TCP/IP 3-way Handshake

This slide gives you the complete overview of TCP/IP 3-way handshaking. How it works?

1. TCP 3-way Handshake Process Submitted To:- Mrs. Rashmi Trivedi Sharma Submitted By :- Aditya Raj Amit Singh Rawat Alok Kumar Tripathi

2. Agenda Introduction to TCP/IP. Features of TCP/IP. Merits & Demerits of TCP/IP Connection Establishment and Termination. 3-Way Handshake Process.

3. Introduction to TCP/IP. The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly referred to as TCP/IP. TCP provides reliable, ordered, and error-checked delivery of a stream of octets (bytes) between applications running on hosts communicating by an IP network. Transmission Control Protocol/Internet Protocol (TCP/IP) is the language a computer uses to access the internet. It consists of a suite of protocols designed to establish a network of networks to provide a host with access to the internet. TCP/IP is responsible for full-fledged data connectivity and transmitting the data end to end by providing other functions, including addressing, mapping and acknowledgment. TCP/IP contains four layers, which differ slightly from the OSI model.

4. TCP/IP Model Protocols

5. Description of different TCP/IP protocols Layer 1: Host-to-network Layer Lowest layer of the all. Protocol is used to connect to the host, so that the packets can be sent over it. Varies from host to host and network to network. Layer 2: Internet layer Selection of a packet switching network which is based on a connectionless internetwork layer is called a internet layer. It is the layer which holds the whole architecture together. It helps the packet to travel independently to the destination. Order in which packets are received is different from the way they are sent. IP (Internet Protocol) is used in this layer. cont...

6. 6. The various functions performed by the Internet Layer are: Delivering IP packets Performing routing Avoiding congestion Layer 3: Transport Layer It decides if data transmission should be on parallel path or single path. Functions such as multiplexing, segmenting or splitting on the data is done by transport layer. The applications can read and write to the transport layer. Transport layer adds header information to the data. Transport layer breaks the message (data) into small units so that they are handled more efficiently by the network layer . Transport layer also arrange the packets to be sent, in sequence. cont...

7. Layer 4: Application Layer The TCP/IP specifications described a lot of applications that were at the top of the protocol stack. Some of them were TELNET, FTP, SMTP, DNS etc. TELNET is a two-way communication protocol which allows connecting to a remote machine and run applications on it. FTP(File Transfer Protocol) is a protocol, that allows File transfer amongst computer users connected over a network. It is reliable, simple and efficient. SMTP(Simple Mail Transport Protocol) is a protocol, which is used to transport electronic mail between a source and destination, directed via a route. DNS(Domain Name Server) resolves an IP address into a textual address for Hosts connected over a network. It allows peer entities to carry conversation. It defines two end-to-end protocols: TCP and UDP. TCP(Transmission Control Protocol): It is a reliable connection-oriented protocol which handles byte-stream from source to destination without error and flow control. UDP(User-Datagram Protocol): It is an unreliable connection-less protocol that do not want TCPs, sequencing and flow control. Eg: One-shot request-reply kind of service. cont...

8. Merits of TCP/IP model It operated independently. It is scalable. Client/server architecture. Supports a number of routing protocols. Can be used to establish a connection between two computers. Demerits of TCP/IP In this, the transport layer does not guarantee delivery of packets. The model cannot be used in any other application. Replacing protocol is not easy. It has not clearly separated its services, interfaces and protocols. Merits & Demerits of TCP/IP

9. Connection Establishment Establishes a virtual path between the source and destination. How TCP is connection-oriented while using IP (connection-less)? Connection is virtual. TCP uses the services of IP to deliver individual segments, but it controls the connection itself. IP is unaware of retransmission, out-of-order segments cont...

10. Client Server SYN SYN+ACK ACK cont...

11. It is for synchronization of sequence numbers. It consumes 1 sequence number. Carries no real data . SYN : SYN+ACK: ACK : SYN segment for communication in other direction and ACK for the received SYN . It consumes 1 sequence number. Just an ACK segment. Does not consume any sequence number.

12. Connection Termination Client Server FIN FIN +ACK ACK cont...

13. It consumes 1 sequence number May or may not carry real data. FIN : FIN +ACK: ACK: FIN segment to announce closing of connection in other direction and ACK for the received FIN. It consumes 1 sequence number. Just an ACK segment. Does not consume any sequence number.

14. 3-way Handshake Process cont...

15. A three-way handshake is a method used in a TCP/IP network to create a connection between a local host/client and server. It is a three-step method that requires both the client and server to exchange SYN and ACK (acknowledgment) packets before actual data communication begins. A three-way handshake is also known as a TCP handshake.

16. Steps... Step 1. Device A (Client) sends a TCP segment with SYN = 1, ACK = 0, ISN (Initial Sequence Number) = 2000. The Active Open device (Device A) sends a segment with the SYN flag set to 1, ACK flag set to 0 and an Initial Sequence Number 2000 (For Example), which marks the beginning of the sequence numbers for data that device A will transmit. SYN is short for SYNchronize. SYN flag announces an attempt to open a connection. The first byte transmitted to Device B will have the sequence number ISN+1. cont...

17. Step 2. Device B (Server) receives Device A’s TCP segment and returns a TCP segment with SYN = 1, ACK = 1, ISN = 5000 (Device B’s Initial Sequence Number), Acknowledgment Number = 2001 (2000 + 1, the next sequence number Device B expecting from Device A). Step 3. Device A sends a TCP segment to Device B that acknowledges receipt of Device B’s ISN, With flags set as SYN = 0, ACK = 1, Sequence number = 2001, Acknowledgment number = 5001 (5000 + 1, the next sequence number Device A expecting from Device B) This handshaking technique is referred to as the Three-way handshake or SYN, SYN-ACK, ACK. cont...

18. Step 1 (SYN) : In the first step, client wants to establish a connection with server, so it sends a segment with SYN(Synchronize Sequence Number) which informs server that client is likely to start communication and with what sequence number it starts segments with. Step 2 (SYN + ACK): Server responds to the client request with SYN-ACK signal bits set. Acknowledgement(ACK) signifies the response of segment it received and SYN signifies with what sequence number it is likely to start the segments with Step 3 (ACK) : In the final part client acknowledges the response of server and they both establish a reliable connection with which they will start eh actual data transfer cont... In Sort ... cont...