---
title: 第七堂
tags: 網路概論筆記
---

### Peer - 2 - Peer

### Client - server
- server
- always-on host ( 不會關機000 )
- permantent IP address ( 永久固定 )
- data centers for scaling ( 擴充容易 )
- clients
- communicate with server
- may be intermittently connected
- may have dynamic IP addresses
- do not communicate directly with each other

### Sockets
- API

## TCP services
- Connection-oriented Service
- 連接導向
- 三向交握
- Reliable data transfer service
- 可信賴的傳輸
- Congestion-control service
- 網路雍塞控制
---
## UDP services
- Connectionless Service
- 直接傳封包
- unreliable data transfer service
- 不保證每個封包能抵達目標
- Does not include a congestion-control mechanism
- 無網路雍塞控制
---