信息通信网络概论课件：Chapter_2__Application_and_Layered_Architectures

1、chapter 2 Application and Layered Architectures,2.1 The OSI Reference Model 2.1.1 The seven-layer OSI Reference Model 2.1.2 Unified View of Layers, Protocols, and Services 2.2 Overview of TCP/IP Architecture 2.2.1 TCP/IP Architecture 2.2.2 TCP/IP Protocol: how the layers Work Together 2.2.3 Protocol

2、 Overview 2.3 ATM Architecture 2.4 MPLS Architecture 2.5 WCDMA Protocol Structure,Tasks for communication: Process process ( machines) Routing and forwarding (multiple hops) Frame exchange (physical interface) Network architecture: a set of protocols that specify how every layer is to function Flexi

3、bility to any services layers A set of protocols,preface,Layer: Service: provided by each layer to the layer above through the interface Interface: between layers, service is requested and result is conveyed Each layer invokes a service from layer below without regard to how the service is implement

4、ed, flexibility,preface,Why Layering?,Layering simplifies design, implementation, and testing by partitioning overall communications process into parts Protocol in each layer can be designed separately from those in other layers Protocol makes “calls” for services from layer below Layering provides

5、flexibility for modifying and evolving protocols and services without having to change layers below Monolithic non-layered architectures are costly, inflexible, and soon obsolete,2.1 THE OSI REFERENCE MODEL,ISO: International Organization of Standardization OSI: Open System Interconnection Protocol

6、stack: a list of protocols used by a certain system, one protocol per layer, is called a protocol stack Protocol: an agreement between the communicating parties on how communication proceed,2.1.1 The Seven-Layer OSI Reference Model,Application Layer,Presentation Layer,Session Layer,Transport Layer,N

7、etwork Layer,Data Link Layer,Physical Layer,Application Layer,Presentation Layer,Session Layer,Transport Layer,Network Layer,Data Link Layer,Physical Layer,Network Layer,Application,Application,Data Link Layer,Physical Layer,Network Layer,Data Link Layer,Physical Layer,Communicating End Systems,One

8、or More Network Nodes,End-to-End Protocols,Physical Layer,Transfers bits across link (channel) Definition Retransmission of frames link connection: Activation, maintenance, n+1: DNS, n: UDP ). Confirmed or unconfirmed IDU: Interface Data Unit ：data passed through SAP between adjacent layers; ICI: In

9、terface Control Information： control information in IDU PCI : Protocol Control Information , exchanged between peer layer n entities,Some Terminologies：,Layers, Services connectionless service can be confirmed or unconfirmed.,n-PDU,Segmentation corresponds to the part of the OSI network layer a sing

10、le service: best-effort connectionless packet transfer TCP/IP network interface layer: the network-specific aspects of the transfer of packets; a clear separation of the internet layer from the technology-dependent network interface layer,2.2.1 TCP/IP Architecture,(ICMP, ARP),Diverse network technol

11、ogies,Reliable stream service,User datagram service,Distributed applications,HTTP,SMTP,RTP,TCP,UDP,DNS,Best-effort connectionless packet transfer,Internet Protocol Approach,IP packets transfer information across Internet Host A IP router router router Host B IP IP layer in each router determines nex

12、t hop (router) Network interfaces transfer IP packets across networks,Host B,Internet layer and network interface layer,Internet Names second 24 bits are serial number 00:90:27:96:68:07 12 hex numbers,2.2.2 TCP/IP Protocol: How the Layers Work Together,We show: Examples of each of the layers How the

13、 layers interact across the interface between them How the PDUs of a layer are built and what key info is in the header The relationship between physical address and IP address How an IP packet or datagram is routed across several networks,2.2.2 TCP/IP Protocol: How the Layers Work Together,For exam

14、ple: Figure: a server, a workstation, a router, Ethernet LAN, a remote PC with a p2p link NOTE: from the view of IP, the Ethernet LAN and the p2p link constitute two different networks,A example of an internet _Ethernet and p2p link,Example internet,(1,1),s,(1,2),w,(2,1),(1,3) r,(2,2),PPP Net id=2,E

15、thernet (net id=1),PC,Server,Router,Workstation,*PPP does not use addresses,IP ADDRESSES and PHYSICAL ADDRESSES,In the Internet each host is identified by a globally unique IP address, which identifies the hosts network interface. Router: two IP addresses, two network interfaces IP address: a networ

16、k ID and a host ID, (1, 1), (1, 3) In a LAN: Physical address: Ethernet, NIC, 48-bit address. r, s, w,Encapsulation,IP header: source and destination IP address, other info Ethernet header: source and destination physical addresses network protocol type (e.g. IP),IP packet from workstation to server

17、,IP packet has (1,2) IP address for source and (1,1) IP address for destination IP table at workstation indicates (1,1) connected to same network, so IP packet is encapsulated in Ethernet frame with addresses w and s Ethernet frame is broadcast by workstation NIC and captured by server NIC NIC exami

18、nes protocol type field and then delivers packet to its IP layer,(1,1),s,(1,2),w,(2,1),(1,3) r,(2,2),PPP,Ethernet,PC,Server,Router,Workstation,IP packet from server to PC,(1,1),s,(1,2),w,(2,1),(1,3) r,(2,2),PC,Server,Router,Workstation,IP packet has (1,1) and (2,2) as IP source and destination addre

19、sses IP table at server indicates packet should be sent to router, so IP packet is encapsulated in Ethernet frame with addresses s and r Ethernet frame is broadcast by server NIC and captured by router NIC NIC examines protocol type field and then delivers packet to its IP layer IP layer examines IP

20、 packet destination address and determines IP packet should be routed to (2,2) Routers table indicates (2,2) is directly connected via PPP link IP packet is encapsulated in PPP frame and delivered to PC PPP at PC examines protocol type field and delivers packet to PC IP layer,How the layers work tog

21、ether,Network interface,IP,TCP,HTTP,Network interface,IP,Network interface,IP,TCP,HTTP,Router,(1,1),s,(2,1),(1,3) r,(2,2),PPP,Ethernet,(a),(b),Server,PC,PC,Server,Router,TCP uses node-to-node Unreliable packet transfer of IP Server IP address transport protocol type,Ethernet Header contains source n

22、etwork protocol type,PROCESS-to-PROCESS,Socket address: the port number, the IP address, and the protocol type. A process-to-process: uniquely specified by the source and dest socket addresses For example: the sources socket: (TCP, (2,2), C) The dests socket: (TCP, (1,1), 80) The combination: (TCP,

23、(2,2), C, (1,1), 80),TCP provides a service to the application layer which is: connection-oriented: connection established before communication takes place, terminated when done. reliable: no-loss, no-duplicates, no-data-corruption, and Ordered bidirectional,Service provided by TCP,UDP provides a se

24、rvice to the application layer which is: connectionless: no connection established before communication takes place, directly delivery unreliable: loss, duplicates, data-corruption, and Unordered,Service provided by UDP,2.3 ATM Architecture,ATMAsynchronous transfer mode User Plane: transfer of user

25、information; flow control; error recovery Control Plane: setting up, management, and release of connections Layer Management Plane: management of layer entities a connection-oriented packet-switching technique; combines features of packet switching and TDM circuit switching; has QoS attributes, suitable for an integrated services network, converting all traffic that flows in the network into 53-byte bloc