Presentation is loading. Please wait.

Presentation is loading. Please wait.

Guide to TCP/IP, Third Edition Chapter 5: Transport Layer TCP/IP Protocols.

Similar presentations

Presentation on theme: "Guide to TCP/IP, Third Edition Chapter 5: Transport Layer TCP/IP Protocols."— Presentation transcript:

1 Guide to TCP/IP, Third Edition Chapter 5: Transport Layer TCP/IP Protocols

2 2 Objectives Understand the key features and functions of the User Datagram Protocol Explain the mechanisms that drive segmentation, reassembly, and retransmission for the Transmission Control Protocol Choose between using User Datagram Protocol and Transmission Control Protocol

3 Transport Layer TCP/IP Protocols3 UDP – A Connectionless Transport Layer Protocol Connectionless protocols –Provide the simplest kind of transport services UDP –Used by applications that contain their own connection oriented timeout values and retry counters –Runs up to 40 percent faster than TCP

4 Transport Layer TCP/IP Protocols4 UDP – A Connectionless Transport Layer Protocol (continued) Connectionless protocols handle the following kinds of tasks –Message checksum –Higher-layer protocol identification

5 Transport Layer TCP/IP Protocols5 Overview of UDP UDP limitations –No reliability mechanisms –No delivery guarantees –No connection handling –Identifies Application layer protocol conveyed –Checksum for entire message carried in UDP header –No buffering services –No segmentation

6 Transport Layer TCP/IP Protocols6 UDP Header Fields and Functions UDP header’s main function –To define the process or application that is using the IP and UDP Network and Transport layers UDP header fields –Source Port Number field –Destination Port Number field –Length field –Checksum field

7 Transport Layer TCP/IP Protocols7

8 8 UDP Header Fields and Functions (continued) Source Port Number field –Defines the application or process that sends the packet using the UDP header Well-known port numbers (0 Through 1023) –Assigned to core services that systems offer Registered port numbers (1024 Through 49151) –Assigned to industry applications and processes Dynamic ports –Used as temporary ports for specific communications while they are underway

9 Transport Layer TCP/IP Protocols9

10 10 UDP Header Fields and Functions (continued) Destination Port Number Field –Defines destination application or process that uses the IP and UDP headers Length field –Defines the length of the packet from the UDP header to the end of valid data Checksum field is optional

11 Transport Layer TCP/IP Protocols11 UDP Port Numbers and Processes UDP and TCP –Use port numbers to define the source and destination processes or applications By default –Windows 2000 and Windows XP support up to 5,000 ports

12 Transport Layer TCP/IP Protocols12

13 Transport Layer TCP/IP Protocols13

14 Transport Layer TCP/IP Protocols14 TCP – A Connection-Oriented Protocol Functions of connection-oriented protocols –Create a logical connection directly between two peers on an internetwork –Track the transfer of data and ensure it arrives successfully –Use sequence number tracking –Have a timeout mechanism –Have a retry mechanism

15 Transport Layer TCP/IP Protocols15 Overview of TCP TCP offers connection-oriented services with –Sequencing, error recovery –Sliding window mechanism TCP hosts –Create a virtual connection with each other using a handshake process TCP –Transfers data as a continuous stream of bytes Maximum TCP segment size is 65,495 bytes

16 Transport Layer TCP/IP Protocols16

17 Transport Layer TCP/IP Protocols17 TCP Startup Connection Process Begins with handshake between two hosts One host initiates the handshake to another host to –Ensure the destination host is available –Ensure the destination host is listening on the destination port number –Inform destination host of initiator’s sequence number

18 Transport Layer TCP/IP Protocols18

19 Transport Layer TCP/IP Protocols19

20 Transport Layer TCP/IP Protocols20

21 Transport Layer TCP/IP Protocols21

22 Transport Layer TCP/IP Protocols22

23 Transport Layer TCP/IP Protocols23 TCP Half-Open Connections Occur when the handshake process does not end successfully with a final ACK Half-open connection communication sequence occurs in the following order –SYN >>>>> –<<<<< ACK SYN

24 Transport Layer TCP/IP Protocols24 TCP Keep-Alive Process Can maintain connection when there is no data sent across the wire TCP keep-alives –Disabled by default on Windows 2000, Windows Server 2003, and Windows XP KeepAliveTime setting –Defines how long to wait before sending the first TCP keep-alive packet

