comp4 unit7d lecture slides

Introduction to Information and Computer Science

Networks

Lecture d

This material (Comp4_Unit7d) 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

IU24OC000015.

NetworksLearning 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)

2Health IT Workforce Curriculum Version 3.0/Spring 2012

Introduction to Information and Computer Science Networks

Lecture d

Wireless Communications

• Wireless devices communicate without cabling.• Signals sent via:

• Infrared light – laptop to laptop• Microwave – requires clear line of sight• Radio frequency - most common method

• Governed by IEEE 802.11 standard.• Seems to be available everywhere!

Health IT Workforce Curriculum Version 3.0/Spring 2012

3Introduction to Information and Computer Science Networks

Lecture d

Wireless – The Good, The Bad, & The Ugly

• Good:• No cables needed to connect devices to network.• Cleaner work environment without cables.• Devices can be easily moved about.• Easy for users to connect.

• Bad:• Can be slower than wired networks.• Limited signal range.

• Ugly:• Security issues.



Lecture d

How Does Wireless Function• Home wireless communication is done by radio

frequency.• Radio frequencies are mapped to channel numbers.• In North America, channels are 1-13 for 802.11 a/b/g

• Need the following for typical home setup:• Computers need wireless NICs

– Facilitates connection to a wireless router.• Network needs a wireless router

– Also known as a wireless access point (WAP).• Wireless router needs to connect to a wired device

– To get Internet access, wireless router needs wired connection to the ISP device (cable modem router).



Lecture d

Wireless Network Setup• WAP:

• SSID – name for wireless network.• Change WAP default password since globally known.• IP address and subnet mask.• Configure WPA2 and record the code/phrase created.• Cable WAP so it somehow connects to ISP device.

• Each wireless client:• SSID configured same as WAP.• IP address and subnet mask in same range as WAP.• Configure WPA2 using code/phrase from WAP.



Lecture d

Wireless Network Setup (cont’d)• Standards are backwards compatible

• 802.11g NICs work in 802.11 a/b device-controlled WLANs.

• Wireless RF channels• WAPs and clients must use same channel.• Different channels cannot communicate.• Channel numbers correspond to an RF range.• Channels 1, 6, and 11 RF do not overlap. Use one of

these!– Channel 5 uses the RF range of 2.421–2.443 GHz.– Channel 6 uses the RF range of 2.426–2.448 GHz.



Lecture d

Wireless Components Example

• The notebook is connected to the wireless access point using a PC card.

PC card (wireless NIC)

Wireless Access Point (WAP)

Network cable connection to wired network.

(Porao, 2005, CC BY-SA 3.0)



Lecture d

http://en.wikipedia.org/wiki/File:Wireless_network.jpg

Network Hardware

• Common components are: Networked devices NIC (wired and wireless) Switch Router ISP device Server Surge protector Uninterruptable Power System (UPS)



Lecture d

Network Hardware - Networked devices

• Computers / Laptops with:• Network-enabled operating system (OS).• NIC to connect to switch/router.• Cabling for wired network.



Lecture d

Network Hardware - NICs • Required for network communication

• Hardware uses OS services to communicate on network.

• Wired – requires cabling, jacks, switch/router.• Wireless – requires WAP and some wired device

to communicate with wired devices.

Vintage 10 Mbps Ethernet NIC for wired network.

(Helix84, 2005, CC BY-SA 3.0)



Lecture d

54 Mbps Wireless LAN PCI Card (802.11g).

(Wheeler, 2007, CC BY-SA 3.0)

http://en.wikipedia.org/wiki/File:Network_card.jpg

http://en.wikipedia.org/wiki/File:WLAN_PCI_Card_cleaned.png

Network Hardware – Switch • Very important network component.• Devices plug into switch to communicate with

each other.• Switch plugs into ISP device to provide Internet

access.

Image shows a 5-port Atlantis Ethernet switch.

If this switch connects to an ISP device, with five ports it could also accommodate a printer and three other devices.

One of the devices could be a WAP, which would allow wired and wireless clients to communicate with each other.



