TCP/IP have 5 layers, whereas OSI model have 7 layers in its Model. TCP/IP is known for the secured connection and comunication. I have explained all functions and definitions of layers in TCP/IP Model

1. Shubham KhedekarShubham Khedekar

2. Introduction TCP/IPIntroduction TCP/IP
 The Internet Protocol Suite (commonly known
as TCP/IP) is the set of communications
protocols used for the Internet and other similar
networks.
 It is named from two of the most important protocols
in it:
 Transmission Control Protocol (TCP) and
 Internet Protocol (IP), which were the first two
networking protocols defined in this standard.

4. APPLICATION LAYER
 This layer is comparable to the application,
presentation, and session layers of the OSI model all
combined into one.
 It provides a way for applications to have access to
networked services.
 It is widely-known layer for the exchange of user
information

5.  The Hypertext Transfer Protocol (HTTP) is used to
transfer files that make up the Web pages of the
World Wide Web.
 The File Transfer Protocol (FTP) is used for
interactive file transfer.
 The Simple Mail Transfer Protocol (SMTP) is used
for the transfer of mail messages and attachments.

6.  Presentation Layer does Encryption-Decryption and
Compression-Decompression of Data.
 This layer allows a process to add checkpoints which
are considered as synchronization points into stream of
data.

8. TRANSPORT LAYER
 This layer acts as the delivery service used by the
application layer.
 Two protocols used are TCP and UDP.
 The choice is made based on the application's
transmission reliability requirements.
 The transport layer also handles all error detection
and recovery.

9.  It uses checksums, acknowledgements, and timeouts
to control transmissions and end to end verification.
 Unlike the OSI model, TCP/IP treats reliability as an
end-to-end problem
 TCP provides a one-to-one, connection-oriented,
reliable communications service.
 UDP provides a one-to-one or one-to-many,
connectionless, unreliable communications service.

10.  A message is divided into segments; each segment
contains sequence number, which enables this layer
in reassembling the message.

11.  Message is reassembled correctly upon arrival at the
destination and replaces packets which were lost in
transmission.
 Connection Control : It includes 2 types :
1. Connectionless Transport Layer : Each segment is
considered as an independent packet and delivered
to the transport layer at the destination machine.
2. Connection Oriented Transport Layer : Before
delivering packets, connection is made with
transport layer at the destination machine.

12. NETWORK LAYER
 This layer is also known as Internet Layer. The main
purpose of this layer is to organize or handle the
movement of data on network.
 By movement of data, we generally mean routing of
data over the network.
 This layer is responsible for addressing, packaging,
and routing functions.

13.  The core protocols of the Internet layer are IP, ARP,
ICMP, and IGMP.
 The Internet Protocol (IP) is a routable protocol
responsible for IP addressing, routing, and the
fragmentation and reassembly of packets.
 The Address Resolution Protocol (ARP) is
responsible for the resolution of the Internet layer
address to the Network Interface layer address such
as a hardware address.

14.  The Internet Control Message Protocol (ICMP) is
responsible for providing diagnostic functions and
reporting errors due to the unsuccessful delivery of IP
packets.
 The Internet Group Management Protocol (IGMP) is
responsible for the management of IP multicast
groups.

15.  It translates logical network address into physical
address. Concerned with circuit, message or packet
switching.
 Routers and gateways operate in the network layer.

17. DATA LINK LAYER
 Data link layer is most reliable node to node delivery
of data.
 It forms frames from the packets that are received
from network layer and gives it to physical layer.
 It also synchronizes the information which is to be
transmitted over the data. Error controlling is easily
done.

18.  Protocols of this layer determine which of the devices
has control over the link at any given time, when two
or more devices are connected to the same link.

19.  Error control is achieved by adding a trailer at the end
of the frame.
 Duplication of frames are also prevented by using this
mechanism.
 Frames are the streams of bits received from the
network layer into manageable data units.
 This division of stream of bits is done by Data Link
Layer.

20.  Switch and Bridge are used in this layer

21. PHYSICAL LAYER
 Physical layer is the lowest layer of all. It is
responsible for sending bits from one computer to
another.
 This layer is not concerned with the meaning of the
bits and deals with the physical connection
 This layer defines electrical and physical details
represented as 0 or a 1.

22.  This layer defines the rate of transmission which is
the number of bits per second.
 It deals with the synchronization of the transmitter
and receiver. The sender and receiver are
synchronized at bit level.
 Devices must be connected using the following
topologies: Mesh, Star, Ring and Bus.

23.  Physical Layer defines the direction of transmission
between two devices: Simplex, Half Duplex, Full
Duplex

24.  Deals with baseband and broadband transmission.
 Hubs and Repeater are used in this layer