The document discusses the architecture and workings of the Internet. It provides definitions and explanations of key concepts: - The Internet is a network of networks that connects millions of devices globally using standardized communication protocols like TCP/IP. There is no single entity that controls it. - Individual networks are connected through routers that pass traffic between them. Routers know the addresses of local networks and pass packets to the appropriate outgoing link. - IP addresses identify devices and allow location addressing. The IP layer handles packaging, addressing, and routing of data packets across the networks. - Other important concepts discussed include protocols like TCP and UDP, the OSI model layers, DNS lookups, firewalls, and differences between internet, intr

1. Internet
Architecture

2. Fortunately, nobody owns the Internet, there is no
centralized control, and nobody can turn it off. Its evolution
depends on rough consensus about technical proposals, and
on running code. Engineering feed-back from real
implementations is more important than any architectural
principles.

3. Internet
The Internet is a worldwide, publicly accessible network of
interconnected computer networks that transmit data by
packet switching using the standard Internet Protocol (IP).
It is a "network of networks" A better way for us to start
visualizing the Internet is as an opaque cloud to which
hosts connect.
The power of the Internet is from respecting the end-to-end
principle.

4. What is the Internet architecture?
It is by definition a meta-network, a constantly changing
collection of thousands of individual networks
intercommunicating with a common protocol.
A short form of the compound word "inter-networking".
This architecture is based in the very specification of the
standard TCP/IP protocol, designed to connect any two
networks which may be very different in internal hardware,
software, and technical design.

5. Internet Path
An individual's access to the Internet is often from home
over a modem to a local Internet service provider who
connects to a regional network connected to a national
network.
Individual Modem(router) Local internet network
National Network Regional Network

6. Data Communication
• Data Communication means the exchange of between
two or more devices via some transmission medium.
• Main components of data communication
Sender Receiver
Station 1 Station 2
Protocol
Rules
------
------
--
Transmission
Medium (Cable wire,
Fibre Optics, etc.)

7. Network Topology

8. Protocols
– End systems, routers, and other pieces of the Internet, run
protocols that control the sending and receiving of information
within the Internet.
– TCP (Transmission Control Protocol) and IP (Internet protocol)
are two of the most important protocols in the Internet.
– The Internet’s principal protocols are collectively known as
TCP/IP Protocol Suite.
Hi
Hi
Got the
time?
2:00
TCP connection
req
TCP connection
response
<file>
time

9. OSI layer Model
7 Layers
7. Application Layer - Cables
6. Presentation Layer - Ethernet
5. Session Layer - IP
4. Transport Layer – TCP/UDP
3. Network Layer
2. Data Link Layer
1. Physical Layer
All
People
Seem
To
Need
Data
Processing

10. TCIP/IP Model
4 Layers
4. Application Layer
FTTP, HTTP,….
3. Transport Layer
TCP, VDP, SCTP
2. Internet Layer
ARP, RARP, ICMP, IGMP
1. Network Interface layer

11. Internet Layer
• Packaging
• Addressing
• Routing

12. IP Address
• 4 bytes
– e.g. 163.1.125.98
– Each device normally gets one (or more)
– In theory there are about 4 billion available
An IP address serves two principal functions: host or
network interface identification and
location addressing.

13. Routing
• How does a device know where to send a packet?
– All devices need to know what IP addresses are on directly
attached networks
– If the destination is on a local network, send it directly there
• If the destination address isn’t local
– Most non-router devices just send everything to a single local
router
A router receives chunk of information from one of its
incoming communication link and forwards it to one
of its outgoing communication link.

14. Continue…
• Routers (nodes) are devices on multiple networks that
pass traffic between them
• Individual networks pass traffic from one router or
endpoint to another
• Responsible for end to end transmission
• Sends data in individual packets
• Maximum size of packet is determined by the networks

15. Terms to familiarize
• Domain name
• DNS Lookup
• Reverse DNS Lookup
• DNS Server
• HTTP

16. Interaction with Internet
• Suppose you type
http://www.flipkart.com

17. Working
Flipkart.com
DNS Lookup DNS Server
Destination

18. Firewall
• A choke point of control and monitoring
• Interconnects networks with differing trust
• Imposes restrictions on network services
– only authorized traffic is allowed
• Auditing and controlling access
– can implement alarms for abnormal behavior
• Itself immune to penetration
• Provides perimeter defence

19. Food for thought!
Internet vs. internet
Difference between:
internet, intranet and extranet
LAN vs. WAN
Why Circuit Switching is not appropriate for
data traffic?

20. Thank You
By:
Md. Zeeshan
Naman Rastogi