Lecture d

(Sub, 2007, PD-US)

http://en.wikipedia.org/wiki/File:Ethernet_switch_Atlantis_A02-F5P_5_ports_backend.jpg

Network Hardware - Router• Network boundary defined by IP address and

subnet mask numbers.• Router connects different IP networks so they can

communicate with each other.• Routers can be wired or wireless.• ISP devices are routers.

Image shows a Cisco Linksys WRT54GL wireless router typically found in a SOHO (small office, home office) network.

The blue Ethernet cable extending out of its rear, to the right, connects this device to the wired network



Lecture d

(Jackzor, 2008, PD-US)

http://en.wikipedia.org/wiki/File:Linksys_WRT54GL.jpg

Routed Network Example

Small Office / Home Office

(Feval, 2006, CC BY-SA 3.0)



Lecture d

Network Hardware – ISP Device• Connects SOHO and Office networks to Internet.• Can lease from ISP with Internet service.

• Sometimes available for purchase too.• Usually has one Internet port to connect to a wall port.• Usually has one switch port to connect one device using

Ethernet cable.• Can use that port to connect to a switch, which can

connect to other devices or other switches to extend network.

• All devices then share the one Internet connection.



Lecture d

ISP Device Examples• The image on the left

shows a Motorola cable modem. This router uses the ISP’s coaxial cable to provide Internet connectivity.

• The image on the right shows a wireless D-Link router/modem used as a residential DSL gateway. This router uses the ISP’s Ethernet cable to provide Internet connectivity.

(Larocomp, 2010, PD-US)



Lecture d

(Macic7, 2007, CC BY 3.0)

http://en.wikipedia.org/wiki/File:Wirelessadsl2+router.dlink.dslg684t.JPG

Network Hardware - Server• Computer with specialized OS installed.

• Windows Server 2008• Ubuntu Server• Novell Open Enterprise Server

• Creates ‘gated community’ of devices and users.• Server maintains database of objects, restricts access to authorized

devices/users, and manages them.• Can provide various functions:

Domain controller Print server DHCP server DNS server File server Certificate server NAP server



Lecture d

Network Hardware – Surge Protector

• Protects devices from spikes in power usually originating with the power company.• Some power strips are also surge protectors – need

to carefully read product information to differentiate.• Devices need to be plugged in to gain protection.• Power surge can destroy a devices circuitry.• Protection measured in Joules.

• Joules define how much electricity the surge protector can absorb without failure.

• Should consult electrician to protect hardware.Health IT Workforce Curriculum Version 3.0/Spring 2012


Lecture d

Network Hardware - UPS• Uninterruptible power supply (UPS) provides

emergency power to attached devices when power fails.

• Short battery power time (5-30 min.) depending on attached devices.• Computer and monitor – portable unit okay.• Whole building – need large (site) solution.

• Never plug laser printer into UPS.• Due to power requirements, will instantly drain

available UPS battery power.Health IT Workforce Curriculum Version 3.0/Spring 2012


Lecture d

Surge Protector & UPS Examples

(Amakuru, 2006, CC BY-SA 3.0)



Lecture d

(Cgxke, 2008, PD-US)

(Amakuru, 2006, CC BY-SA 3.0)

http://en.wikipedia.org/wiki/File:Surge_protector.jpg

http://en.wikipedia.org/wiki/File:UPSRearView.jpg

http://en.wikipedia.org/wiki/File:500kVA-UPS.jpg

NetworksSummary – Lecture d

•Describe wireless communication•List and describe network hardware



Lecture d

NetworksReferences – Lecture d

References • Wikipedia. Medical Implant Communication Service. [Internet]. 2011 Jun [cited 2011 Nov 07]. Available from:

http://en.wikipedia.org/wiki/Medical_Implant_Communication_Service. • Wikipedia. Wireless LAN. [Internet]. 2011 Jun [cited 2011 Nov 07]. Available from:

http://en.wikipedia.org/wiki/Wireless_LAN. • Wikipedia. Network switch. [Internet]. 2011 Jun [cited 2011 Nov 07]. Available from:

http://en.wikipedia.org/wiki/Network_switch. • Wikipedia. Surge protector. [Internet]. 2011 Jun [cited 2011 Nov 07]. Available from:

http://en.wikipedia.org/wiki/Surge_protector. • Wikipedia. Uninterruptible power supply. [Internet]. 2011 Jun [cited 2011 Nov 07]. Available from:

http://en.wikipedia.org/wiki/Uninterruptible_power_supply.