25 Transport Layer TCP/IP Protocols25

26 Transport Layer TCP/IP Protocols26 TCP Connection Termination Requires four packets –Host 1 Sends a TCP packet with the FIN and ACK flags set –Host 2 Sends an ACK in response Then sends a TCP packet with FIN and ACK flags set –Host 1 Returns ACK response

27 Transport Layer TCP/IP Protocols27

28 Transport Layer TCP/IP Protocols28

29 Transport Layer TCP/IP Protocols29 TCP Sequence and Acknowledgment Process Guarantees that packets are ordered properly and protects against missing segments During handshake process –Each side of connection selects its own starting sequence number –Each side increments its sequence number value by the amount of data included in the outbound packet

30 Transport Layer TCP/IP Protocols30

31 Transport Layer TCP/IP Protocols31

32 Transport Layer TCP/IP Protocols32 TCP Error-Detection and Error- Recovery Process Retransmission timer –First error-detection and error-recovery mechanism –Retransmission timeout (RTO) Value specified by timer Retransmission operation increments –1st retransmit: RTO seconds –2nd retransmit: 2 x RTO seconds –3rd retransmit: 4 x RTO seconds –4th retransmit: 8 x RTO seconds –5th retransmit: 16 x RTO seconds

33 Transport Layer TCP/IP Protocols33 TCP Congestion Control Congestion –The overloading of the network or a receiver Overloading of the network –Occurs when there is too much data on the network medium Overloading a receiver –Occurs when the number of data bytes is greater than the advertised window Current window –Always the lesser of what the network and receiver can handle

34 Transport Layer TCP/IP Protocols34

35 Transport Layer TCP/IP Protocols35 TCP Congestion Control (continued) TCP has four defined congestion control mechanisms –Slow Start –Congestion Avoidance –Fast Retransmit –Fast Recovery

36 Transport Layer TCP/IP Protocols36

37 Transport Layer TCP/IP Protocols37

38 Transport Layer TCP/IP Protocols38 TCP Sliding Window Used to determine the amount of unacknowledged data that can go out on the wire from any sender Nagle algorithm –When small data segments are being sent, but not acknowledged, no other small segments can be sent Silly Window Syndrome (SWS) –Caused when enough data is sent to a TCP host to fill its receiver buffer –Puts receiver in a zero-window state

39 Transport Layer TCP/IP Protocols39 TCP Header Fields and Functions Source Port Number Field Destination Port Number Field Sequence Number Field Acknowledgment Number Field Header Length Field

40 Transport Layer TCP/IP Protocols40

41 Transport Layer TCP/IP Protocols41

42 Transport Layer TCP/IP Protocols42

43 Transport Layer TCP/IP Protocols43 TCP Header Fields and Functions (continued) Window Size Field TCP Checksum Field Urgent Pointer Field TCP Options Field(s)

44 Transport Layer TCP/IP Protocols44

45 Transport Layer TCP/IP Protocols45

46 Transport Layer TCP/IP Protocols46 Choosing Between TCP and UDP Because TCP is robust and reliable –It carries a lot of baggage, including Additional header fields Explicit meta-messages in the form of TCP messages For some lightweight services, such as Microsoft Messenger Service –TCP is overkill and UDP is used instead TCP –No longer as important as it once was because Long-haul and local area networks have significantly increased speed, capacity, and reliability

47 Transport Layer TCP/IP Protocols47 Summary Transport layer protocols come in two types –Connectionless and connection-oriented User Datagram Protocol –The connectionless protocol associated with TCP/IP protocol suite UDP header is short and simple, consisting of –A protocol identifier in the IP header –An optional checksum value –Source and destination port addresses

48 Transport Layer TCP/IP Protocols48 Summary (continued) Transmission Control Protocol –Heavyweight, connection-oriented protocol that helps name the TCP/IP protocol suite TCP header –Longer and more complex, –Includes a variety of flags, values, and message types

49 Transport Layer TCP/IP Protocols49 Summary (continued) Appropriate (and historical) uses for UDP –Concentrate on Application layer services that manage their own reliability and connections Appropriate (and historical) uses for TCP –Concentrate on providing reliable delivery of user services

Download ppt "Guide to TCP/IP, Third Edition Chapter 5: Transport Layer TCP/IP Protocols."

Similar presentations

Ads by Google