Connecting to the Internet Through an ISP

© 2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1

Connecting to the Internet Through an ISP

Networking for Home and Small Businesses – Chapter 4

ITE PC v4.0Chapter 1 2© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

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


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


4.1.2 Internet Service Providers (ISPs)

Internet Service ProvidersGive users access to internet resources

Allow organizations and individuals to publish information on the internet


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


4.1.4 Options for Connecting to the ISP

Identify and describe the different connection options that ISPs can provide


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)


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


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.


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.


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


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


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

4.2.3 Forwarding Packets Across the Internet


4.3.1 Internet Cloud


4.3.2 Devices in Internet Cloud

DSL Access Multiplexer (DSLAM) Cable Modem Termination System (CMTS)




4.3.3 Physical and Environmental Requirements

Physical requirements of a home network versus an ISP


4.4.1 Common Network Cables

Twisted Pair is used for Ethernet



Unshielded twisted pair (UTP) is the most commonly encountered type of network cable in North America to connect hosts, workstations, and other networking devices


4.4.3 Coaxial Cable Provides improved shielding compared to UTP, so has a lower

signal-to-noise ratio

More difficult to install


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

4.4.4 Fiber Optic Cables


4.5.1 Cabling Standards


4.5.2 UTP Cables Identify and describe the cross-over and straight through cable pinouts

and color codes


4.5.2 UTP Cables Identify and describe the cross-over and straight through cable pinouts

and color codes


4.5.2 UTP Cables

Identify and describe the cross-over and straight through cable pinouts and color codes


4.5.3 UTP Cable Termination

Lab 4.5.3.2 – Building Straight-Through and

Crossover UTP Cables


4.5.4 Terminating UTP at Patch Panels and Wall Jacks


4.5.5 Cable Testing


4.5.5 Cable Testing


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 pairsnear the transmitting end - NEXT

measured at the receiving end of the cable – FEXT


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


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 high-voltage 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.


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.








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, high-speed 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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Connecting to the Internet Through an ISP