The Transport Layer
اسلاید 1: The Transport LayerChapter 6
اسلاید 2: The Transport ServiceServices Provided to the Upper LayersTransport Service PrimitivesBerkeley SocketsAn Example of Socket Programming: An Internet File Server
اسلاید 3: Services Provided to the Upper LayersThe network, transport, and application layers.
اسلاید 4: Transport Service PrimitivesThe primitives for a simple transport service.
اسلاید 5: Transport Service Primitives (2)The nesting of TPDUs, packets, and frames.
اسلاید 6: Transport Service Primitives (3)A state diagram for a simple connection management scheme. Transitions labeled in italics are caused by packet arrivals. The solid lines show the clients state sequence. The dashed lines show the servers state sequence.
اسلاید 7: Berkeley SocketsThe socket primitives for TCP.
اسلاید 8: Socket Programming Example: Internet File ServerClient code using sockets.6-6-1
اسلاید 9: Socket Programming Example: Internet File Server (2)Client code using sockets.
اسلاید 10: Elements of Transport ProtocolsAddressingConnection EstablishmentConnection ReleaseFlow Control and BufferingMultiplexingCrash Recovery
اسلاید 11: Transport Protocol(a) Environment of the data link layer.(b) Environment of the transport layer.
اسلاید 12: AddressingTSAPs, NSAPs and transport connections.
اسلاید 13: Connection EstablishmentHow a user process in host 1 establishes a connection with a time-of-day server in host 2.
اسلاید 14: Connection Establishment (2)(a) TPDUs may not enter the forbidden region.(b) The resynchronization problem.
اسلاید 15: Connection Establishment (3)Three protocol scenarios for establishing a connection using a three-way handshake. CR denotes CONNECTION REQUEST. (a) Normal operation, (b) Old CONNECTION REQUEST appearing out of nowhere. (c) Duplicate CONNECTION REQUEST and duplicate ACK.
اسلاید 16: Connection ReleaseAbrupt disconnection with loss of data.
اسلاید 17: Connection Release (2)The two-army problem.
اسلاید 18: Connection Release (3)Four protocol scenarios for releasing a connection. (a) Normal case of a three-way handshake. (b) final ACK lost.6-14, a, b
اسلاید 19: Connection Release (4)(c) Response lost. (d) Response lost and subsequent DRs lost.6-14, c,d
اسلاید 20: Flow Control and Buffering(a) Chained fixed-size buffers. (b) Chained variable-sized buffers. (c) One large circular buffer per connection.
اسلاید 21: Flow Control and Buffering (2)Dynamic buffer allocation. The arrows show the direction of transmission. An ellipsis (…) indicates a lost TPDU.
اسلاید 22: Multiplexing(a) Upward multiplexing. (b) Downward multiplexing.
اسلاید 23: Crash RecoveryDifferent combinations of client and server strategy.
اسلاید 24: A Simple Transport ProtocolThe Example Service PrimitivesThe Example Transport EntityThe Example as a Finite State Machine
اسلاید 25: The Example Transport EntityThe network layer packets used in our example.
اسلاید 26: The Example Transport Entity (2)Each connection is in one of seven states:Idle – Connection not established yet.Waiting – CONNECT has been executed, CALL REQUEST sent.Queued – A CALL REQUEST has arrived; no LISTEN yet.Established – The connection has been established.Sending – The user is waiting for permission to send a packet.Receiving – A RECEIVE has been done.DISCONNECTING – a DISCONNECT has been done locally.
اسلاید 27: The Example Transport Entity (3)
اسلاید 28: The Example Transport Entity (4)
اسلاید 29: The Example Transport Entity (5)
اسلاید 30: The Example Transport Entity (6)
اسلاید 31: The Example Transport Entity (7)
اسلاید 32: The Example Transport Entity (8)
اسلاید 33: The Example Transport Entity (9)
اسلاید 34: The Example Transport Entity (10)
اسلاید 35: The Example as a Finite State MachineThe example protocol as a finite state machine. Each entry has an optional predicate, an optional action, and the new state. The tilde indicates that no major action is taken. An overbar above a predicate indicate the negation of the predicate. Blank entries correspond to impossible or invalid events.
اسلاید 36: The Example as a Finite State Machine (2)The example protocol in graphical form. Transitions that leave the connection state unchanged have been omitted for simplicity.
