Connectionless demux:example DatagramSocket DatagramSocket serverSocket new DatagramSocket mySocket2 new DatagramSocket mySocketl new DatagramSocket (6428): DatagramSocket (9157): application (5775): application P1 application (P3 配 P4 transport nerwork transpor network ink k phs中 link physical phy师cal source port:6428 source port: dest port:9157 dest port: source port:9157 source port: dest port:6428 dest port: Transport Layer3-11
Transport Layer3-11 Connectionless demux: example DatagramSocket serverSocket = new DatagramSocket (6428); transport application physical link network P3 transport application physical link network P1 transport application physical link network P4 DatagramSocket mySocket1 = new DatagramSocket (5775); DatagramSocket mySocket2 = new DatagramSocket (9157); source port: 9157 dest port: 6428 source port: 6428 dest port: 9157 source port: ? dest port: ? source port: ? dest port: ?
Connection-oriented demux TCP socket identified server host may support by 4-tuple: many simultaneous TCP ·source IP address sockets: ·source port number each socket identified by ·dest IP address its own 4-tuple ·dest port number web servers have demux:receiver uses all different sockets for four values to direct each connecting client segment to appropriate non-persistent HTTP will socket have different socket for each request Transport Layer3-12
Transport Layer3-12 Connection-oriented demux ▪ TCP socket identified by 4-tuple: • source IP address • source port number • dest IP address • dest port number ▪ demux: receiver uses all four values to direct segment to appropriate socket ▪ server host may support many simultaneous TCP sockets: • each socket identified by its own 4-tuple ▪ web servers have different sockets for each connecting client • non-persistent HTTP will have different socket for each request
Connection-oriented demux:example application application P4 P5 P6 application (P3 P2 (P3 transport etwork transport netvork k network k hysical link physical server:IP physical address B host:IP source IPport:B,80 host:IP addressA dest IPport:A,9157 source IP,port:C,5775 address C dest IPport:B,80 source IPport:A,9157 dest IP,port:B,80 source IPport:C,9157 dest IP,port:B,80 three segments,all destined to IP address:B, dest port:80 are demultiplexed to different sockets Transport Layer3-13
Transport Layer3-13 Connection-oriented demux: example transport application physical link network P3 transport application physical link P4 transport application physical link network P2 source IP,port: A,9157 dest IP, port: B,80 source IP,port: B,80 dest IP,port: A,9157 host: IP address A host: IP address C network P5 P6 P3 source IP,port: C,5775 dest IP,port: B,80 source IP,port: C,9157 dest IP,port: B,80 three segments, all destined to IP address: B, dest port: 80 are demultiplexed to different sockets server: IP address B
Connection-oriented demux:example threaded server application application application P4 (P3 P2) (P3 transport etwork transport network link hysical link physical server:IP physical address B host:IP source IPport:B,80 host:IP addressA dest IPport:A,9157 source IP,port:C,5775 address C dest IP,port:B,80 source IPport:A,9157 dest IP,port:B,80 source IP,port:C,9157 dest IP,port:B,80 Transport Layer3-14
Transport Layer3-14 Connection-oriented demux: example transport application physical link network P3 transport application physical link transport application physical link network P2 source IP,port: A,9157 dest IP, port: B,80 source IP,port: B,80 dest IP,port: A,9157 host: IP address A host: IP address C server: IP address B network P3 source IP,port: C,5775 dest IP,port: B,80 source IP,port: C,9157 dest IP,port: B,80 P4 threaded server
Chapter 3 outline 3.I transport-layer services 3.5 connection-oriented 3.2 multiplexing and transport:TCP demultiplexing ·segment structure 3.3 connectionless transport: reliable data transfer UDP 。flow control 3.4 principles of reliable data connection management transfer 3.6 principles of congestion control 3.7 TCP congestion control Transport Layer3-15
Transport Layer3-15 Chapter 3 outline 3.1 transport-layer services 3.2 multiplexing and demultiplexing 3.3 connectionless transport: UDP 3.4 principles of reliable data transfer 3.5 connection-oriented transport: TCP • segment structure • reliable data transfer • flow control • connection management 3.6 principles of congestion control 3.7 TCP congestion control