Connectionless demux(cont) DatagramSocket serverSocket new DatagramSocket(6428)i P3 P3 P1 sP:6428 sP:6428 DP:9157 DP:5775 sP:9157 SP:5775 client DP: 6428 DP:6428 server Client 工P:A 工P:C SP provides return address Transport Layer 3-11
Transport Layer 3-11 Connectionless demux (cont) DatagramSocket serverSocket = new DatagramSocket(6428); Client IP:B P3 client IP: A P1P1 P3 server IP: C SP: 6428 DP: 9157 SP: 9157 DP: 6428 SP: 6428 DP: 5775 SP: 5775 DP: 6428 SP provides “return address
Connection-oriented demux o TCP socket identified o Server host may support by 4-tuple many simultaneous tCp o source ip address sockets o source port number o each socket identified by o dest ip address its own 4-tuple o dest port number g Web servers have O recy host uses all four different sockets for values to direct each connecting client segment to appropriate o non-persistent HT TP will socket have different socket for each request Transport Layer 3-12
Transport Layer 3-12 Connection-oriented demux TCP socket identified by 4-tuple: source IP address source port number dest IP address dest port number recv host 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 cont P3 P3)(P4 P1 sP:80 sP:80 DP:9157 DP:5775 sP:9157 SP:5775 client DP:80 DP:80 server Client IP: A 工P:C Transport Layer 3-13
Transport Layer 3-13 Connection-oriented demux (cont) Client IP:B P3 client IP: A P3 P1P1 server IP: C SP: 80 DP: 9157 SP: 9157 DP: 80 SP: 80 DP: 5775 SP: 5775 DP: 80 P4
Chapter 3 outline 口31 Transport-ayer 03.5 Connection-oriented services transport: TCP 03.2 Multiplexing and o segment structure demultiplexing o reliable data transfer 了3.3 Connection|ess flow control transport: UDP o connection management O 3.4 Principles of 口36 Principles of reliable data transfer congestion control 口3.7 TCP congestion contro Transport layer 3-14
Transport Layer 3-14 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
UDP: User datagram Protocol [RFC 768 o"no frills, ""bare bones" Internet transport Why is there a UDP? protocol o no connection 0" best effort"service, UDP establishment(which can segments may be add delay o lost g simple: no connection state o delivered out of order at sender receiver to app 口sma| segment header g connectionless g no congestion control: UDP o no handshaking between can blast away as fast as UDP sender receiver desired o each UDP segment handled independently of others Transport layer 3-15
Transport Layer 3-15 UDP: User Datagram Protocol [RFC 768] “no frills,” “bare bones” Internet transport protocol “best effort” service, UDP segments may be: lost delivered out of order to app connectionless: no handshaking between UDP sender, receiver each UDP segment handled independently of others Why is there a UDP? no connection establishment (which can add delay) simple: no connection state at sender, receiver small segment header no congestion control: UDP can blast away as fast as desired