Protocol Layer

Network Architecture

1. Provide the connections among many computers
2. Provide efficiency and fairness

Protocol Layer Interfaces

1. Service Interface - Interface between upper layer  and lower layer
2. Peer-to-Peer Interface - Define syntax and semantic of Message between peers

OSI 7-Layer Model and TCP/IP 5-Layer Model

OSI 7-Layer Model and TCP/IP 5-Layer Model

TCP/IP 5-Layer Model

1. Physical Layer - Deals with the transfer of bits over a communication channel
• Functions
• System parameters
• voltage level - decides bit(0,1)
• signal duration
• Bits synchronization
• Data transmission rate
• Physucal attached types
• bus
• ring
• star
• etc...
• Transfer mode
• simplex-channel
• half-duplex transmission
• full-duplex transmission
2. Data Link Layer - Transfer of frame across a transmission link that directly connects two nodes (station to station communication)
• Functions
• Allocate Physical address
• Reliable Data Transmission
• Framing
• Error control
• Flow control
• Medium(Multiple) Access Control(MAC)
• ex) Ethernet
3. Network Layer - Node-to-Node Communication(host-to-host communication)
• Functions
• Routing - Finding the most optimal route
• Switching(=Forwarding) - Deciding path at inner the Router
4. Transport Layer - Process-to-Process Communication
• Functions
• Multiplexing & Demultiplexing
• Segment & Reassembly(SAR)
• Support Connection-Oriented Service
• Error Control
• Flow Control
• Congestion Control - Causes by Router inner the Networks
5. Application Layer - Provide services that are frequently required by applications

참고 : 컴퓨터 네트워크  by 김성철교수