IST 201
Chapter 5
LAN Technologies
• Ethernet – most widely used technology in LANS
• In 1970, developed and implemented by:
• Digital
• Intel
• Xerox
• IEEE 802.3 standard is based on the DIX
specification.
Ethernet Specifications
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802.3 – Ethernet
802.3u – FastEthernet
802.3z – Gigabit Ethernet (Fiber)
802.3ab – Gigabit Ethernet (UTP)
802.3ae – 10 Gigabit Ethernet
• Layer 1 specification
Media
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Carries flow of information through a LAN
Operates at Layer 1
Cat 5 UTP – primary media in Ethernet networks
NIC Ports
• RJ45
• AUI – attachment unit interface
• 15 pin connector
• Unusual
• Requires a transceiver to convert to RJ45
UTP Straight Through Cable
One end: ow o gw bl blw g brw br
One end: ow o gw bl blw g brw br
1 2 3 4 5 6 7 8
Transmit
Used for:
Switch
 router
Computer  switch
Computer  hub
Receive
Crossover Cable
1 2
One end: ow o
One end: gw g
3 6
Used for:
Router
 router
Computer  computer
Computer  router
Switch
 switch
Switch
 hub
3 4
gw bl
ow bl
1 4
5 6 7 8
blw g brw br
blw o brw br
5 2 7 8
Roll-over Cable
1 2 3 4 5 6 7 8
One end: ow o gw bl blw g brw br
One end: br brw g blw bl gw o ow
8 7 6 5 4 3 2 1
Hubs
• Multiport repeater
• Concentrators – central connection point
• Active – has power
• re-generates signal & sends out all ports except receiving
• Intelligent – active
• microchip w/diagnostics
• expensive
• good for troubleshooting
• Passive – no power
• connection point
• does not regenerate the signal
5-4-3 Rule
• No more than 5 segments connect using 4 hubs
• Only 3 segments can have hosts
• Ensures that the signal reaches the destination
within a specified time limit to avoid collisions..
Wireless
• RF
• Infrared – req line of site
• Microwaves
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No wires
Mobile
Versatile
Convenient
Bridges
• Data link layer
• Connects network segments
• Builds MAC table of hosts on each segment
• Filter – looks at the destination MAC address, drops the
frame if the destination is on the same segment.
• Flood – doesn’t have destination MAC address in the bridge
table, sends out all ports except receiving one..
• Forward – picks up frame and forwards out to the correct
segment
Switch
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Multiport bridge
Makes decisions based on MAC address
Builds MAC table (switching table)
Reduce traffic
Increase bandwidth
Filter
breaks up
Flood
collision domain
Forward
NIC
• Printed circuit board providing network
connectivity
• Operates @ layers 1 and 2 but it is considered
a layer 2 device
• MAC address
Peer to Peer Networks
• Computers connected to act as equal partners
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No centralized administration
Ea. computer may act as a server or client to other computers
10 or fewer
Share files
Share printers
• Easy to install
• Does not scale well
• Security is low
Client/Server
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Centralized control
Common admin
Increased security
Scalable – requires authentication
Server – additional processing power
RAM
• Single point of failure
WANs
• Networks connected together over a
wide geographic area.
• Use serial connections
• Bits of data are transmitted sequentially over a
single channel
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Dedicated leased lines
ISDN
DSL
Cable
Leased Lines
• T1 – 1.544 Mbps
• T3 – 44.736 Mbps
• Run PPP or Frame Relay Encapsulations
• PPP – Point to Point Protocol
• Frame Relay
ISDN
• Integrated Services Digital Network
• 128 kbps
• Dial on demand connections
• BRI (Basic Rate Interface)
• 2 B channels (64 kbps bearer channels) - data
• 1 D channel (16 kbps delta channel) – signaling and link
management
• Typically uses PPP encapsulation.
DSL
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Digital Subscriber Line
128 kbps – 6.1 Mbps
Dial-up connectivity
Uses telephone infrastructure
Cable
• Up to 8 Mbps (maybe higher?)
• Uses existing cable tv infrastructure
• Coaxial cable
Router Purpose
• Route packets from source to destination with a
LAN
• Provide connectivity from the LAN to the WAN.
• Segments a network into subnetworks
• Breaks up broadcast domains.
Router WAN Serial Ports
• V.35 connectors
• DTE (data terminal equipment) – on the customer side
of the connection
• DCE (data circuit-terminating equipment) on the ISP
side.
• Provides clock rate
• CSU/DSU – channel service unit/data service unit
• Another device that provides clocking with a direct
connection.
Configuring the Router
• Need management connection
• Roll-over cable/console cable
• Connects serial port of computer using DB9 to RJ45 transceiver to Console
port (RJ45) on the router
• Terminal emulation software
• Hyperterminal w/these settings on the COM port
• 9600 bps
• 8 data bits
• No parity
• 1 stop bit
• None
Console v. Auxiliary Port
• Console port is used for initial router configuration
• Console management connection is between a pc and
the router console port.
• Management via a modem connection is possible for
configuration changes.
• Modem is connected to the auxiliary port
Cisco 2500 Router
• DB-15 port
• Requires a transceiver to convert to a Ethernet
port (RJ45)