Networks. Name that topology! Tree Name that topology! Ring

Networks

Name that topology!

Topologies, such as the Ring Topology, can have redundancy built in so that if one node fails data can

travel an alternate route to the destination

Name that topology!

What does MAN stand for?

Metropolitan Area Network

What does NAN stand for?

Neighborhood Area Network

What does LAN stand for?

Local Area Network

What does WAN stand for?

Wide Area Network

What does PAN stand for?

Personal Area Network

Chapter 5: LANs and WLANs 13

Network Links A communications channel, or link, is a physical path or

frequency for signal transmissions

Bandwidth is the transmission capacity of a communications channel– Broadband– Narrowband

Communications Protocols A packet is a “parcel” of

data that is sent across a computer network– Circuit-switching

technology vs. packet switching technology

Circuit Switching• Dedicated communication path between two nodes

• Inefficient• Path capacity dedicated for duration of connection

• example: telephone system

Packet Switching• efficient

• Single node to node link can be shared by many packets over time

• example: internet

Communications Protocols Rules for efficiently transmitting data from one network node

to another– Divide messages into packets– Affix addresses to packets– Initiate transmission– Regulate flow of data– Check for transmission errors– Acknowledge receipt of transmitted data

Communications Protocols Every packet that travels over a network includes the

address of its destination device

A MAC address is a unique number assigned to a network interface card when it is manufactured

An IP address is a series of numbers used to identify a network device

IP addresses can also be obtained through DHCP

Stands for Dynamic Host Configuration Protocol

It is an auto-configuration protocol used on IP networks. Computers that are connected to IP networks must be

configured before they can communicate with other computers on the network. DHCP allows a computer to be configured automatically, eliminating the need for intervention by a

network administrator. It also provides a central database for keeping track of computers that have been connected to the

network. This prevents two computers from accidentally being configured with the same IP address

Wired Network Basics A wired network uses cables to connect network devices

Wired networks are fast, secure, and simple to configure

Devices tethered to cables have limited mobility

Ethernet Simultaneously broadcasts data packets to all network

devices– IEEE 802.3– CSMA/CD protocol

Vary in speed from 10Mbps to 100Gbps

Ethernet

• is the most widespread wired LAN technology

Ethernet

On an Ethernet, data travels on a first-come, first-served basis. If two workstations attempt to send data at the same time, a collision occurs.That data must be resent.

5 Ethernet Equipment

Ethernet Equipment Ethernet adapter (designed to support the Ethernet

protocols) Network hub Network switch Network router RJ45 connector

Hubs, Switches, & Routers

• Hub: basic networking component used to connect computers to form a LAN– a data packet coming from one port is sent to all

other ports– basically organizes your cables and relays data

signals to all computers on the LAN

• Switch: networking device that controls the flow of data by using the MAC address that is placed on each data packet– Switches divide networks into Virtual LANS (VLAN)– becoming very popular on both small and large

networks

• Router: utilize a combination of hardware/software to actually route data from source to destination– utilizes IP addresses– divides large networks into logical segments

called subnets

5 Ethernet Setup

Most routers are configured using a browser. You shouldchange the network administrator password, then verify that DHCP is enabled

Wireless Basics A wireless network transports data from one device to

another without cables or wires

Slower than wired networks

Security concerns

Bluetooth Bluetooth is a short-range, wireless network technology

designed to make its own connections between electronic devices, without wires, cables, or any direct action from a user

Bluetooth

Key Features- Robustness- Low power consumption- Low cost

Bluetooth2010 Bluetooth Innovation World Cup Winner

Pervasive Computing Group at Imperial College London, Great Britain, proposed a small sensor worn on a person's ear that's able to measure balance, body posture, activity level, and heart rate, and then transmit that information wirelessly to a computer or other device where it could be viewed by the patient's health care provider. Because the ear sensor would have to be very small and light, it would need to be low power. This is possible if the sensor is designed using Bluetooth low energy technology.

Excerpt from http://www.bluetooth.com/Pages/IWC-2010-finalists.aspx

Bluetooth

Biju Thomas of the United States proposed an impact sensor capable of providing detailed measurements of shocks in sports accidents, such as a helmet that tells you how hard you hit your head when you fell while skiing. The severity of impact could be measured and transmitted to a mobile phone using Bluetooth low energy technology. This could help detect head injuries that seem minor, but turn out to be much more severe than a person realizes.

Such impacts could be detected immediately and trigger an alarm message sent to a mobile phone. It could even help people who are knocked unconscious, by automatically dialing a pre-programmed emergency number and delivering a pre-recorded message that includes the location of the injured person. A person would have 30 seconds to turn off the alarm and prevent the emergency call from being made.

Bluetooth

Christopher Allen of the United States proposed a barbecue that could be controlled by aBluetooth enabled remote control. Allen's "iGrill" application would send information from your grill to your Apple iPhone, iPad or iPod Touch over a relatively long-range using Bluetoothtechnology. So you could relax with your guests while checking the status of your grilling food on your handheld device.

Wi-Fi Equipment If your computer is not pre-equipped with wireless circuitry,

you can purchase and install a Wi-Fi card

Sharing Files If you use Windows, it

automatically detects available LANs any time you turn on a workstation

To connect to a shared resource, you might be asked for a user ID and password

Troubleshooting Network problems can stem from a variety of sources

– Cables– Signal strength– Security– Interference– Network devices– Settings

Security

Wi-Fi Security Wireless networks are much more susceptible to

unauthorized access and use than wired networks

LAN jacking, or war driving, is the practice of intercepting wireless signals by cruising through an area

Wi-Fi Security Wireless encryption scrambles data transmitted between

wireless devices and then unscrambles the data only on devices that have a valid encryption key– WEP (Wired Equivalent Privacy)– WPA (Wi-Fi Protected Access)– WPA2– PSK

Activate encryption by using a wireless network key

Encryption Encryption transforms a message so that its contents are

hidden from unauthorized readers– Plaintext has not yet been encrypted

Decryption is the opposite of encryption– Cryptographic algorithm– Cryptographic key

Encryption Weak vs. strong encryption

AES (Advanced Encryption Standard)– standard adopted by the U.S. government

Encryption methods can be broken by the use of expensive, specialized, code-breaking computers– Brute-force method

Encryption Public key encryption (PKE) eliminates key-distribution

problem, by using one key to encrypt a message and another key to decrypt the message

PKE (Public Key Encryption)

• You can think of it as a locked front door to a building, and the door has a mail slot– Mail slot is exposed and accessible to the public;

its location (street address) is like the public key– Anyone knowing the address can go to the door

and drop a message through the slot– Only the person possessing the matching private

key (owner of the building) can open the door and read the message

War Driving

• the act of searching for wireless networks by a person in a moving vehicle using a portable computer or PDA

Story on war driving: http://www.fbi.gov/news/stories/2004/november/war_spammer111004

You may have seen HTTPS at the beginning of the URL while doing online shopping, banking, etc.

HTTPS stands for Hypertext Transfer Protocol Secure

It utilizes the SSL/TLS protocol to provide encrypted communication

and secure identification of a network web server

What does VPN stand for?

• Virtual Private Network

What does ISP stand for?

• Internet Service Provider

Networks. Name that topology! Tree Name that topology! Ring

Documents

Physical Topology Logical Topology Authentication Licensing

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