Transmission Methods#
Classified by Transmission Direction#
- Simplex: A working mode that can only transmit in one direction
- Duplex: Only allows data to pass in one direction on the line at the same time
- Full Duplex: Both sides can communicate data simultaneously
Classified by Transmission Object#
- Unicast: One-to-one
- Multicast: One-to-many
- Broadcast: One-to-all
Data Exchange#
Circuit, Message, Packet
Circuit Switching#
The entire message is continuously transmitted from the source to the destination
Message Switching#
The entire message is first sent to the adjacent node
Packet Switching#
Divide a message into multiple packets, send them to the adjacent node, look up the forwarding table, and then forward to the next node
Communication Protocols and Architectures#
Three Elements of Network Protocols#
Mnemonic: Three elements of network protocols, syntax, semantics, and synchronization
🤦The new version is syntax, semantics, and synchronization
- Syntax
- Semantics
- Synchronization
OSI Reference Model#
==Ordered from low to high, lower layers serve upper layers==
Physical Layer, Data Link Layer, Network Layer, Transport Layer, Session Layer, Presentation Layer, Application Layer
- Application Layer: Uses application programs through network services
- Presentation Layer:
- Session Layer
- Transport Layer
- Network Layer: Unit is packet, builds on the data link layer, implements communication between points, provides routing functions, implements congestion control, network interconnection, and other functions
- Data Link Layer: Unit is frame, provides services between nodes based on the physical layer, adopts error control and flow control methods, implements network interconnection
- Physical Layer: Unit is bit, uses transmission media to establish communication between network nodes
TCP/IP Reference Model#
- Network Interface Layer: Physical Layer and Data Link Layer
- Internet Layer: Network Layer
- Transport Layer
- Application Layer: Session Layer, Presentation Layer, Application Layer