Internet transport-layer protocols D reliable in-order lication delivery (tCp) data link networ o congestion contro data link o flow control o connection seti network g unreliable, unordered data link physical delivery: UDP O no-frills extension of best-effort"IP application g services not available: data link o delay guarantees o bandwidth guarantees Transport Layer 3-6
Transport Layer 3-6 Internet transport-layer protocols reliable, in-order delivery (TCP) congestion control flow control connection setup unreliable, unordered delivery: UDP no-frills extension of “best-effort” IP services not available: delay guarantees bandwidth guarantees application transport network data link physical application transport network data link physical network data link physical network data link physical network data link physical network data link network physical data link physical
Chapter 3 outline 口31 Transport-ayer d3.5 Connection-oriented services transport: TCP 口3.2 Multiplexing and o segment structure demultiplexing o reliable data transfer 03. 3 Connectionless 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 3-7
Transport Layer 3-7 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
Multiplexing/demultiplexing Demultiplexing at rcy host: Multiplexing at send host: delivering received segments gathering data from multiple sockets, enveloping data with to correct socket header later used for demultiplexing) = socket process application P3 P1 application (P2 P4) application fransport fransport fransport network network network link link physical physical SIca host 1 host 2 host 3 Transport Layer 3-8
Transport Layer 3-8 Multiplexing/demultiplexing application transport network link physical P1 application transport network link physical application transport network link physical P3 P2 P4 P1 host 1 host 2 host 3 = socket = process delivering received segments to correct socket Demultiplexing at rcv host: gathering data from multiple sockets, enveloping data with header (later used for demultiplexing) Multiplexing at send host:
How demultiplexing works o host receives IP datagrams o each datagram has source 32 bits IP address destination ip address source port dest port o each datagram carries 1 transport-layer segment other header fields o each segment has source destination port number (recall: well-known port application numbers for specific data applications. ( message) o host uses IP addresses& port numbers to direct segment to appropriate socket TCP/UDP segment format Transport Layer 3-9
Transport Layer 3-9 How demultiplexing works host receives IP datagrams each datagram has source IP address, destination IP address each datagram carries 1 transport-layer segment each segment has source, destination port number (recall: well-known port numbers for specific applications) host uses IP addresses & port numbers to direct segment to appropriate socket source port # dest port # 32 bits application data (message) other header fields TCP/UDP segment format
Connectionless demultiplexing o Create sockets with port g When host receives UDP numbers: segment DatagramSocket mySocketl =new o checks destination port DatagramSocket(99111)i number in segment DatagramSocket my Socket=new o directs UDP segment to DatagramSocket(99222)i socket with that port O UDP socket identified by number two-tuple 口 iP datagrams with (dest IP address, dest port number) different source IP addresses and/or source port numbers directed to same socket Transport layer 3-10
Transport Layer 3-10 Connectionless demultiplexing Create sockets with port numbers: DatagramSocket mySocket1 = new DatagramSocket(99111); DatagramSocket mySocket2 = new DatagramSocket(99222); UDP socket identified by two-tuple: (dest IP address, dest port number) When host receives UDP segment: checks destination port number in segment directs UDP segment to socket with that port number IP datagrams with different source IP addresses and/or source port numbers directed to same socket