1. The Internet and Its Uses
Discovery 2: Chapter 1

2. Objectives Describe Internet standards Describe the purpose of an ISP
Services offered
Types of connections
High Speed Connection Types
Describe the hierarchical structure of the Internet
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.

3. Contents
1.1: What is the Internet
1.2: ISPs
1.3: ISP Connectivity

4. 1.1: What is the Internet
A worldwide, publicly accessible network of networks.
Business uses of the Internet:
E-commerce
Communications
Collaboration and training

5. Internet Evolution
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.

6. Internet Standards
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.
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.

7. Internet Standards

8. ISPs Every device must connect to the Internet through an ISP
An ISP is a company or organization through which a subscriber obtains Internet access.
A subscriber can be a business, a private consumer, a government body, or even another ISP.

9. ISP Services
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.

10. ISP Services

11. 1.2: ISP Connection Types
An ISP can offer its clients many ways to connect
Dialup access
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
DSL
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
Internet signal is carried on coaxial cable
Uses a special cable modem
Satellite
User connects through Ethernet to a satellite modem
Modem transmits radio signals to the nearest Point of Presence in the satellite network.

12. Connections to ISPs

13. ISP Bandwidth Bandwidth is measured in bits per second (bps).
kilobits per second (kbps)
megabits per second (Mbps)
gigabits per second (Gbps)

14. High-Bandwidth Connections
Larger businesses and organizations need higher-bandwidth connections to the ISP
There are three main types of high-bandwidth connection options that are used by businesses:
T1 connections
T3 connections
Metro Ethernet

15. T1 & E1 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 Mbps.

16. T3 & E3 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 Mbps.

17. Metro Ethernet
Metro Ethernet offers a wide range of high-bandwidth options, usually at Gbps speeds
Metro Ethernet refers to network systems based on Ethernet technologies, that cover a metropolitan area
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.

18. High-Bandwidth Connections

19. POP
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.

20. POPs at the ISP

21. Internet Hierarchy 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
gain access to each other's networks and exchange information.
Access the Internet backbone
There are currently over 100 major exchange points located worldwide.

22. Internet Hierarchy

23. Internet Backbone
The Internet backbone consists of the group of major ISP networks interconnected through IXPs and private peering connections (direct connections)
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.
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.

24. Internet Backbone

25. ISP Tiers
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

26. ISP Hierarchy

27. Tier 1 ISPs
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)

28. Tier 2 ISPs
Tier 2 ISPs can connect to the Internet Backbone in 3 ways:
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

29. Tier 3 ISPs 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.

30. Network Utilities Ping – tests connectivity between 2 hosts
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

31. Ping 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.
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.

32. Traceroute
Traceroute displays the path that a packet takes from the source to the destination host.
Each router that the packet passes through is called a hop
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.
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

33. Network Testing

34. 1.3: ISP Connectivity
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.

35. ISP Devices
Some of the devices required for an ISP to provide services include:
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

36. ISP Devices

37. ISP Growth Requirements
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

38. Scalability
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.
Modules can have different numbers of ports and allow for different connection types

39. ISP Roles
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.

40. ISP Roles Roles and responsibilities within an ISP:
On-site Installation
Customer Service
Planning and Provisioning
Identifies whether existing network and hardware and circuits are available
NOC (network operations center)
monitoring & testing
Help Desk