This document provides an overview of Internet service providers (ISPs), including their typical structure, types, connection options, and internal architecture. It explains that ISPs provide internet access to individuals and companies. It also describes the common components of an ISP's internal architecture, such as modems, remote access servers, SMTP and web servers, and routers.

1. Sub topic : Internal architecture of ISP
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2. Recap
In the previous class, you have learnt about
• ARPA Net (Advanced Research Project Agency Net)
• WWW (World Wide Web)
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3. OBJECTIVES
On completion of this period, you would be able to know
about
• ISP
• Typical ISPs
• Types of ISPs
• ISP connection options
• Internal Architecture of ISP
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4. Internet Service Provider
ISP is an Internet Service Provider that provides
• Internet access to the Individuals
• Internet access to the Companies
• Services such as web site building and virtual hosting
• It can also be called as a Internet Access Provider.
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5. Typical ISPs
• WorldNet
• AT & T
• IBM Global Network
• MCI
• Netcom
• UUNet etc
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6. Types of ISPs
Depending on the Range ISPs can be
• Local ISPs
• Regional ISPs
• National ISPs
• International ISPs
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7. ISP ISP ISP ISP
X X X X
Regional ISP ……. Regional ISP
X X
National ISP
Fig 1.Structure of a national ISP
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8. National ISP
National ISP x National ISP
NAP x
x
National ISP National ISP
Fig.2.Interconnection of national
ISPs
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9. ISP Connection Options
• Home user connection
• Business connection
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10. ISP
Typical Home user connections
• Dial-up
• DSL
• Broad band wireless access
• Cable Modem
• ISDN * 10

11. ISP
Typical Business connections
• DSL
• SHDSL
• Ethernet Technologies
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12. Fig.3.Internal Architecture of ISP
Remote SMTP
Set of access server
modems server
S
U
B
S
Internet
C
R
I
B
E
R Web Server
S
Router
Router
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13. ISP Architecture consists of
• Set of Modems
• Remote Access Server
• SMTP Server
• Web Server
• Routers * 13

14. Set of Modems
• Convert Analog signal on the line to the Digital
• Connect ISP to the Subscriber
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15. Remote Access Server
• All subscribers are connected to RAS through set of
modems
• Maintains database of valid user id and password
• It also verifies user id and password
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16. SMTP Server
• It is Simple Message Transfer Protocol
• It stores subscribers e-mails until the subscriber connects
to the internet
• It sends and receives mails on behalf of its subscriber
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17. Web Server
• Subscribers can create their own web pages
To provide value added services such as
• News update
• Weather information
• Technical updates
• Sports updates
• Chat facilities
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18. Routers
• It maintains routing tables
• Subscribers may be connected to the Internet
through Routers
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19. Summary
In this class, you have learnt about
• ISP (Internet Service Provider)
• ISP types
• Its Internal Architecture in detail
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20. Quiz
(1) The function of RAS is
(a) To Authenticate the subscriber
(b) To maintains database of valid users
(c) a&b both
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21. Frequently Asked Questions
(1) Define ISP
(2) Explain the Internal Architecture of ISP
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