ĐIỆN tử VIỄN THÔNG communication network (1) khotailieu

What is a communication network? Communication network:  The equipment (hardware & software) and facilities that provide the basic communication service  Virtually invisible to the user; Usually represented by a cloud   Equipment: Routers, servers, switches, multiplexers, hubs, modems, … Facilities:   Copper wires, coaxial cables, optical fiber Ducts, conduits, telephone poles … Communication network What is a communication network? (cont) Focus on network that use electronic or optical technologies Example:  Telephone networks  Computer networks  Television broadcast networks  Cellular telephone network  and Internet… Communication network What is a communication network? (cont) A simple model of a telecommunication network consists of  Node:   terminals network nodes  Links between nodes  Access network:   connects the terminals to the network nodes Trunk network  connects the network nodes to each other link Network node terminal Communication network What is a communication network? (cont) Shared medium as an access network  In the previous model:    connections between terminals and network nodes are point-to-point type => no resource sharing within the access netw.) In some cases, such as:   mobile telephone network local area network (LAN) the access network consists of shared medium:  users have to compete for the resources of this shared medium  multiple access (MA) techniques are needed Communication network What is a communication network? (cont) What is communication network used for?  Provides a service:  Transfer of information between users located at various geographical point Communication network Communication Services & Applications Services & Applications  Service: Basic information transfer capability     Applications build on communication services    Internet transfer of individual block of information Internet reliable transfer of a stream of bytes Real-time transfer of a voice signal E-mail & web build on reliable stream service Fax and modems build on basic telephone service New applications build on multiple networks  SMS builds on Internet reliable stream service and cellular telephone text messaging Data Communication Communication Services & Applications   A communication service enables the exchange of information between users at different locations Communication services & applications are everywhere Data Communication Communication Services & Applications   A communication service enables the exchange of information between users at different locations Communication services & applications are everywhere Data Communication Communication Services & Applications   A communication service enables the exchange of information between users at different locations Communication services & applications are everywhere Data Communication Communication Services & Applications   A communication service enables the exchange of information between users at different locations Communication services & applications are everywhere Data Communication Communication Services & Applications   A communication service enables the exchange of information between users at different locations Communication services & applications are everywhere Data Communication Communication Services & Applications   A communication service enables the exchange of information between users at different locations Communication services & applications are everywhere Data Communication Switching modes Switching mode Circuit switching - telephone networks - mobile telephone networks - optical networks Packet switching - data networks - two possibilities • connection oriented: X.25, FR • connectionless: Internet (IP), SS7 Data Communication CCS (Common Channel Signaling)  CCS tiêu biểu CCS#7, phát triển vào năm 1970 để điều khiển việc thiết lập gọi Báo hiệu kênh chung   Các xử lý điều khiển điều khiển chuyển mạch giao tiếp với chuyển mạch khác để trao đổi tin báo hiệu Các tin báo hiệu trao đổi qua đường trung kế số riêng biệt nhờ modem Data Communication CCS (Common Channel Signaling)     Mạng báo hiệu CCS  mạng thực việc kết nối máy tính điều khiển chuyển mạch để trao đổi tin báo hiệu SSP: Service Switching Point (signal to message) STP: Signal Transfer Point (packet Switch) SCP:Service Control Point (processing) CCS (Common Channel Signaling)  Mạng báo hiệu CCS  Chồng giao thức phát triển để hỗ trợ báo hiệu  Mạng báo hiệu dựa mạng chuyển mạch gói có độ tin cậy cao  Mạng báo hiệu CCS cho phép cung cấp nhiều dịch vụ mới: nhận dạng người gọi (caller id); chuyển tiếp gọi; gọi chờ; người sử dụng di động… nhờ có xử lý sở liệu thêm vào mạng báo hiệu Data Communication CCS (Common Channel Signaling)  Chồng giao thức hệ thống báo hiệu           MTP: Message Transfer Part SSCP: signaling connection control part TUP: Telephone user part ISUP: ISDN user part TCAP = Transaction capabilities part lớp thấp đảm bảo việc phân phát tin đến nút báo hiệu SCCP cho phép tin gửi đến ứng dụng TCAP xác định tin giao thức ứng dụng ISUP thực voeẹc thiết lập giải phóng gọi TUP thay cho ISUP số nước Traffic and Overload Control in Telephone Networks Traffic Management & Overload Control  Telephone calls come and go People activity follow patterns  Mid-morning & mid-afternoon at office  Evening at home  Summer vacation ● Outlier Days are extra busy  Mother’s Day, Christmas, … ● Disasters & other events cause surges in traffic ⇒ Need traffic management & overload control  Traffic and Overload Control in Telephone Networks Traffic concentration ... Access network:   connects the terminals to the network nodes Trunk network  connects the network nodes to each other link Network node terminal Communication network What is a communication network? ... Cellular telephone network  and Internet… Communication network What is a communication network? (cont) A simple model of a telecommunication network consists of  Node:   terminals network nodes...What is a communication network? (cont) Focus on network that use electronic or optical technologies Example:  Telephone networks  Computer networks  Television broadcast networks  Cellular