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- Identify functions of LAN connectivity hardware
- Install and configure a network adapter (network interface card)
- Identify problems associated with connectivity hardware
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- Describe the factors involved in choosing a network adapter, hub,
switch, or router
- Describe the functions of repeaters, hubs, bridges, switches, and
gateways
- Describe the uses and types of routing protocols
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- Also called network interface cards (NICs)
- Connectivity devices enabling a workstation, server, printer, or other
node to receive and transmit data over the network media
- In most modern network devices, network adapters contain the data
transceiver
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- For a desktop or tower PC, network adapter is likely to be a type of expansion
board
- Expansion boards connect to the system board through expansion slots
- The circuit used by the system board to transmit data to the computer’s
components is the computer’s bus
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- PC bus types you may encounter:
- Industry Standard Architecture (ISA)
- MicroChannel Architecture (MCA)
- Extended Industry Standard Architecture (EISA)
- Peripheral Component Interconnect (PCI)
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- PCMIA
- Developed in early 1990s to provide standard interface for connecting
any type of device to a portable computer
- More commonly known as PC Cards
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- USB (universal serial bus) port
- Standard external bus that can be used to connect multiple types of
peripherals
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- To install modern network adapters, first install hardware, then install
software shipped with NIC
- In some cases you must perform a third step:
- Electrically erasable programmable read-only memory (EEPROM)
- Type of ROM found on a circuit board
- Configuration information can be erased and rewritten through
electrical pulses
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- Jumper
- Small, removable piece of plastic that contains a metal receptacle
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- DIP switch
- Small, plastic toggle switch that represents “on” or “off” status
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- Ensure that the correct device driver is installed for the network
adapter and that it is configured properly
- Device driver
- Software that enables an attached device to communicate with computer’s
operating system
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- Message to the computer that instructs it to stop what it is doing and
pay attention to something else
- An interrupt is the wire on which a device issues voltage to signal this
request
- Each interrupt must have a unique IRQ number
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- When two devices attempt to use the same IRQ, any of the following
problems may occur:
- Computer may lock up or “hang” either upon starting or when operating
system is loading
- Computer may run much slower than usual
- Though computer’s network adapter may work properly, other devices may
stop working
- Video or sound card problems may occur
- Computer may fail to connect to the network
- Computer may experience intermittent data errors during transmission
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- CMOS (complementary metal oxide semiconductor)
- Firmware on a PC’s system board that enables you to change its devices’
configurations
- Information saved in CMOS is used by the computer’s BIOS (basic
input/output system)
- BIOS is a simple set of instructions enabling a computer to initially
recognize its hardware
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- Memory range
- Hexadecimal number indicating the area memory that the network adapter
and CPU will use for exchanging, or buffering, the data
- Base I/O port
- Setting that specifies, in hexadecimal notation, which area of memory
will act as a channel for moving data between the network adapter and
CPU
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- Once you have adjusted the network adapter’s system resources, you may
need to modify its transmission characteristics
- These settings are held in the adapter’s firmware
- Loopback plug
- Plugs into port and crosses over the transmit line to the receive line
so that the outgoing signal can be redirected back into the computer
for testing
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- Connectivity devices that regenerate and amplify an analog or digital
signal
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- Multiport repeater containing multiple ports to interconnect multiple
devices
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- Elements shared by most hubs:
- Ports
- Uplink port
- Port for management console
- Backbone port
- Link LED
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- Elements shared by most hubs (cont.):
- Traffic (transmit or receive) LED
- Collision LED (Ethernet hubs only)
- Power supply
- Ventilation fan
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- Passive hubs
- Intelligent hubs
- Possesses processing capabilities
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- Hubs that serve a group of computers that are isolated from the rest of
the network
- Best suited to small, independent departments, home offices, or test
lab environments
- Disadvantage to using a single hub for many connection ports is that it
introduces a single point of failure on the network
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- Physically designed to be linked with other hubs in a single
telecommunications closet
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- Modular hubs
- Provide a number of interface options within one chassis
- Intelligent hubs
- Also called managed hubs
- Network administrators can store the information generated by
intelligent hubs in a MIB (management information base)
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- As with network adapters, the best way to ensure a hub is properly
installed is to follow the manufacturer’s guidelines
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- Factors to consider when selecting the right hub for your network:
- Performance
- Cost
- Size and growth
- Security
- Management benefits
- Reliability
