1. TCP

TCP, universally because it provides reliable end to end bidirectional byte stream service that almost all applications want

three-way handshake Tear down Propeties TCP:Port Demultiplexing

Ayana Port Numbers

TCP三次握手中SYN，ACK，Seq含义

• PSH tells TCP layer delivers message immediately upon arrival, useful sending short segment data which is time critical such as a key stroke

TCP的三次握手与四次挥手理解及面试题（很全面）

2. UDP

UDP

• checksum has IPv4 message because it helps to check

3. ICMP

IP协议以及ICMP、Ping
ICMP协议详解

Ping

4. End-to-End Principle

End-to-End Principle Error Detection

• D has some bugs in memory, thus when it receives data from C and transmit to E, some of the data will be lost
• So the correct position for error detection should be in the application layer, rather than link layer.

端对端原则的思考及反思

5. Error Detection: 3 chemes

Error Detection: 3 chemes Checksum CRC

6. Finite State Machine

Finite State Machine
Finite State Machine

7. Reliable Communication

7.1 Stop and Wait

Stop and Wait

• How to detect duplicates?

use 1-bit counter

Problem

7.2 Sliding Window

Sliding Window
Sliding Window Sender Sliding Window Receiver

• cumulative acks: If 4 is lost, the receiver will send ack 3 until time out, so the sender will retransmit 4

Sequence Space

7.3 Retransmission Strategies

Retransmission Strategies Go-back-N Quiz

• because receiver window if 1, so it can not buffer any other packets

7.4 TCP Header

TCP Header

• sequence number: first byte of sliding window

TCP数据报首部

7.5 TCP set up and tear down