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Chapter 3
NETWORK
CONNECTION
HARDWARE
Chapter 3: NETWORK CONNECTION HARDWARE
NETWORK INTERFACE ADAPTER
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Provides the link between a computer and the
network

Requires a device driver to perform both data-link
and physical layer functions

Plugs into a bus slot or universal serial bus (USB)
port on a computer

Also referred to as a network interface card (NIC)
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Chapter 3: NETWORK CONNECTION HARDWARE
A NETWORK INTERFACE ADAPTER
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TRANSMISSION FUNCTIONS
 Network interface adapters perform the following
functions during data transmission:
 Data transfer, buffering, and encapsulation
 Media Access Control (MAC)
 Parallel/ serial conversion
 Signal encoding and amplification
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NETWORK INTERFACE ADAPTER FEATURES
 Multiple duplex modes and autonegotiation of
modes
 Processor offloading features
 Bus mastering
 Checksum processing
 Transmission Control Protocol (TCP) segmentation
 IP Security (IPSec) processing
 Network management
 Wake on LAN
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HALF-DUPLEX AND FULL-DUPLEX MODES
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SELECTION CRITERIA
 When selecting network interface adapters, you must
consider the following:
 The data-link layer protocol being implemented and the specific
standard
 The transmission speed requirements for the local area network
(LAN)
 The specific cabling and connector types that will be used
 Each computer’s bus architecture and resource availability
 Network interface driver availability
 The operating system type
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INSTALLING A NETWORK INTERFACE ADAPTER
IN A COMPUTER
NIC Installation
To install a network interface adapter:
1. Physically insert the network interface adapter
card into the slot.
2. Configure the card to use the appropriate hardware
resources.
3. Install the card’s device driver.
Chapter 3: NETWORK CONNECTION HARDWARE
A NETWORK INTERFACE ADAPTER IN A
COMPUTER
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CONFIGURING A NETWORK INTERFACE
ADAPTER
 Network interface adapters that do not support plug
and play (PnP) must be manually configured for
some or all of the following hardware resources:
 Interrupt request (IRQ)
 I/O
 Memory address
 Direct memory access (DMA) channel
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NETWORK INTERFACE ADAPTER DEVICE
DRIVERS
 Network interfaces require a device driver to provide
the link between the computer and the interface.
 Operating systems ship with device drivers for
common interfaces.
 Operating systems that support PnP detect and
configure the interface automatically.
 You can get drivers from the manufacturer’s Web
site.
 The driver configuration must match the interface’s
resource settings.
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TROUBLESHOOTING A NETWORK INTERFACE
ADAPTER
 To troubleshoot the suspect network interface
adapter, open the computer case and do the
following:
 Verify that the interface is seated properly in the bus
slot.
 Remove the card, clean the slot, and then reseat the
card in the same slot or try another slot.
 Test a different interface (known to be functional) in
the same slot and in a different slot
Chapter 3: NETWORK CONNECTION HARDWARE
PHYSICAL, DATA-LINK, AND NETWORK LAYER
HARDWARE
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HUBS, REPEATERS, AND CONCENTRATORS
 Hubs, repeaters, and concentrators are all physical
layer devices that
 Amplify and repeat signals
 Extend the distance of a network
Chapter 3: NETWORK CONNECTION HARDWARE
THICK ETHERNET REPEATERS
 Thick Ethernet repeaters extend the distance of a
bus network.
 The maximum segment length is 500 meters.
 The maximum network distance is 2500 meters.
 You must observe the 5-4-3 rule.
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THIN ETHERNET REPEATERS
 Thin Ethernet repeaters extend the distance of a bus
network.
 The maximum segment length is 185 meters.
 The maximum network distance is 925 meters.
 You must observe the 5-4-3 rule.
Chapter 3: NETWORK CONNECTION HARDWARE
AN ETHERNET REPEATER
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10BASE-T AND 100BASE-X HUBS
 10Base-T and 100Base-TX/100Base-T4 standards define
Ethernet networks that function at 10 Mbps and 100 Mbps,
using baseband signaling over twisted-pair wire.
 10Base-T
 Maximum distance limitation for each connection: 100 meters,
including workstation-to-hub and hub-to-hub connections
 Can have up to four hubs connected to form a hierarchical star
 Includes an internal crossover circuit
 Uses an uplink port to form a hierarchical star
