The Presentation layer // Tao ra mot cau truc va dinh dang chung cua thong tin
- Coding and conversion // Ma hoa
- Compression //Nen du lieu
- Encryption //Ma hoa (bao mat)
The Session Layer
- Create and maintain dialogs between source and destination applications. // Khoi tao va duy tri cac phien ket noi giua ung dung nguon va dich
- Handles the exchange of information to initiate dialogs, keep them active, and to restart sessions that are disrupted or idle for a long period of time.
Application Layer Protocols and Services
- Domain Name System (DNS) – TCP/UDP Port 53
- Hypertext Transfer Protocol (HTTP) – TCP Port 80
- Simple Mail Transfer Protocol (SMTP) – TCP Port 25
- Post Office Protocol (POP) – UDP Port 110
- Telnet – TCP Port 23
- Dynamic Host Configuration Protocol – UDP Port 67
- File Transfer Protocol (FTP) – TCP Ports 20 and 21
The Client-Server Model
- Client: device requesting // yeu cau
- Server: device responding // dap ung
Peer-to-Peer
- Peer-to-Peer Networking: two or more computers are connected via a network and can share resources (such as printers and files) without having a
dedicated server. - Peer-to-Peer Applications: allows a device to act as both a client and a server within the same communication. In this model, every client is a server and every server a client. Both can initiate
a communication and are considered equal in the communication process.
