Data CommunicationCommunication Services & Applications Services & Applications Service: Basic information transfer capability Internet transfer of individual block of information
Trang 1Communication network
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 …
Trang 2Communication 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…
Trang 3Communication network
What is a communication network? (cont)
A simple model of a telecommunication network consists of
Node:
terminals
network nodes
Links between nodes
terminal
Network node
link
Access network:
connects the terminals to the
network nodes
Trunk network
connects the network nodes to
each other
Trang 4Communication 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
Trang 5Communication 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.
Trang 6Data Communication
Communication Services & Applications
Services & Applications
Service: Basic information transfer capability
Internet transfer of individual block of information
Internet reliable transfer of a stream of bytes
Real-time transfer of a voice signal
Applications build on communication services
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
Trang 7Data Communication
Communication Services & Applications
A communication service enables the exchange of information between users at different locations
Communication services & applications are everywhere
Trang 8Data Communication
Communication Services & Applications
A communication service enables the exchange of information between users at different locations
Communication services & applications are everywhere
Trang 9Data Communication
Communication Services & Applications
A communication service enables the exchange of information between users at different locations
Communication services & applications are everywhere
Trang 10Data Communication
Communication Services & Applications
A communication service enables the exchange of information between users at different locations
Communication services & applications are everywhere
Trang 11Data Communication
Communication Services & Applications
A communication service enables the exchange of information between users at different locations
Communication services & applications are everywhere
Trang 12Data Communication
Communication Services & Applications
A communication service enables the exchange of information between users at different locations
Communication services & applications are everywhere
Trang 13Data Communication
Switching modes
Switching mode
Circuit switching Packet switching
- telephone networks
- mobile telephone networks
- optical networks
- data networks
- two possibilities
• connection oriented: X.25, FR
• connectionless: Internet (IP), SS7
Trang 14Data Communication
CCS (Common Channel Signaling)
CCS tiêu biểu là CCS#7, phát triển vào những năm 1970 để điều khiển việc thiết lập cuộc gọi
Các bộ xử lý điều khiển điều khiển chuyển mạch giao tiếp với chuyển mạch khác
để trao đổi các bản tin báo hiệu.
Các bản tin báo hiệu được trao đổi qua đường trung kế số riêng biệt nhờ các modem
Báo hiệu kênh chung
Trang 15CCS (Common Channel Signaling)
Mạng báo hiệu CCS
là mạng thực hiện việc kết nối các máy tính điều khiển các chuyển mạch để trao đổi các bản tin báo hiệu
SSP: Service Switching Point (signal to message)
STP: Signal Transfer Point (packet Switch)
SCP:Service Control Point (processing)
Trang 16Data Communication
CCS (Common Channel Signaling)
Mạng báo hiệu CCS
Chồng giao thức được phát triển để hỗ trợ báo hiệu
Mạng báo hiệu được dựa trên 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 cuộc gọi; cuộc gọi chờ; người sử dụng di động… nhờ có các bộ xử lý và cơ sở
dữ liệu được thêm vào mạng báo hiệu
Trang 17CCS (Common Channel Signaling)
Chồng giao thức hệ thống báo hiệu
3 lớp thấp đảm bảo việc phân phát các bản tin đến các nút báo hiệu.
SCCP cho phép các bản tin được gửi đến các ứng dụng
TCAP xác định các bản tin và các giao thức giữa các ứng dụng
ISUP thực hiện voeẹc thiết lập và giải phóng các cuộc gọi cơ bản
TUP thay thế cho ISUP ở một số nước
MTP: Message Transfer Part
SSCP: signaling connection control part
TUP: Telephone user part
ISUP: ISDN user part
TCAP = Transaction capabilities part
Trang 18Traffic 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
Trang 19Traffic and Overload Control in Telephone Networks
Traffic concentration