Networking Basics

1
Networking Basics

• Lesson 4

2
Objectives

• Explain why standards were developed for LANs.
• Give several examples of Ethernet architectures.
• List the features of a token ring network.
• Tell how a wireless LAN functions.
• Provide guidelines for designing a network.

3
IEEE Standards

• Many types of components in networks
• In late 1970 there were no standards
• Many proprietary techniques existed that could
  not communicate
• Standards were called for and solved the problem.

4
IEEE

• Institute of Electrical and Electronic Engineers
  (IEEE)
• Started standard in the early 80s
• Work was called project 802 (February of 80)
• Broken down into categories, .1, .2. .14
• 802 LANS make up 95 percent of networks

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Dominate IEEE standards

• Ethernet 802.3
• Token Ring 802.5
• Wireless 802.11

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Ethernet 802.3

• Originally developed by xerox in 1972
• IEEE based ethernet on xerox work
• Xerox turned 4 patents over to IEEE

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Ethernet

• Most popular LAN architecture today
• easy to install
• least expensive
• Packet Switched network

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Frame

• Transmissions are broken into frames
• Preamble
• Destination address
• Source address
• Type
• Data
• CRC

9
Ethernet

• Contention Channel Access Method
• Devices waste time waiting for channel to clear
• More devices slower access
• 10 mbps may be actually closer to 4 mbps

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Ethernet

• Maximum speed-Transmission Mode Segment
  length/Media Type
• 10Base-T
• 10 mbps Baseband twisted pair

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10 mbps Ethernet

• 10Base5
• 10 mbps
• Baseband
• Length 5 100 meters
• Used thick ethernet cable
• first ethernet used

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10 mbps Ethernet

• 10Base-FL
• fiber
• Still in use
• 10Base2
• 10Base-T

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10 mbps Ethernet

• 10Base2
• Cheapernet Thinnet
• Bus topology uses CMSA/CD
• Thin coax cable BNC connectors
• Each segment 200 meters in length
• actually 185 (607 feet)
• 5-4-3 rule
• Connect segments using repeaters

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10Base2
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10 mbps Ethernet

• 10Base-T
• 10 mbps CSMA/CD 1024 devices
• Star-wired bus topology
• Unshielded twisted pair
• Hub send signal to all devices
• Patch panels see page 100 and 101
• Widely used, replaces 10base2
• still widely exists, small number new
  installations

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10Base-T
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100 mbps Ethernet

• 10 mbps quickly became to slow
• More bandwidth, gets used up
• Mid 90s IEEE added 100 mbps standards
• Switching also helped eliminate a lot of Ethernet
  problems

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100 mbps Ethernet

• 100Base-T (Fast Ethernet)
• Approved 1995
• 100Base-T4 cat 3 or higher (uses all 4 pairs of
  wires)
• 100Base-TX cat 5 or higher
• 100Base-FX fiber optic

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100 mbps Ethernet

• 100Base-T
• similar to 10BaseT in many ways
• Used new 100 mbps nics and hubs
• See table page 103

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Switched Ethernet

• All packets sent to all devices on network,
  standard Ethernet
• Switches are intelligent hubs that only sends
  packet out correct port
• Uses table in memory, learns network
• Increases bandwidth, decreases collisions

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Switched Ethernet
22
100VG-AnyLAN

• Competing standard to 100Base-T
• Replaces CSMA/CD with demand priority
• Can be installed on voice grade twisted pair
• See page 106

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1000 mbps Ethernet

• Finalized on 1999
• 1000Base-T
• Cat 5 or higher (125 mhz)
• recommend 5e or 6 (250 mhz)
• 2 techniques to increase speed
• uses all 4 pairs
• sends 2 bits in time that 100Base-T sends .8

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10000 mbps Ethernet

• 10G Ethernet (10GbE)
• only fiber optic
• approved June 2002
• used for SANS
• medical imagining
• high speed back-ups

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Token Ring

• 802.5 specifications for Token Ring
• Developed by IBM standardized by IEEE
• 16mbps
• wired like star but functions like ring
• MAU center ring Multistation Access Unit
• MAU Ring Out (RO)
• MAU Ring In (RI)

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Token Ring

• Uses Token Passing
• Receives token from Nearest Active Upstream
  Neighbor (NAUN)
• Forwards token to Nearest Downstream Neighbor
  (NADN)
• See diagram page 109
• Self diagnosing
• No collisions
• See table page 110
• Deterministic but costly

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Wireless LAN

• 1990 IEEE developed 802.11 2 mbps standard
• 1999 802.11b 11 mbps (Wi-Fi)
• 802.11a 108 mbps (Wi-Fi5)
• 802.11g 54 mbps
• Need wireless NICs and access points no wires
  necessary

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Wireless LAN

• AP access point
• contains radio transceiver
• connects to network via RJ45 connector
• devices with wireless nics transmits to AP
• range about 115 meters but affected by building
• need site survey

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Wireless LAN

• 802.11b uses CSMA/CA
• Uses demand priority
• Request to Send
• Clear to Send
• RTS/CTS
• Less secure
• See table page 113

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Network Design

• Switches are configured in Heirarchy
• see table top page 114
• cant configure in a loop
• Smaller segments reduce traffic
• Core switches connect switches
• Workgroup switches connect machines (may use hub
  to reduce cost)

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VLANs

• Virtual LANS
• Can group like users into their own Virtual LAN
• only uses in the VLAN see their own traffic
• helps with traffic
• helps with security

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Quick Quiz

• 1. The _____ was responsible for developing
  computer network architecture standards.
• 2. The portion of an Ethernet packet that does
  not include the header is called the _____.
• 3. The _____ is a number that is computed by the
  sending device based on the contents of the
  packet.
• 4. _____ is a version of Ethernet that used to be
  very popular and was called Cheapernet and
  Thinnet.
• 5. Segments on a 10Base2 network are connected
  together through a device known as a(n) _____.

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Homework

• Critical Thinking page 119