계층 간 데이터 송수신 과정
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캡슐화 (encapsulation)
- 상위 계층의 헤더와 페이로드를 하위 계층의 페이로드에 포함시키고 하위 계층의 헤더를 삽입하는 과정.
- 네트워크 송신 단말에서 캡슐화를 거친다.
비캡슐화 (decapsulation)
- 하위 계층에서 헤더를 제거하고 상위 계층으로 페이로드를 올려보내는 과정.
- 네트워크 수신 단말에서 비캡슐화를 거친다.
PDU (Protocol Data Unit)
![notion image](https://www.notion.so/image/https%3A%2F%2Fs3.us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F4e4a89ef-cdf2-4789-9db1-318525f0235c%2FOSI_and_TCP_IP_Models.jpeg%3FX-Amz-Algorithm%3DAWS4-HMAC-SHA256%26X-Amz-Content-Sha256%3DUNSIGNED-PAYLOAD%26X-Amz-Credential%3DAKIAT73L2G45EIPT3X45%252F20230218%252Fus-west-2%252Fs3%252Faws4_request%26X-Amz-Date%3D20230218T042710Z%26X-Amz-Expires%3D86400%26X-Amz-Signature%3De45c70851f524cdf826faed251946035ad67b0cfdb6e3a73c768b2bccff6a13e%26X-Amz-SignedHeaders%3Dhost%26x-id%3DGetObject?table=block&id=27baf5f8-5d67-41e2-a978-358875681701&cache=v2)
- 각 계층마다 정해놓은 데이터의 단위
- 헤더와 페이로드로 구성한다.
계층 | PDU |
application | message |
transport | segment(TCP), datagram(UDP) |
internet | packet |
link | frame, bit |