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10BASE-T AND 100BASE-X HUBS (CONT.)
 100Base-TX and 100Base-T4
 There are two types of hubs: Class I and Class II.
 The maximum distance for each node connection is
100 meters.
 Class II hub-to-hub connections can be no more than
5 meters long.
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HUB CONNECTIONS
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Play Video
Chapter 3: NETWORK CONNECTION HARDWARE
10BASE-T HUB
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BRIDGES AND SWITCHES
 Are data-link layer devices that use destination
addresses to forward frames
 Are protocol independent
 Do not filter broadcast packets
 Do not define separate networks
 Two forwarding modes in switches: cut-through and
store-and-forward
 One forwarding mode in bridges: store-and-forward
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CUT-THROUGH SWITCHING
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Hubs & Switches
 The cut-through method is the fastest way to
forward frames.
 Looks at only the first 6 bytes (destination MAC
address) before forwarding
 Does not perform cyclical redundancy check (CRC) on
the frame contents
 Does not define separate collision domains
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STORE-AND-FORWARD SWITCHING
 Store-and-forward switching is slower but more
reliable than the cut-through method of forwarding
frames.
 Store-and-forward switching pulls in the entire
frame and performs a CRC check on the frame
contents.
 Each port defines a separate collision domain.
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TRANSPARENT BRIDGING AND SWITCHING
Perform three basic functions:
 Flood
 Frames with unidentified destination addresses are transmitted
out all ports except the one they were received through.
 Learn
 Switches use the source addresses within frames to learn which
devices use specific ports, and then they use this information to
build their internal address tables.
 Forward
 Frames are selectively forwarded to a port using known
destination addresses stored in the MAC address table.
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FLOODING AND LEARNING
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FORWARDING
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OTHER BRIDGING TECHNOLOGIES
 Source route bridging
 Source route bridging is used in Token Ring networks.
 The source host determines the path through the network, not
the bridge.
 Bridges add path information when frames are forwarded and
use this information to continue to forward frames between
source and destination hosts.
 Translation bridging
 Translation bridging is used to connect dissimilar data-link
architectures.
 Remote bridge
 A remote bridge connects two segments across a wide area
network (WAN) link.
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OTHER DATA-LINK LAYER TECHNOLOGIES
 Spanning tree protocol
 Used to avoid bridging loops
 Ensures a single active path to all segments within a
LAN
 Virtual LANs (VLANs)
 Are logical LANs defined on switches
 Layer 3 switches
 Have built-in routing capabilities
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SPANNING TREE
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VLANS
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ROUTERS
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Bridges & Routers
Routers are network layer devices that connect LANs.
 Connect similar or different data-link layer LANs
 Must understand and support the network layer protocol and
addressing
 Perform fragmentation
 Strip the data-link header and footer off received frames
 Add a new data-link header and footer before transmitting
frames
 Use routing protocols to build routing tables and forward
frames
 Define separate broadcast domains
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A SIMPLE ROUTED NETWORK
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A ROUTED INTERNETWORK
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GATEWAYS
 Can include the functions of all seven layers of the
OSI model
 Connect dissimilar systems and protocols
 Perform translation and conversion services
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SUMMARY
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Network interface adapters provide the physical link between computers
and the network.
Hubs are physical layer devices that amplify and repeat signals out all
ports except the one they were received through.
Bridges and switches are data-link layer devices that use destination
addresses to forward frames.
Spanning tree is used by bridges and switches to avoid loops.
VLANs are logical LANs used to group computers within a switched
network.
Routers are network layer devices that forward datagrams between
LANs.
Gateways translate and convert protocols between dissimilar systems.