TCP/UDP 指導教授：吳坤熹 演講者：黃驛翔 Class ： IP Telephony

Outline Introduction Linking to Application Layer Packetization and Reassembly –Protocol Data Units –TCP Header –UDP Header Establishing connection (virtual) –TCP technique –UDP technique

Outline (Con.) Service Primitives TCP vs. UDP References

Introduction Transport layer –Responsible for end-to-end delivery of messages –Responsible for segmentation and reassembly Two Protocols ： –TCP (Transmission Control Protocol) –UDP (User Datagram Protocol)

Introduction Transport Layer Functions –Linking to Application Layer –Packetization and Reassembly –Establishing connection (virtual) Connect oriented Connectionless Quality of Service (QoS)

Linking to Application Layer TCP may serve several Application at the same time User identified by port number or service access point (SAP)

Packetization and Reassembly

Protocol Data Units (PDU) At each layer, protocols are used to communicate Control information is added to user data at each layer (PDU = Control + Data) Transport layer may fragment user data Each fragment has a transport header added –Destination SAP (port) –Sequence number –Error detection code

TCP Header

UDP Header

Establishing connection ─ TCP Connection-oriented –Establishment –Maintenance –Termination Reliability –Data confirm –Error correction Flow control

Connection-oriented - Establishment 3-Way Handshaking

Connection-oriented – Termination  Seq:X, ACK: Y. ACK..FIN  Seq:Y, ACK: X+1, ACK  Seq:Y, ACK: X+1, ACK..FIN  Seq:X+1, ACK: Y+1, ACK

Reliable – Data confirm

Reliable – Error correction

Flow control S liding Window

The usage of TCP ProtocolPort #Application UDP53DNS UDP67BOOTP server UDP68BOOTP client UDP520RIP TCP20FTP data TCP21FTP Control TCP23Telnet TCP25SMTP TCP80HTTP TCP119NNTP

Establishing connection ─ UDP Connection-less No acks (Unconfirmed Service) –high rate of transmission –But unreliable No flow control

Connection-less Sending packets individually without a virtual circuit Each packet is sent independently It will be routed separately, following different routes and arriving at different time

The consideration of using UDP Reduce the requirement of computer resources The checking scheme has provided completely by the application program When using the Multicast or Broadcast to transfer The transmission of Real-time packets

The usage of UDP Trivial File Transfer Protocol ， TFTP Simple Network Management Protocol ， SNMP Dynamic Host Configuration Protocol ， DHCP Domain Name System ， DNS Routing Information Protocol ， RIP Real-Time Transport Protocol ， RTP

Service Primitives Primitives specify function to be performed for the transport layer Four Primitive types Confirmed service ： TCP Nonconfirmed service ： UDP

Primitive Types REQUEST A primitive issued by a service user to invoke some service and to pass the parameters needed to specify fully the requested service INDICATION A primitive issued by a service provider either to: indicate that a procedure has been invoked by the peer service user on the connection and to provide the associated parameters, or notify the service user of a provider-initiated action RESPONSE A primitive issued by a service user to acknowledge or complete some procedure previously invoked by an indication to that user CONFIRM A primitive issued by a service provider to acknowledge or complete some procedure previously invoked by a request by the service user

Timing Sequence for Service Primitives

TCP vs. UDP TCP UDP connection-oriented connectionless confirmed service unconfirmed service (request, indication, (request, indication) response, confirm) high overhead low overhead (header 20 octets) (header 8 octets) flow control no flow control

References J. FitzGerald and A. Dennis, “Business Data Communications and Networking”, (9 th Ed. 2007), John Wiley & Sons Inc., U.S.A. J. F. Hurose and K. W. Ross, “computer Networking”, (4 th Ed. 2006), Peason Addison-Wesley Inc., U.S.A. 吳坤熹 教授， ”The PowerPoint of IP Telephony class”, 2008 陳彥錚 副教授， ” The PowerPoint of Computer Networking class, Ch2,Ch6”, 2008 William Stallings, Computer Networking with Internet Protocols and Technology, Prentice Hall, 2008