Chapter 3 Transport Layer Chapter goals: Chapter Overview: o understand principles o transport layer services behind transport layer o multiplexing/demultiplexing services: o connectionless transport: UDP o multiplexing/demultiplex Ing o principles of reliable data transfer o reliable data transfer o flow control o connection-oriented transport o congestion control TCP g instantiation and o reliable transfer implementation in the f| ow contro Internet o connection management o principles of congestion contro o TCP congestion control 3: Transport Layer 3a-1
3: Transport Layer 3a-1 Chapter 3: Transport Layer Chapter goals: understand principles behind transport layer services: multiplexing/demultiplex ing reliable data transfer flow control congestion control instantiation and implementation in the Internet Chapter Overview: transport layer services multiplexing/demultiplexing connectionless transport: UDP principles of reliable data transfer connection-oriented transport: TCP reliable transfer flow control connection management principles of congestion control TCP congestion control
Transport services and protocols o provide logical communication lication between app processes running on different hosts data link networ data link o transport protocols run in end systems a transport vs network layer be, physical i network data link services. physical o network layer: data transfer 受 between end systems g transport layer: data application transfer between processes networ data link o relies on, enhances network ayer services 3: Transport Layer 3a-2
3: Transport Layer 3a-2 Transport services and protocols provide logical communication between app’ processes running on different hosts transport protocols run in end systems transport vs network layer services: network layer: data transfer between end systems transport layer: data transfer between processes relies on, enhances, network layer services 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
Transport-layer protocols Internet transport services: lication g reliable. in-order unicast data link networ delive ry (TCp) data link o congestion o flow contro o connection setup be, physical i network data link a unreliable (best-effort physical unordered unicast or 受 multicast delivery: UDP o services not available application o real-time networ data link o bandwidth guarantees o reliable multicast 3: Transport Layer 3a-3
3: Transport Layer 3a-3 Transport-layer protocols Internet transport services: reliable, in-order unicast delivery (TCP) congestion flow control connection setup unreliable (“best-effort”), unordered unicast or multicast delivery: UDP services not available: real-time bandwidth guarantees reliable multicast 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
Multiplexing/demultiplexing Recall: segment-unit of data Demultiplexing: deliverin exchanged between received segments to transport layer entities correct app layer processes o aka TPDU: transport protocol data unit receiver P3 application-layer P4 M(M data applicatio segment trarsport P2 eader M M net work applcation application segment→匠 M transport transport Hnl Metwork network 3: Transport Le 3a-4
3: Transport Layer 3a-4 application transport network M P2 application transport network Multiplexing/demultiplexing Recall: segment - unit of data exchanged between transport layer entities aka TPDU: transport protocol data unit receiver Ht Hn Demultiplexing: delivering received segments to correct app layer processes segment segment M application transport network P1 M M M P3 P4 segment header application-layer data
Multiplexing/demultiplexing Multiplexing gathering data from multiple 32 bits app processes, enveloping data with header later used source port dest port for demultiplexing other header fields multiplexing/demultiplexing g based on sender receiver port numbers, IP addresses application o source, dest port #s in data each segment ( message) o recall: well-known port numbers for specific applications TCP/UDP segment format 3: Transport Layer 3a-5
3: Transport Layer 3a-5 Multiplexing/demultiplexing multiplexing/demultiplexing: based on sender, receiver port numbers, IP addresses source, dest port #s in each segment recall: well-known port numbers for specific applications gathering data from multiple app processes, enveloping data with header (later used for demultiplexing) source port # dest port # 32 bits application data (message) other header fields TCP/UDP segment format Multiplexing: