TCP/IP

1. IP/IP Packet

IP (Internet Protocol)

Transmits data in communication units called packets to specified IP addresses

IP Limitations

• Connectionless: Even if there's no recipient for packets or service is unavailable, client still sends packets as-is

• Unreliable: If there's a failure in servers during data transmission and packets are lost, client cannot detect it, and packets may not arrive in order

2. TCP

TCP Segment

Includes source PORT, destination PORT, transmission control, sequence, verification information, etc. that can supplement source IP and destination IP information of IP packets

TCP (Transmission Control Protocol) Characteristics

• Connection-oriented: TCP 3-way handshake (virtual connection)

• Data transmission guarantee: Because it returns responses

• Order guarantee: If packets don't arrive in order, can request packet retransmission based on information in TCP segment

• Reliable protocol

3. UDP

UDP (User Datagram Protocol) Characteristics

• Simple protocol with only PORT and checksum (duplicate check) field information added to IP

• Has almost no functionality but can be customized

• Connectionless: No TCP 3-way handshake

• No data transmission guarantee

• No order guarantee

• Data transmission and order are not guaranteed but simple and fast

• Frequently used for services where continuity is more important than reliability (ex. real-time streaming)