TCP/IP

Transmission control Protocol/Internet protocol

TCP/IP suite

• TCP/IP is part of a larger protocol suite.• IP suit most used and most proven suite in the

world• Contains specifications for email, ftp, and

terminal emulation.• TCP/IP transport and network layer of OSI

model but is based on it’s own 5 layer protocol (simplified OSI)

OSI to IP suite relation

Copyright, Cisco system

Transmission Control

• Layer 4 on TCP/IP model– Directly under application layer.– Combination of Presentation, session, and

transmission layers.

• Data unstructured stream of bytes• Main purpose is error checking and flow

control

Transmission Control

• TCP segmented into Header and Data section• Uses Ports to identify Source and destination

(16 bit number)• Data belonging to specific TCP connections are

identified by sockets– Combination of source and destination host

address and port– Allows servers to provide multiple services to

multiple clients.

Flow Control and Error checking

• Sending Node– Sequence of numbers and Acknowledgement

messages– Delivery information for destination

• Retransmission of data if data loss occurs• Drops duplicate data• Slows transmission if destination computer is

behind

Internet Protocol

• Heart of the TCP/IP suite• Primary Layer 3 protocol• Packet-switching (apposed to circuit

switching)• Error reporting• Fragmentation and reassembly of Datagrams

– Data larger than MTU (max transmission unit) is fragmented by IP.

Internet Protocol• Data encapsulation (fragmentation) allows

packets to travel over any type of network with no concern for Higher layer operations.– Email and ftp can travel over the same or separate

networks. • IP does not account for data error

– Best effort delivery – No guarantees that data will arrive at destination– Up to TCP to ensure data transmission

• Does ensure reassembled fragments are in order.• Does error check it’s IP header.

IP Address

• Globally unique• 3 classes, A, B, and C• Divided into 3 parts, Network, subnet, host

address• Allow IP networks to communicate with each

other across the world• Networks can be subdivided further with a

subnet mask

IP address

Copyright, Cisco system

IP address Classes

• Class A for Large networks– 8 bits for network section

• Class B 16 bits for network• Class C 24 bits for network leaving 8 bits for

Hosts• Leftmost bits indicate Class

Why?

• Internet– TCP/IP is why the internet works– Interconnecting networks– Allows for any network to communicate with

another

• TCP/IP allows data to move through separate networks until it reaches it’s destination through routing.

Internet

Copyright, Cisco system

Internet

Wikipededia