Lecture d

http://en.wikipedia.org/wiki/Medical_Implant_Communication_Service

http://en.wikipedia.org/wiki/Wireless_LAN

http://en.wikipedia.org/wiki/Network_switch

http://en.wikipedia.org/wiki/Surge_protector

http://en.wikipedia.org/wiki/Uninterruptible_power_supply

NetworksReferences – Lecture d

Images • Slide 8: Wireless Network Components [image on the Internet]. (Porao, 2005, CC BY-SA 3.0) [cited 2011 Nov

07]. Retrieved Jan 2012 from: http://en.wikipedia.org/wiki/File:Wireless_network.jpg. • Slide 11: Network Interface Card [image on the Internet]. (Helix84, 2005, CC BY-SA 3.0) [cited 2011 Nov 07].

Retrieved Jan 2012 from: http://en.wikipedia.org/wiki/Network_interface_card. • Slide 11: Wireless Interface Card [image on the Internet]. (Wheeler, 2007, CC BY-SA 3.0) [cited 2011 Nov 07].

Retrieved Jan 2012 from: http://en.wikipedia.org/wiki/File:WLAN_PCI_Card_cleaned.png. • Slide 12: Network Switch [image on the Internet]. (Sub, 2007, PD-US) [cited 2011 Nov 07]. Retrieved Jan 2012

from: http://en.wikipedia.org/wiki/File:Ethernet_switch_Atlantis_A02-F5P_5_ports_backend.jpg. • Slide 13: Cisco Linksys Wireless Router [image on the Internet]. c2008 [cited 2011 Nov 07]. Retrieved Jan 2012

from: http://en.wikipedia.org/wiki/File:Linksys_WRT54GL.jpg. • Slide 14: SOHO Wireless Network [image on the Internet]. (Feval, 2006, CC BY-SA 3.0) [cited 2011 Nov 07].

Retrieved Jan 2012 from: http://en.wikipedia.org/wiki/File:SPOF.png. • Slide 16: Motorola Cable Modem Router [image on the Internet]. (Larocomp, 2010, PD-US) [cited 2011 Nov 07].

Retrieved Jan 2012 from: http://en.wikipedia.org/wiki/Cable_modem. • Slide 16: D-Link Wireless Router [image on the Internet]. (Macic7, 2007, CC BY 3.0) [cited 2011 Nov 07].

Retrieved Jan 2012 from: http://en.wikipedia.org/wiki/File:Wirelessadsl2%2Brouter.dlink.dslg684t.JPG. • Slide 20: Large UPS Device [image on the Internet]. (Cgxke, 20087, PD-US) [cited 2011 Nov 07]. Retrieved Jan

2012 from: http://en.wikipedia.org/wiki/File:500kVA-UPS.jpg. • Slide 20: Small UPS Device [image on the Internet]. (Amakuru, 2006, CC BY-SA 3.0) [cited 2011 Nov 07].

Retrieved Jan 2012 from: http://en.wikipedia.org/wiki/File:UPSRearView.jpg. • Slide 20: Multi-outlet Surge Protector [image on the Internet]. (Amakuru, 2006, CC BY-SA 3.0) [cited 2011 Nov

07]. Retrieved Jan 2012 from: http://en.wikipedia.org/wiki/File:Surge_protector.jpg.



Lecture d

http://en.wikipedia.org/wiki/File:Wireless_network.jpg

http://en.wikipedia.org/wiki/Network_interface_card

comp4 unit7d lecture slides

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