Transcript Chp. 1 - Cisco Networking Academy

The Internet
and Its Uses
Discovery 2: Chapter 1
Version 4.1
Objectives
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Describe Internet standards
Describe the purpose of an ISP
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Describe the hierarchical structure of the Internet
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Services offered
Types of connections
High Speed Connection Types
The purpose of the Point of Presence (POP)
The purpose of an Internet Exchange Point (IXP)
Identify the 3 Tiers of ISPs
Identify the types of devices used by the ISPs
Describe the importance of scalability in the ISP network.
Describe the various network support teams that work at an
ISP and the roles and responsibilities of each one.
Contents
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1.1: What is the Internet
1.2: ISPs
1.3: ISP Connectivity
1.1: What is the Internet
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A worldwide, publicly accessible network of
networks.
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Business uses of the Internet:
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E-commerce
Communications
Collaboration and training
Internet Evolution
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In the beginning, the Internet was used
strictly for scientific, educational, and
military research.
In 1991, regulations changed to allow
businesses and consumers to connect as
well.
Internet Standards
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A standard is a set of rules for how something
must be done.
Networking and Internet standards ensure that
all devices connecting to the network use the
same set of rules.
Using standards, it is possible for different types
of devices to send information to each other over
the Internet.
Internet standards are the product of a cycle of
discussion, problem solving, and testing.
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When a new standard is proposed, each stage of the
development and approval process is recorded in a
numbered Request for Comments (RFC) document so
that the evolution of the standard is tracked.
Internet Standards
ISPs
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Every device must connect to the Internet
through an ISP
An ISP is a company or organization
through which a subscriber obtains
Internet access.
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A subscriber can be a business, a private
consumer, a government body, or even another
ISP.
ISP Services
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Equipment co-location - A can have some or all of its
internal network equipment physically located on the
ISP premises.
Web hosting - provides the server and application
software for storing web pages and web content for the
business website.
FTP - provides the server and application software for
the FTP site of a business.
Applications and media hosting - provides the server
and software to allow a business to provide streaming
media such as music, video, or applications such as
online databases.
Voice over IP - (VoIP)
Technical support - provide technical support and
consulting services for an additional fee.
ISP Services
1.2: ISP Connection Types
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An ISP can offer its clients many ways to connect
Dialup access
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DSL
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Continuous digital connection over phone line
More expensive, faster
Uses a special high-speed modem that separates the DSL signal from the
telephone signal Uses
Cable Modem
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uses any phone line and a modem
Inexpensive, but slow
The user must call the ISP access phone number
used by mobile workers, remote areas
Internet signal is carried on coaxial cable
Uses a special cable modem
Satellite
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User connects through Ethernet to a satellite modem
Modem transmits radio signals to the nearest Point of Presence in the
satellite network.
Connections to ISPs
ISP Bandwidth
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Bandwidth is measured in bits per second
(bps).
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kilobits per second (kbps)
megabits per second (Mbps)
gigabits per second (Gbps)
High-Bandwidth Connections
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Larger businesses and organizations need
higher-bandwidth connections to the ISP
There are three main types of highbandwidth connection options that are used
by businesses:
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T1 connections
T3 connections
Metro Ethernet
T1 & E1
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T1 is transmits data at rates of up to 1.544
Mbps
Symmetrical connection: upload &
download bandwidth are the same
A medium-sized business may need only
one T1 connection.
E1 is a European standard that transmits
data at 2.048 Mbps.
T3 & E3
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T3 connections transmit data up to 45
Mbps.
more expensive than T1
Used by larger businesses
Large businesses with multiple locations
might use a combination of T1 and T3
lines.
E3 is a European standard that transmits
data at 34.368 Mbps.
Metro Ethernet
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Metro Ethernet offers a wide range of highbandwidth options, usually at Gbps speeds
Metro Ethernet refers to network systems based
on Ethernet technologies, that cover a
metropolitan area
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uses switched technology
Large companies with many branches in the
same city, such as banks, use Metro Ethernet.
Metro Ethernet allows the transfer of large
amounts of data faster and less expensively than
other high-bandwidth connection options.
High-Bandwidth Connections
POP
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The point at which individual computers and business
networks connect to the ISP is called the POP (point of
presence)
POPs are connection/concentration centers located at the
edge of the ISP network and serve a particular geographical
region.
They provide a local point of connection and authentication
(password control) for multiple end users.
An ISP may have many POPs, depending on the size of the
POP and the area that it services.
Within the ISP network, high-speed routers and switches
move data between the various POPs.
Multiple links interconnect the POPs to provide alternate
routes in case one of the links becomes overloaded with
traffic or fails.
POPs at the ISP
Internet Hierarchy
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The Internet has a hierarchical structure.
At the top of this hierarchy are the ISP
organizations.
The ISP POPs connect to an Internet
Exchange Point (IXP).
In some countries, this is called a Network Access
Point (NAP).
An IXP or NAP is where multiple ISPs join together to
1. gain access to each other's networks and exchange
information.
2. Access the Internet backbone
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There are currently over 100 major exchange
points located worldwide.