اسلاید 37: The Internet Transport Protocols: UDPIntroduction to UDPRemote Procedure CallThe Real-Time Transport Protocol
اسلاید 38: Introduction to UDPThe UDP header.
اسلاید 39: Remote Procedure CallSteps in making a remote procedure call. The stubs are shaded.
اسلاید 40: The Real-Time Transport Protocol(a) The position of RTP in the protocol stack. (b) Packet nesting.
اسلاید 41: The Real-Time Transport Protocol (2)The RTP header.
اسلاید 42: The Internet Transport Protocols: TCPIntroduction to TCPThe TCP Service ModelThe TCP ProtocolThe TCP Segment HeaderTCP Connection EstablishmentTCP Connection ReleaseTCP Connection Management ModelingTCP Transmission PolicyTCP Congestion ControlTCP Timer ManagementWireless TCP and UDPTransactional TCP
اسلاید 43: The TCP Service ModelSome assigned ports.PortProtocolUse21FTPFile transfer23TelnetRemote login25SMTPE-mail69TFTPTrivial File Transfer Protocol79FingerLookup info about a user80HTTPWorld Wide Web110POP-3Remote e-mail access119NNTPUSENET news
اسلاید 44: The TCP Service Model (2)(a) Four 512-byte segments sent as separate IP datagrams.(b) The 2048 bytes of data delivered to the application in a single READ CALL.
اسلاید 45: The TCP Segment HeaderTCP Header.
اسلاید 46: The TCP Segment Header (2)The pseudoheader included in the TCP checksum.
اسلاید 47: TCP Connection Establishment(a) TCP connection establishment in the normal case.(b) Call collision.6-31
اسلاید 48: TCP Connection Management ModelingThe states used in the TCP connection management finite state machine.
اسلاید 49: TCP Connection Management Modeling (2)TCP connection management finite state machine. The heavy solid line is the normal path for a client. The heavy dashed line is the normal path for a server. The light lines are unusual events. Each transition is labeled by the event causing it and the action resulting from it, separated by a slash.
اسلاید 50: TCP Transmission PolicyWindow management in TCP.
اسلاید 51: TCP Transmission Policy (2)Silly window syndrome.
اسلاید 52: TCP Congestion Control(a) A fast network feeding a low capacity receiver.(b) A slow network feeding a high-capacity receiver.
اسلاید 53: TCP Congestion Control (2)An example of the Internet congestion algorithm.
اسلاید 54: TCP Timer Management(a) Probability density of ACK arrival times in the data link layer. (b) Probability density of ACK arrival times for TCP.
اسلاید 55: Wireless TCP and UDPSplitting a TCP connection into two connections.
اسلاید 56: Transitional TCP(a) RPC using normal TPC.(b) RPC using T/TCP.
اسلاید 57: Performance IssuesPerformance Problems in Computer NetworksNetwork Performance MeasurementSystem Design for Better PerformanceFast TPDU ProcessingProtocols for Gigabit Networks
اسلاید 58: Performance Problems in Computer NetworksThe state of transmitting one megabit from San Diego to Boston(a) At t = 0, (b) After 500 μsec, (c) After 20 msec, (d) after 40 msec.
اسلاید 59: Network Performance MeasurementThe basic loop for improving network performance.Measure relevant network parameters, performance.Try to understand what is going on.Change one parameter.
اسلاید 60: System Design for Better PerformanceRules:CPU speed is more important than network speed.Reduce packet count to reduce software overhead.Minimize context switches.Minimize copying.You can buy more bandwidth but not lower delay.Avoiding congestion is better than recovering from it.Avoid timeouts.
اسلاید 61: System Design for Better Performance (2)Response as a function of load.
اسلاید 62: System Design for Better Performance (3)Four context switches to handle one packet with a user-space network manager.
اسلاید 63: Fast TPDU ProcessingThe fast path from sender to receiver is shown with a heavy line.The processing steps on this path are shaded.
اسلاید 64: Fast TPDU Processing (2)(a) TCP header. (b) IP header. In both cases, the shaded fields are taken from the prototype without change.
اسلاید 65: Fast TPDU Processing (3)A timing wheel.
اسلاید 66: Protocols for Gigabit NetworksTime to transfer and acknowledge a 1-megabit file over a 4000-km line.
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