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- Like a repeater, a bridge has a single input and single output port
- Unlike a repeater, it can interpret the data it retransmits
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- Filtering database
- Collection of data created and used by a bridge that correlates the MAC
addresses of connected workstations with their locations
- Also known as a forwarding table
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- Spanning tree algorithm
- Routine that can detect circular traffic patterns and modify the way
multiple bridges work together, in order to avoid such patterns
- Transparent bridging
- Method used on many Ethernet networks
- Source-route bridging
- Method used on most Token Ring networks
- Translation bridging
- Method that can use different logical topologies
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- Subdivide a network into smaller logical pieces
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- Cut-through mode
- Switching mode in which switch reads a frame’s header and decides where
to forward the data before it receives the entire packet
- Cut-through switches can detect runts, or packet fragments
- Store and forward mode
- Switching mode in which switch reads the entire data frame into its
memory and checks it for accuracy before transmitting the information
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- Virtual local area networks (VLANs)
- Network within a network that is logically defined by grouping its
devices’ switch ports in the same broadcast domain
- Broadcast domain
- Combination of ports that make up a Layer 2 segment and must be
connected by a Layer 3 device
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- Switch capable of interpreting Layer 3 data is called a Layer 3 switch
- Switch capable of interpreting Layer 4 data is called a Layer 4 switch
- These higher-layer switches may also be called routing switches or application
switches
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- Multiport connectivity device
- Can integrate LANs and WANs running at different transmission speeds and
using a variety of protocols
- Routers operate at the Network layer (Layer 3) of the OSI Model
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- Modular router
- Router with multiple slots that can hold different interface cards or
other devices
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- Filter out broadcast transmission to alleviate network congestion
- Prevent certain types of traffic from getting to a network
- Support simultaneous local and remote activity
- Provide high network fault tolerance through redundant components
- Monitor network traffic and report statistics to a MIB
- Diagnose internal or other connectivity problems and trigger alarms
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- Static routing
- Technique in which a network administrator programs a router to use a
specified paths between nodes
- Dynamic routing
- Automatically calculates best path between nodes and accumulates this
information in a routing table
- Hop
- Term used in networking to describe each trip data take from one
connectivity device to another
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- To determine the best path, routers communicate with each other through routing
protocols
- In addition to its ability to find the best path, a routing protocol can
be characterized according to its convergence time and bandwidth
overhead
- Convergence time
- The time it takes for a router to recognize a best path in the event
of a change or outage
- Bandwidth overhead
- Burden placed on an underlying network to support the routing protocol
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- The four most common routing protocols:
- RIP (Routing Information Protocol) for IP and IPX
- OSPF (Open Shortest Path First) for IP
- EIGRP (Enhanced Interior Gateway Routing Protocol) for IP, IPX, and
AppleTalk
- BGP (Border Gateway Protocol) for IP
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- Bridge router
- Also called a brouter
- Industry term used to describe routers that take on some
characteristics of bridges
- Routing switch
- Router hybrid that combines a router and a switch
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- Combination of networking hardware and software that connects two
dissimilar kinds of networks
- Popular types of gateways include:
- E-mail gateways
- IBM host gateways
- Internet gateways
- LAN gateways
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- Network interface cards (NICs) come in a variety of types
- In addition to network adapters that interface with network cabling,
network adapters can be designed for wireless transmission
- Installing a NIC involves attaching it to the bus (or port), installing
the NIC device drivers, and configuring its settings
- Firmware combines software and hardware
- An IRQ is the means by which a device can request attention from the CPU
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- Repeaters are connectivity devices that perform the regeneration of a
digital signal
- At its most primitive, a hub is a multiport repeater
- A MIB is a collection of data used by management programs to analyze
network performance and problems
- Bridges resemble repeaters in that they have a single input and single
output port, but differ from repeaters because they can interpret the
data they transmit
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- Switches, like hubs, subdivide a network into smaller logical pieces
- A switch running in cut-through mode will read a frame’s header and
decide where to forward the data before it receives the entire packet
- In store and forward mode, switches read the entire data frame and check
it for accuracy before transmitting it
- In addition to improving bandwidth, switches can create virtual local
area networks (VLANs)
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- A router is a multiport device that can connect dissimilar LANs and WANs
running at different transmission speeds and using a variety of
protocols
- To determine the best paths across networks, routers communicate with
each other using routing protocols
- The networking industry has adopted the term “brouter” to describe
routers that take on some characteristics of bridges
- Gateways are combinations of networking hardware and software that
connect two dissimilar kinds of networks
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