Connecting to the
Network
Networking for Home and Small Businesses – Chapter 3
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Objectives

Explain the concept of networking and the benefits of
networks.

Explain the concept of communication protocols.

Explain how communication occurs across a local
Ethernet network.

Describe Access layer devices and communication
methods on a local Ethernet network.

Describe Distribution layer devices and
communication methods across networks.

Plan, implement, and verify a local network.
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Networking and Its Benefits
 Define the term network and identify various types of
networks
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Networking and Its Benefits
 Small home networks connect a few
computers together and to the
internet
 Small office/home office (SOHO)
networks connect home computers
to a corporate network
 Medium to large networks have
multiple locations and hundreds of
thousands of computers
 World Wide networks connect
hundreds of millions of computers
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Networking and Its Benefits
 Define the components of an Information network
Hosts
Shared Peripherals
Networking Devices
Networking Media
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Networking and Its Benefits
 Describe the Roles of computers on a network
 Clients and servers
 Servers provide a service
E-mail
Web Site
FTP Server (File downloads)
 Clients access services
Outlook, Eudora
Internet Explorer, Firefox
FTP Client, Filezilla
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Peer-to-Peer Networks
 Build computer peer-to-peer network and verify
 Peer-to-peer networks are typically used for 10 or fewer
clients
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Network Topologies
 Logical topology diagrams include naming and IP
address schemes
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Source, Channel, Destination
 Source: person with the message
 Destination: target of the message
 Channel: voice
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Rules of Communication
 Attributes of a communication protocol:
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Message Encoding
 Thoughts are encoded into language
 Language is transmitted to recipient
 Like language computer data is converted to bits before it is
sent over the wire
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Message Formatting
 Messages must follow a particular format—like a letter or
phone call
 Messages are encapsulated (addressed) before being sent
to the appropriate location
 On a network messages are formatted into frames
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Message Size
 Messages have size restrictions depending on the
channel used
 Messages must be of a particular size
 Ethernet message sizes are limited to 46-1500 bytes
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Message Timing
 Access method
Determines when a message can be sent
This helps avoid collisions
 Flow control
Determines how much information can be sent at any given
time
 Response timeout
Determines what action to take if there is no response in a
reasonable time period
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Message Patterns
 Unicast: Message to a single entity
 Multicast: Message to a group
 Broadcast: Message to everyone
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Communication Protocols
 Attributes of a communication protocol:
Message format
Message size
Timing
Encapsulation
Encoding
Standard message pattern
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Importance of Protocols
 Network devices must follow the protocols to
communicate with one another
 The Ethernet protocol defines local network
communication including message format, message
size, timing, encoding, and message patterns.
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Standardization of Protocols
 Standards are beneficial to
networking in many ways:
Facilitate design
Simplify product development
Promote competition
Provide consistent interconnections
Facilitate training
Provide more vendor choices for
customers
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Standardization of Protocols
 Example: 802.3 100BASE-T represents the 100 Megabit
Ethernet using twisted pair cable standards
100 is the speed in Mbps
BASE stands for baseband transmission
T stands for the type of cable, in this case, twisted pair
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Physical Addressing
 Physical addressing identifies Source, Destination and
Channel on an Ethernet Network
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Ethernet Communication
 Describe some of the basic characteristics of Ethernet
for communicating across the channel
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Hierarchical Design of Ethernet Networks
 Access Layer - to
provide connections to
hosts in a local Ethernet
network.
 Distribution Layer - to
interconnect the smaller
local networks.
 Core Layer - a highspeed connection
between distribution
layer devices.
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Logical Addressing
 IP addresses are considered logical addresses
 IP addresses have a host portion and a network portion
 Both IP addresses and MAC addresses are required for
communication
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Access and Distribution Layer Devices
 Switches and hubs are access layer device that allows
multiple computers to connect to the network
 Routers are distribution layer devices that allow multiple
networks to communicate with one another