Internet Hierarchy
Internet Backbone
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The Internet backbone consists of the group of
major ISP networks interconnected through IXPs
and private peering connections (direct
connections)
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owned by various organizations
The Internet backbone is like an information super
highway that provides high-speed data links to
interconnect the POPs and IXPs in major
metropolitan areas around the world.
The primary medium that connects the Internet
backbone is fiber-optic cable.
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This cable is typically installed underground to connect
cities within continents.
Fiber-optic cables also run under the sea to connect
continents, countries, and cities.
Internet Backbone
ISP Tiers
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ISPs are classified into different tiers
according to how they access the Internet
backbone:
 Tier 1 – access backbone directly by
private peering with each other
 Tier 2 – connect to the backbone through
a Tier 1 ISP, an IPX or private peer with
other ISP
 Tier 3 – connect to the backbone through
Tier2s and Tier 1s
ISP Hierarchy
Tier 1 ISPs
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Very large organizations that are directly
connected to and own the Internet
backbone (cover an entire continent)
These ISPs connect directly with each
other through private peering, physically
joining their individual network backbones
together to create the Internet Backbone
Tier 1 ISPs own the routers, high-speed
data links, and other pieces of equipment
that join them to other Tier 1 ISP networks
(even undersea cables)
Tier 2 ISPs
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Tier 2 ISPs can connect to the Internet
Backbone in 3 ways:
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Pay a Tier 1 ISP to carry their traffic to other
parts of the world
Connect directly to an IXP
Connect to other ISPs with private peering
Can also be very large, but don’t span
entire continents or between continents
Tier 3 ISPs
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Tier 3 ISPs are the farthest away from the
backbone.
These are generally found in major cities
and provide customers local access to the
Internet.
Tier 3 ISPs pay Tier 1 and 2 ISPs for
access to the global Internet and Internet
services.
Network Utilities
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Network utilities can be used to create a map of
the various interconnections to visualize how ISP
networks interconnect.
These utilities can also illustrate the speed at
which each connecting point can be reached.
 Ping
– tests connectivity between 2
hosts
 Traceroute – used to troubleshoot
connectivity problems
Ping
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Ping tests the accessibility of a specific IP
address.
Ping sends an ICMP (Internet Control Message
Protocol) echo request packet to the destination
address and then waits for an echo reply packet
to return from that host.
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ICMP is an Internet protocol that is used to verify
communications.
It measures the time that elapses between when the
request packet is sent and the response packet is
received.
The ping command output indicates whether the
reply was received successfully and displays the
round-trip time for the transmissions.
Traceroute
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Traceroute displays the path that a packet
takes from the source to the destination host.
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Traceroute displays each hop along the way.
It also calculates the time between when the
packet is sent and when a reply is received from
the router at each hop.
You can use the output of the traceroute utility to
help determine where a packet was lost or
delayed.
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Each router that the packet passes through is called a hop
The output also shows the various ISP organizations that
the packet must pass through during its journey from
source to destination.
In windows, the command is tracert
Network Testing
1.3: ISP Connectivity
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An ISP requires a variety of devices to
accept input from end users and provide
services.
To participate in a transport network, the
ISP must be able to connect to other ISPs.
An ISP must also be able to handle large
volumes of traffic.
ISP Devices
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Some of the devices required for an ISP to provide
services include:
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Access devices that enable end users to connect to the ISP
 DSLAM (DSL), CMTS (cable), modems, wireless bridging
equipment (wireless)
Border Gateway Routers
 enable the ISP to connect and transfer data to other ISPs,
IXPs, or large business enterprise customers.
Servers
 Hosting of services
Power conditioning equipment
 Maintain power continuity
High-capacity air conditioning
ISP Devices
ISP Growth Requirements
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ISPs, like other businesses, usually want to
expand so that they can increase their income.
The ability to expand their business depends on
gaining new subscribers and selling more
services.
However, as the number of subscribers grows,
the traffic on the network of the ISP also grows.
Eventually, the increased traffic may overload the
network, causing router errors, lost packets, and
excessive delays.
This requires the ISP network to be expandable
Scalability
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Scalability is the capacity of a network to
allow for future change and growth.
Scalable networks can expand quickly to
support new users and applications without
affecting the performance of the service
being delivered to existing users.
The most scalable network devices are
those that are modular and provide
expansion slots for adding modules.
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Modules can have different numbers of ports and
allow for different connection types
ISP Roles
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ISPs consist of many teams and departments
which are responsible for ensuring that the network
operates smoothly and that the services are
available.
Network support services are involved in all
aspects of network management, including planning
and provisioning of new equipment and circuits,
adding new subscribers, network repair and
maintenance, and customer service for network
connectivity issues.
When a new business subscriber orders ISP
services, the various network support service teams
work together to ensure that the order is processed
correctly and that the network is ready to deliver
those services as quickly as possible.
ISP Roles
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Roles and responsibilities within an ISP:
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On-site Installation
Customer Service
Planning and Provisioning
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NOC (network operations center)
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Identifies whether existing network and
hardware and circuits are available
monitoring & testing
Help Desk