总结

计算机之间通信需要知道彼此的地址IP地址。

数据在网络上传输时会被分成小包，称为数据包。

数据包里有元数据，比如发送和接收的IP地址，就像信封上的寄件人和收件人信息。

如何确定数据包顺序？引入TCP，TCP header包含序列号等信息，保证数据包顺序正确。

Communication Between Computers

• Communication between a client computer and a server is similar to sending mail.
• Each computer must have a unique address, known as an IP address, to send and receive data.

IP Addresses

• Definition: An IP address uniquely identifies a machine on the network.
• Format: Written in four sets of digits separated by dots (e.g., 192.168.0.1).
• 32-bit Address: IPv4 addresses are 32-bit, allowing for about 4 billion unique addresses.
• Limitation: The limitation of IPv4 is addressed by IPv6, which uses 128-bit addresses.

Data Transmission

• Internet Protocol (IP): Rules for sending data between computers.
• Packet of Data:
  • Components:
    • Metadata (Header): Source and destination IP addresses.
    • Data Payload: Actual content being sent.
  • Analogy: Envelope containing a letter; the envelope has sender and receiver addresses (metadata), and the letter is the data payload.

Transmission Control Protocol (TCP)

• Function: Ensures data packets are reassembled in the correct order.