For example, an individual may have three computers and a printer as part of a home or small office network. All of these devices are configured with private IP addresses. The devices are configured by manually assigning the address to the device or by dynamically receiving the address from a router.
A cable modem router has both a public and a private IP address. A private IP address is used to communicate with home computers and printers. All of these devices are configured with private IP addresses. Private IP addressing is used on home networks and office intranets.
An example of a private IP address that might be seen on a home network is [one ninety two dot one sixty eight dot ten dot one] through and including [one ninety two dot one sixty eight dot ten dot two fifty four]. This is one example of a private IP public address range.
The public IP address, on the other hand, is used to communicate with devices that are on the Internet. On the Internet, all devices possess and are assigned public IP addresses.
An example of a public IP address is There are literally millions of public IP addresses.
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18. Leasing a Dynamic IP Address
The ISPs equipment is able to translate addressing between the private and public networks.
ISPs generally provide you with an IP address that may change from day to day.
This is a typical leased, dynamic IP address and is included in the monthly fee.
Since an ISP's equipment—in this case, a cable modem router—is programmed with or possesses both a public and private IP address, the ISP's equipment must be able to translate addressing between the private and public networks.
ISPs generally provide a public IP address that may change from day to day; this is known as a dynamic IP address.
Most home IP addresses are dynamic IP addresses. In other words, rebooting an ISP's equipment may result in a different public IP address. This really is not important unless a user needs to possess an IP address that never changes, also known as a static IP address.
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19. Leasing a Static IP Address
ISPs can also lease an IP address for the duration of the contract.
The static IP address will not change.
Most Web sites use static IP addresses so that their domain name will be reliably mapped to one IP address.
ISPs charge more each month for static IP address. The charge ranges from $5 to $100, depending on provider.
If a static IP address that never changes is necessary, an ISP can lease such an address for the duration of the contract. This is known as a static IP address.
By definition, a static IP address will not change. Indeed, Internet Websites use static IP addresses so that their domain names are reliably mapped to one public IP address.
ISPs charge more each month for static IP addresses. The charge ranges from $5 to over $100 per month, depending on service provider.
ISPs are glad to lease one or more static IP addresses to customers because they can charge extra for this service.
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20. Networks Summary – Lecture a
List and describe the various types of network communications and network addressing
defined what a network is and described various types of network communications, connection types and their speeds. Different forms of network addressing were also discussed, including static and dynamic IP addresses.
This concludes Lecture (a) of Networks. In summary, this lecture addressed network communications and network addressing and covered network types, benefits, description of connections, and source providers.
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21. Networks References – Lecture a
Wikipedia. [Internet]. Available from: Accessed 2011.
References slide. No audio.
Images
Slide 4: Site-to-site Network Topology [image on the Internet]. c2010 [cited 2011 Nov 07]. Retrieved Jan from:
Slide 12: Fiber Optic Connectors [image on the Internet]. Poil (c2005) [cited 2010) Nov 07]. Retrieved Jan from:
Slide 12: RJ-45 Jack Connector [image on the Internet]. Dflock (2004) [cited 2011 Nov 07]. Retrieved Jan from:
Slide 13: Tier 1 and 2 ISP Interconnections [image on the Internet]. Ludovic.ferre (2010 ) [cited 2011 Nov 07]. Retrieved Jan from:
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