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Access Layer
 The access layer allows multiple devices to connect to
the network
 Devices such as phones, printers, computers, servers,
etc. all connect at the access layer
 Hubs and switches are access layer devices
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Function of Hubs
 Hubs ONLY broadcast messages
 Hubs are considered Layer 1 devices (OSI Model)
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Functions of Switches
 Switches send unicast messages to the destination
 Switches learn MAC addresses by “flooding”
 Switches are Layer 2 devices (OSI Model)
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Broadcast Messages
 Broadcast messages allow a host to send a message to all
other hosts on the network while sending the message
only once
 The broadcast MAC address is FFFF.FFFF.FFFF
 If a host sends a message to a hub it is broadcast to all
hosts on the network
 A local network is referred to as a broadcast domain
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Switch Behavior
 When a switch receives data from a host with a MAC
address not listed in it’s MAC table it adds that address to
the table
 When a switch receives a frame with a destination MAC
address not in it’s table it floods the frame to all ports
 When a switch receives a frame with a destination MAC
address in the table, the frame is sent as a unicast
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MAC and IP
 A NIC will only accept a frame if the destination MAC is a
broadcast MAC or it is the NICs MAC
 Most applications rely only on the IP address
 MAC is determined using address resolution protocol
(ARP)
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ARP
 The sender broadcasts a frame including the IP address of
the destination
 All network hosts receive the broadcast, but only the host
with a matching IP address responds by sending it’s MAC
address back to the sender
 The sending host receives the message and stores the
MAC address and IP address information in the ARP
table.
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Distribution Layer Devices and Communication
Methods
 Broadcast containment
 Security
 Locations
 Logical Grouping
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 Describe the function of routers and how they are used
in the network
• A router connects a network to other networks
• Routers rely on packets and logical address
• A packet is the encapsulated data inside a frame
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Default Gateway
 Default Gateways allow devices on one network to
communicate with another network
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Routing Tables
 Routers use IP
addresses to
determine where
traffic should be sent
 Routers are
considered layer 3
devices
 Routers modify MAC
addresses but do not
change IP addresses
of data passing
through
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Tables Maintained by Routers
 ARP Tables are used
to determine the MAC
of the destination
 Routing tables are
used to send traffic
out a specific
interface
 Routing tables can be
updated dynamically
or manually
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Local Area Network (LAN)
 A group of local computers or network devices under
one administrative control
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Adding Network Hosts to Local and Remote
Networks
 Locally: just plug in
 Remotely: requires routing
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Packet Tracer 5.3
 Be sure to do packet tracer activities in the curriculum
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Plan, Implement and Verify a Local Network
 Plan and document the building of a small home or
small business Ethernet network
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Plan and Document an Ethernet Network
 Network planning starts with information gathering:
Number of hosts
Applications used
Sharing and Internet connectivity requirements
Security and privacy considerations
Reliability expectations
Connectivity requirements including, wired and wireless
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Plan and Document an Ethernet Network
 Physical environment
Temperature control and placement of power outlets
 Physical configuration
Location of routers and switches
Device interconnections and cabling
Hardware configuration
 Logical configuration
Location and size
IP addressing
Naming and sharing
Permissions
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Plan, Implement and Verify a Local Network
 Build a virtual model of their small home or small
business network
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Multi-function Device
 Multi-function routers include:
Router
Wireless access point
Switch
Firewall
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Connecting the Linksys Router
 Internet port connects to the Internet
 Ethernet port connects to the Ethernet
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Plan, Implement and Verify a Local Network
 Perform simple workgroup tasks in order to share
resources
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Summary
 Information networks carry data using hosts as clients,
servers, or both.
 All computer communication involves a source,
destination, and channel.
 Rules called protocols govern computer
communications.
 Larger networks are divided into smaller, more
manageable ones using a layered hierarchical design.
 Each network host needs both a physical MAC address
and a logical IP address.
 Good network design requires a network plan.
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