Transcript Connecting to the Internet Through an ISP

Connecting to the
Internet Through an ISP
Networking for Home and Small Businesses – Chapter 4
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Objectives

Explain “what is the Internet?” and how we connect to
the Internet using an Internet Service Provider (ISP).

Explain how information is sent across the Internet
through an ISP.

Describe and identify the components of an ISP
Network Operations Center.

Identify the different types of cables and connectors
for connecting the devices in a Network Operations
Center.

Construct and terminate twisted pair cables and
determine type of cable needed
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4.1.1 Explain What the Internet Is
 The Internet is a network of networks that connects
users in every country in the world.
 Users are connected to ISPs
 ISPs are connected to other ISPs
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4.1.2 Internet Service Providers (ISPs)
 Internet Service Providers
Give users access to internet resources
Allow organizations and individuals to publish information on the internet
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4.1.3 The ISPs Relationship With the Internet
 ISPs use a POP to provide service to end users
 There are many POPs in an ISPs network
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4.1.4 Options for Connecting to the ISP
 Identify and describe the different connection options
that ISPs can provide
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4.1.4 Options for Connecting to the ISP
 Dialup (56 Kb Modem)
 Cable
 Digital Subscriber Line
 Leased Line (T-1)
 Satellite
 Cell Modem (Air Card)
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4.1.5 ISP Levels of Services
 Various services are available
(see graphic)
 Most ISPs offer two different
contract levels: home service
or business class service.
 Asymmetric
Different upload and download
speeds
Used for home
 Symmetric
Same upload and download
speeds
Used for business
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4.2.1 Importance of the Internet Protocol (IP)
 Must run Internet Protocol (IP) software to
communicate on Internet
 IP protocol is one of the TCP/IP (Transmission
Control Protocol / Internet Protocol) Protocols
 As Ethernet uses Frames, IP uses Packets
 Each IP packet must contain a valid source and
destination IP address.
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4.2.1 Importance of the Internet Protocol (IP)
 The IP Packet (datagram)
• Has a header which
contains the source
and destination IP
addresses
• IP addresses must be
unique on the
Internet.
• Computers in homes,
small businesses and
other organizations
obtain their IP
configuration from
their ISP.
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4.2.2 How ISPs Handle Packets
 Messages are divided into packets – size between 64 to 1500 bytes for
Ethernet
 Downloading a single 1 MB song would require over 600 packets of 1500
bytes.
 Each individual packet must have a source and destination IP address.
 Packets or datagrams contain IP address and control information
 IP addresses are granted to ISPs from a regional Internet registry (RIR)
 RIR North America: ARIN (http://www.arin.net)
 Internet Assigned Numbers Authority: responsible for IP addressing
 Internet Corporation for Assigned Names and Numbers: responsible for
names and IP addressing
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4.2.2 How ISPs Handle Packets
 NOC controls the flow of traffic
 Sends traffic to remote networks if necessary
 Contains services: e-mail, web
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4.2.3 Forwarding Packets Across the Internet
 ping - tests end-to-end connectivity between source and destination
 traceroute - traces the route from source to destination, displays each
router and 3 Round Trip Times (RTT)
 Packets are sent from router to router until they reach their destination
 PACKET TRACER 4.2.3.2
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4.3.1 Internet Cloud
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4.3.2 Devices in Internet Cloud
DSL Access Multiplexer (DSLAM)
Cable Modem Termination System (CMTS)
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4.3.3 Physical and Environmental Requirements
 Physical requirements of a home network
versus an ISP
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4.4.1 Common Network Cables
 Twisted Pair is used for Ethernet
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Unshielded twisted pair (UTP) is the most commonly
encountered type of network cable in North America to
connect hosts, workstations, and other networking devices
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4.4.3 Coaxial Cable
 Provides improved shielding compared to UTP, so has a lower
signal-to-noise ratio
 More difficult to install
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4.4.4 Fiber Optic Cables
 Provides improved shielding compared to UTP, so has a lower signal-to-noise ratio and
can therefore carry more data
 Used in enterprise environments and large data centers
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4.5.1 Cabling Standards
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4.5.2 UTP Cables
 Identify and describe the cross-over and straight through cable pinouts
and color codes
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4.5.2 UTP Cables
 Identify and describe the cross-over and straight through cable pinouts
and color codes
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4.5.2 UTP Cables
 Identify and describe the cross-over and straight through cable pinouts
and color codes
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4.5.3 UTP Cable Termination
Lab 4.5.3.2 – Building
Straight-Through and
Crossover UTP
Cables
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4.5.4 Terminating UTP at Patch Panels and
Wall Jacks
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4.5.5 Cable Testing
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4.5.5 Cable Testing
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4.5.5 Cable Testing
 Attenuation - commonly referred to as insertion loss, is
a general term that refers to the reduction in the
strength of a signal
 Crosstalk is the leakage of signals between pairs
near the transmitting end - NEXT
measured at the receiving end of the cable – FEXT
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4.5.6 Cabling Best Practices
 Label the cables on both ends
 Use cable ties to dress cables
 Use consistent cable coloring (red for crossover, blue for windows
network, grey for linux network, etc)
 Test ALL cables before installing in a production network
 Install cable away from EMI
 Follow cable standards
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 The following steps, called best practices, ensure that cable
termination is successful.
 1. It is important that the type of cables and components used on a
network adhere to the standards required for that network. Modern
converged networks carry voice, video and data traffic on the same
wires; therefore the cables used on converged networks must be
able to support all these applications.
 2. Cable standards specify maximum lengths for different types of
cables. Always adhere to the length restrictions for the type of
cable being installed.
 3. UTP, like all copper cable, is susceptible to EMI. It is important
to install cable away from sources of interference such as highvoltage cables and fluorescent lighting. Televisions, computer
monitors and microwaves are other possible sources of
interference. In some environments it may be necessary to install
data cables in conduit to protect them from EMI and RFI.
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 The following steps, called best practices, ensure that cable
termination is successful.
 4. Improper termination and the use of low quality cables and
connectors can degrade the signal carrying capacity of the cable.
Always follow the rules for cable termination and test to verify that
the termination has been done properly.
 5. Test all cable installations to ensure proper connectivity and
operation.
 6. Label all cables as they are installed, and record the location of
cables in network documentation.
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Summary
 The Internet is a worldwide collection of computer networks,
accessed through ISPs.
 Internet Protocol (IP) controls the structure and addressing of data
packets for transport through the Internet cloud.
 ISP Network Operations Centers (NOCs) utilize high-end, highspeed devices with redundancy.
 Home networks feature multi-function devices which perform
switching and routing.
 Networks use physical cabling media which must conform to
standards in construction and termination.
 Cabling best practices are designed to reduce attenuation and
crosstalk.
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