Features of tcp (part 2) .68
- 1. Sub-Topic : Features of TCP (Part-2) 1
- 2. Recap In the previous topic , you have learnt about • Layers of TCP/IP protocol • Role of transport layer in TCP/IP protocol 2
- 3. Objectives On completion of this topic, you would be able to know about • List out the features supported by TCP • Understand features of TCP 3
- 4. TCP - Features • Numbering System • Byte Number • Sequence Number • Acknowledgement Number • Reliable transfer of data • Flow Control • Error Control • Congestion Control 4
- 5. TCP – Features ( Contd…) • Inter-operability • Flexibility • Multi-Vendor Support • Window Based Protocol • Connection oriented service • Full duplex data transfer 5
- 6. TCP – Numbering System • TCP keeps track of the segments being transmitted or received by assigning numbers • Byte Number assigned to data bytes to be transferred • Sequence Number to Segments • Acknowledgement Number to Received segments 6
- 7. Byte Number • Used for Flow Control and Error Control • All data bytes transmitted in each connection are numbered by the TCP • Numbering starts with a randomly generated number • Numbering is independent in each direction • TCP stores the received data bytes in a sending buffer and numbers them 7
- 8. Sequence Number • TCP assigns a Sequence number to each segment transmitted • Sequence Number is the first byte number carried in that segment Sequence Number is assigned when • Segment carries both data and control information ( Piggy backing ) • Segment without data, no sequence number • Example : if x Sequence Number x+1 First Byte Number 8
- 9. Acknowledgement Number • Indicates number of the next byte that the receiver expects to receive • Acknowledgement number is cumulative • Confirmation to received data bytes 9
- 10. TCP – Reliable Transfer of Data • Ordered data transfer - the destination host rearranges according to sequence number • Retransmission of lost packets - any cumulative stream not acknowledged will be retransmitted • Discarding duplicate packets • Error-free data transfer 10
- 11. TCP – Reliable Transfer of Data Client Host Send Packet 1 Start Timer Data Packet Packet should arrive Timer ACK should be sent ACK would normally Arrive at this time Time Expires Retransmit Packet1 Timer Start Timer Receive Packet 1 Send ACK 1 Receive ACK 1 Cancel Timer Fig.4 11
- 12. TCP – Flow Control • limits the rate a sender transfers data to guarantee reliable delivery • The receiver continually hints the sender on how much data can be received (controlled by the sliding window) • When the receiving host's buffer fills, the next acknowledgment contains a 0 in the window size, to stop transfer and allow the data in the buffer to be processed 12
- 13. TCP – Error Control • TCP implements an error control mechanism for reliable data transfer • Error Control is byte – oriented • Segments are checked for error detection • Error Control includes detecting • Corrupted Segments and Lost Segments • Out-of-Order Segments • Duplicated Segments 13
- 14. TCP – Error Control • Error detection & Correction is achieved by – Check Sum – Acknowledgement Numbers – Time-outs 14
- 15. TCP – Congestion Control • TCP takes in to account the level of Congestion in the network • Congestion level determines the amount of data sent by a sender 15
- 16. TCP - Interoperability • TCP has become the Industry standard • It supports interoperability across networks • TCP – A frame work used to develop • complete range of computer communication standards 16
- 17. TCP – Flexibility • TCP allows a variety of implementations Multi-Vendor Support • TCP is supported by almost all network software • Widely used transport layer protocol 17
- 18. Summary In this class, you have learnt about • TCP is a widely used transport layer protocol • TCP provides process to process, full duplex and connection oriented services • The main features supported by TCP are • Segment Numbering System • Flow Control • Error Control • Congestion Control 18
- 19. Summary In this topic, you have learnt about • Basic unit of data transfer using TCP is Segment • TCP uses flow control implemented as a sliding window mechanism • Data bytes being transferred in each connection are numbered by TCP • Numbering starts with a randomly generated number 19
- 20. Summary TCP uses error control to provide reliable service. Error Control is handled by • checksum, acknowledgement and time-outs • Duplicated segments are discarded and Corrupted & lost segments are retransmitted • Data arrived out of order are temporarily stored by receiving TCP • TCP guarantees that no out of order segment is delivered to the process 20
- 21. Quiz 1. TCP is a ____________ layer protocol A. Application B. Transport C. Network D. Physical 21
- 22. Quiz 2. Which of the following features are supported by TCP ? A. Congestion Control B. Error Control C. Flow Control D. All The Above 22
- 23. Frequently Asked Questions 1. Name the protocols used in the Transport Layer of the TCP/IP protocol suite 2. What is the purpose of TCP ? 3. List the features of TCP 4. Explain about the various features supported by TCP 23
- 24. 3.24 DIFFERENT LAYERS OF TCP/IP 9EC606A.68 24