Example E. g a can only speak Chinese, B can only speak spanish how can a communicate with B? a finds a translator c, who can speak chinese and English -B finds a translator d, who can speak spanish and English Two layers -Higher layer A and b -Lower layer: C and d
11 Example • E.g., A can only speak Chinese, B can only speak Spanish, how can A communicate with B? —A finds a translator C, who can speak Chinese and English —B finds a translator D, who can speak Spanish and English • Two layers: —Higher layer: A and B —Lower layer: C and D
A TwO-layer example How to communicate? NigeriA ■■■■■■■■■■■■■■■ aver messages messages in chimese in Spanish Lower aver Messages in English C D Lower layer provides services to the next higher layer 12
12 A Two-layer example messages in Chinese messages in English messages in Spanish How to communicate? A C B D Higher Layer Lower Layer Lower layer provides services to the next higher layer
Section 2 TCP/IP Protocol Architecture 13
13 Section 2 TCP/IP Protocol Architecture
Protocol Architecture asks of communications are broken up into modules Each module( or layer can have its own protocol In very general terms, communications can be said to involve three components: applications, computers, and networks For example, file transfer could use three modules(or layers -File transfer application Communications service module Network access module The stack of protocols is called"Protocol Stack Or protocol architecture 14
14 Protocol Architecture • Tasks of communications are broken up into modules — Each module (or layer) can have its own protocol • In very general terms, communications can be said to involve three components: applications, computers, and networks. • For example, file transfer could use three modules (or layers) — File transfer application — Communications service module — Network access module • The stack of protocols is called “Protocol Stack” — Or Protocol Architecture
TCP/P Protocol Architecture Developed by the US Defense Advanced Research Project Agency (DARPA)for its packet switched network(ARPANe Used by the global Internet It consists of a large collection of protocols that have been issued as Internet standard by the Internet architecture Board (IaB) Checkhttp://www.ietf.org/rfc/rfc2026.txt The TCP /IP protocol architecture organizes the communication task into five relatively independent layers Layer 5: Appliation laer Layer 4: Transport layer or Host to host (tcp belongs to this layer) Layer 3: Internet layer, or Network layer(ip belongs to this layer) Layer 2: Network access layer, or Link layer Layer 1: Physical layer Remark: Each layer can have lots of different protocols 15
15 TCP/IP Protocol Architecture • Developed by the US Defense Advanced Research Project Agency (DARPA) for its packet switched network (ARPANET) • Used by the global Internet • It consists of a large collection of protocols that have been issued as Internet standard by the Internet Architecture Board (IAB). — Check http://www.ietf.org/rfc/rfc2026.txt • The TCP/IP protocol architecture organizes the communication task into five relatively independent layers: — Layer 5: Application layer — Layer 4: Transport layer, or Host to host (TCP belongs to this layer) — Layer 3: Internet layer, or Network layer (IP belongs to this layer) — Layer 2: Network access layer, or Link layer — Layer 1: Physical layer • Remark: Each layer can have lots of different protocols!