W14-15L28-29 Process to Process Communication.ppt
- 1. Lecture Objectives Learn about the responsibilities of Transport Layer Process to Process Delivery Protocols of Transport Layer Working of UDP working of TCP Discussion about the Headers of UDP and TCP
- 2. Position of Transport Layer
- 3. The transport layer is responsible for process-to-process delivery. Note Note: :
- 4. Types of Data Deliveries
- 5. Port Numbers
- 6. IP addresses versus port numbers
- 7. IANA ranges
- 12. Error control
- 13. UDP is a connectionless, unreliable protocol that has no flow and error control. It uses port numbers to multiplex data from the application layer. Note Note: :
- 14. Well-known ports used by UDP Well-known ports used by UDP 9 Discard Discards any datagram that is received 11 Users Active users 13 Daytime Returns the date and the time 17 Quote Returns a quote of the day 19 Chargen Returns a string of characters 53 Nameserver Domain Name Service 67 Bootps Server port to download bootstrap information 68 Bootpc Client port to download bootstrap information 69 TFTP Trivial File Transfer Protocol 111 RPC Remote Procedure Call 123 NTP Network Time Protocol 161 SNMP Simple Network Management Protocol 162 SNMP Simple Network Management Protocol (trap)
- 16. The calculation of checksum and its inclusion in the user datagram are optional. Note Note: :
- 17. UDP is a convenient transport-layer protocol for applications that provide flow and error control. It is also used by multimedia applications. Note Note: :
- 18. TCP Services TCP Services Port Numbers Services Sequence Numbers Segments Connection Flow and Error Control
- 19. Table 22.2 Table 22.2 Well-known ports used by TCP Well-known ports used by TCP Port Protocol Description 7 Echo Echoes a received datagram back to the sender 9 Discard Discards any datagram that is received 11 Users Active users 13 Daytime Returns the date and the time 17 Quote Returns a quote of the day 19 Chargen Returns a string of characters 20 FTP, Data File Transfer Protocol (data connection) 21 FTP, Control File Transfer Protocol (control connection) 23 TELNET Terminal Network 25 SMTP Simple Mail Transfer Protocol 53 DNS Domain Name Server 67 BOOTP Bootstrap Protocol 79 Finger Finger 80 HTTP Hypertext Transfer Protocol 111 RPC Remote Procedure Call
- 20. Stream Delivery
- 21. Sending and Receiving Buffers
- 22. TCP Segments
- 23. Example 1 Example 1 Imagine a TCP connection is transferring a file of 6000 bytes. The first byte is numbered 10010. What are the sequence numbers for each segment if data are sent in five segments with the first four segments carrying 1000 bytes and the last segment carrying 2000 bytes? Solution Solution The following shows the sequence number for each segment: Segment 1 ==> sequence number: 10,010 (range: 10,010 to 11,009) Segment 2 ==> sequence number: 11,010 (range: 11,010 to 12,009) Segment 3 ==> sequence number: 12,010 (range: 12,010 to 13,009) Segment 4 ==> sequence number: 13,010 (range: 13,010 to 14,009) Segment 5 ==> sequence number: 14,010 (range: 14,010 to 16,009)
- 24. The bytes of data being transferred in each connection are numbered by TCP. The numbering starts with a randomly generated number. Note Note: :
- 25. The value of the sequence number field in a segment defines the number of the first data byte contained in that segment. Note Note: :
- 26. The value of the acknowledgment field in a segment defines the number of the next byte a party expects to receive. The acknowledgment number is cumulative. Note Note: :
- 28. Control Field
- 29. Description of flags in the control field Description of flags in the control field Flag Description URG The value of the urgent pointer field is valid. ACK The value of the acknowledgment field is valid. PSH Push the data. RST The connection must be reset. SYN Synchronize sequence numbers during connection. FIN Terminate the connection.
- 32. States for TCP States for TCP State Description CLOSED There is no connection. LISTEN The server is waiting for calls from the client. SYN-SENT A connection request is sent; waiting for acknowledgment. SYN-RCVD A connection request is received. ESTABLISHE D Connection is established. FIN-WAIT-1 The application has requested the closing of the connection. FIN-WAIT-2 The other side has accepted the closing of the connection. TIME-WAIT Waiting for retransmitted segments to die. CLOSE-WAIT The server is waiting for the application to close.
- 33. A sliding window is used to make transmission more efficient as well as to control the flow of data so that the destination does not become overwhelmed with data. TCP’s sliding windows are byte-oriented. Note Note: :
- 34. Sender Buffer
- 35. Receiver window
- 36. Sender buffer and sender window
- 37. Sliding the sender window
- 38. Expanding the sender window
- 39. Shrinking the sender window
- 40. In TCP, the sender window size is totally controlled by the receiver window value (the number of empty locations in the receiver buffer). However, the actual window size can be smaller if there is congestion in the network. Note Note: :
- 41. Some points about TCP’s sliding windows: Note Note: : The source does not have to send a full The source does not have to send a full window’s worth of data. window’s worth of data. The size of the window can be increased or The size of the window can be increased or decreased by the destination. decreased by the destination. The destination can send an acknowledgment at any time.
- 42. Lost segment