Internet Service
Providers (ISP)
HOW INTERNET SERVICE PROVIDERS WORK
What is the role of an (ISP)?
'An Internet Service Provider
(ISP) is a company that
provides a user with access
to the Internet, usually for a
fee.'
Internet Service Providers (ISP)
Networks
There are small, medium and
larger computer networks all
needing access to the Internet.
‘Business Network’
Local Area Network (LAN)
‘Home’
Internet Service Providers (ISP)
The Internet
Packets of data are transmitted over the Internet using
switched technology guided by the IP address of end
computer.
The Internet
‘Home
Computer’
21.34.129.86
‘Another
Computer’
Packet of
data’
Internet Service Providers (ISP)
28.203.156.94
Transmitting Data packets
Here is a more detailed arrangement of how data
packets are transmitted across a network.
Public
Telephone
Network
Modem
Modem Pool
21.34.129.86
ISP Port
Server
LAN
‘Another Computer’
28.203.156.94
Router
Router
Router
CSU / DSU
Internet Service Providers (ISP)
CSU / DSU
Router
ISP Backbone
‘Home Computer’
Internet Service Provider (ISP)
Small and large networks connect to an ISP via a point
of presence (POP).
•
•
•
Conventional Phone
Digital subscriber line
Cable Modem
POP
Point of Presence (POP)
Internet Service
Provider (ISP)
‘Home’
‘Home Network’
Internet Service Providers (ISP)
‘Business Network’
Network Access Point (NAP)
The ISP then connects to a Network Access Point via a
T3 line (night data speed through put)
T3 Line
•
•
•
Conventional Phone
Digital subscriber line
Cable Modem
POP
NAP
Internet Service
Provider (ISP)
T1 Line
Point of Presence (POP)
‘Home’
Internet Service
Provider (ISP)
Internet Service Providers (ISP)
‘Business
Network’
Internet Backbone
The data packets
(datagrams) are then
sent at high speed across
the Internet backbone.
•
•
•
Conventional Phone
Digital subscriber line
Cable Modem
Internet Backbone
T3 Line
POP
NAP
Internet Service
Provider (ISP)
T1 Line
Point of Presence (POP)
‘Home’
Internet Service
Provider (ISP)
Internet Service Providers (ISP)
‘Business
Network’
Internet Backbone
This is a simplified diagram of how different networks interface.
Local
ISP
Internet Service
Providers (ISP)
MAE
Metropolitan Exchange
(MAE) privately owned
‘Network
Access Points’
Local
ISP
Local
ISP
Regional
ISP
‘Local ISP’
NAP
Internet
Backbone
NAP
Regional
ISP
Local
ISP
Regional
ISP
NAP
Local
ISP
NAP
Regional
ISP
Local
ISP
‘Regional ISP’
Internet Service Providers (ISP)
Internet Backbone
A backbone is typically a fibre optic
trunk line (OC carrier) that can carry
data at high speed.
There are many companies that
operate their own high capacity
trunk lines (NSP), such as:
-
Internet Service
Providers (ISP)
IBM
UUNet
CerfNet
BBN
SprintNet
PSINet
Internet Service Providers (ISP)
MAE
Metropolitan Exchange
(MAE) privately owned
‘Network
Access Points’
NAP
NAP
Internet
Backbone
NAP
NAP
Following Data Packets
You can follow a datagram through all the different paths taken to
end up at the destination IP address.
In the windows command prompt tyle in, tracert www.bbc.co.uk
(or you can perform the following request online:
http://traceroute-online.com/
Internet Service Providers (ISP)