The document provides a detailed overview of ISP architecture and components. It discusses that an ISP uses various technologies like fiber optics, satellite, copper wire to provide internet access to customers. The key components of an ISP architecture include modems, remote access server, SMTP server, router, web server. It then describes different types of internet access provided by ISPs like dial-up, DSL, cable, wireless broadband, Wi-Fi, ISDN, and Ethernet. It concludes by explaining the basic process of how an ISP works to provide internet access by checking for static/dynamic IP addresses and routing data requests between the user and destination servers.

1. ASSIGNMENT NO 4
SUBMITTED TO:
MAM SARA SERWER
SUBMITTED BY:
AQSA REHMAN
ROLL NO:
17581556-023
IAP BSIT 5TH
A

2. Q1:Explore the complete ISP Architecture and Components in detail.
ANS: ISP:
An Internet Service Provider (ISP) is a company such as AT&T, Verizon, Comcast, or
BrightHouse that provides Internet access to companies, families, and even mobile
users. ISPs use fiber-optics, satellite, copper wire, and other forms to provide Internet access to
its customers.
ISP Architecture:
An ISP architect defines the overall structure, called the architecture, that sets forth
structuring principles and patterns for an ISP's infrastructure, services, network, customer care
system, and so on.
It consists of set of modems, remote access server, SMTP server, router, web server.
Set of Modems:
Convert analog signal into digital signals. Connects ISP to subscriber.
A modem is a device that provides access to the Internet (see below). The modem connects to
your ISP, which typically provides either cable or DSL Internet service. Cable modems have a

3. coaxial (or "coax") connection, which is the same type of connector found on a TV or cable box.
... ISP. Internet.
Remote access server:
All subscriber are connect to RAS through modems.
It maintains database of valid user and password.
It also verifies id and password.
SMTP:
SMTP is an acronym for Simple Mail Transfer Protocol. Majority of internet providers
novadays, use this protocol to send email. When using SMTP, there should be a client sending
the messages and the server receiving them.
Web Server:
The user can create their own web pages. To provide value services.
Such as
News update
Whether forecasting etc
Routers:
It maintains routing table.
Subscriber maybe connect to isp through routers’.
Components of ISP:
Dial-up Internet access
This is the oldest method of providing access to the Internet. It uses a telephone line to perform a
modem-to-modem connection. For that purpose, the user's computer is attached to a telephone
line enabled modem device, which dials into the node of the ISP and starts transferring data
between the servers that store websites the user wants to see and their Internet connected device.
The dial-up Internet is today considered outdated in most Internet societies due to the slow
connection speed it ensures (about 40-50 kbit/s.). However, the wide availability of telephone
access makes this type of Internet access the only alternative for remote areas that remain off the

4. broadband network. It is also the least expensive Internet access service and is preferred by users
on a tight budget.
DSL
DSL, short for 'digital subscriber loop' or 'digital subscriber line', is an advanced version of the
dial-up Internet access method. In contrast to dial-up, DSL uses high frequency to execute a
connection over the local telephone network. This allows the Internet and the phone connections
to be run on one and the same telephone line. The digital subscriber line technology ensures an
Asymmetric Digital Subscriber Line (ADSL), where the upload speed is lower than the
download speed, and a Symmetric Digital Subscriber Line (SDSL), offering equal upload and
download speeds. Of them both, ADSL is much more popular and is even known as just DSL to
users.
Cable Internet
The cable Internet is among the most preferred methods for providing residential Internet access.
Technically speaking, it represents a broadband Internet access method, using the high-
bandwidth cable television network to transmit data between the global network and the
households. To use cable Internet you will need a cable modem at home that will be connected
with the CMTS (Cable Modem Termination System) of your cable ISP. The cable Internet
access can be offered together with a cable television subscription and separately, for customers'
convenience. The second case incurs higher subscription fees due to the extra equipment
installation costs.
Wireless Broadband (WiBB)
This is a new-generation broadband Internet access technology, allowing the delivery of high-
speed wireless Internet within a large area. Wireless broadband ISPs (WISPs) ensure connection
speeds that come close to the wired broadband speeds provided by DSL and cable ISPs. To get
wireless broadband you need to place a specific dish on your house roof or apartment balcony
and point it to the transmitter of your WISP. This type of Internet access is used as an alternative
to the wired broadband connection in remote areas.
Wi-Fi Internet
Wi-Fi (from Wireless Fidelity) has become one of the most widely distributed Internet access
methods, with the growing usage of portable computers and Internet enabled mobile devices,
such as smart phones, PDAs, game consoles, etc. In this sense, it is the most mobile Internet
access method, since you are able to use it everywhere as long as you are located within the
scope of coverage, i.e. within the range of an Internet connected wireless network. Due to its
ability to serve mobile devices, Wi-Fi is used in public places such as airports, hotels and
restaurants to provide Internet access to customers. There are also specialized Wi-Fi hotspots
where the service is either free or paid. Some of the largest cities in the world are in the process
of building Wi-Fi networks that cover all the public places in the central areas.

5. ISDN
Another online data transmission method worth considering is ISDN or the Integrated Services
Digital Network. ISDN represents a telephone system network, integrating a high-quality digital
transmission of voice and data over the ordinary phone line. Ensuring a much better data
transmission over the phone line than an analog line could allow, the ISDN offers a fast
upstream/downstream Internet connection speed of 128 kbit/s. This speed level can be
considered as a broadband speed as opposed to the narrowband speed of standard analog 56k
telephone lines.
Ethernet
Another Internet access type worth mentioning is Ethernet - the most widespread wired LAN
(local area network) technology, also used in wireless LANs. The Ethernet technology may
ensure various speed levels and can thus be divided into several types: regular Ethernet,
providing transmission speeds of up to 10 mbits/s, fast Ethernet, offering up to 100 mbits/s,
gigabit Ethernet, supporting 1 gbit/s and 10-Gbit Ethernet, coming at up to 10 gbits/s.
How does an ISP Work?
Connect your computer to the network with the modem/router.
1- Modem sends request to the ISP.
2- ISP checks whether you have a static IP address.
3- If YES, your request is processed. OR If NO, the ISP communicates with the DHCP
server and allots your computer a dynamic IP address.
4- Your request is processed by the ISP, the ISP figures out the IP address of the page that
you are requesting.
5- Once it knows the IP address of the requested page, it refers to its own cache.
6- If the page is available in its cache, it transfers the data from that page to your IP
address.
7- If the page is not available in its cache, then it tracks the IP address that you have
requested, and sends a request to that IP address.
8- If the server accepts the request, it allows data transfer to the ISP. OR If the request is
declined, you have to try again till it is accepted.
9- Once the request is accepted by the server, the data is sent to the ISP.
10- The ISP then redirects this data to your IP address.
11- You now have the data on your computer.