throughput and window size

The wisdom of STUP protocol is all about the window size. The throughput of a TCP communication is limited by two windows: the congestion window and the receive window. The congestion window can determine how many bytes that can be send a simple piece of time …

STUP Packet Structure

Brief Introduction of TCP & UDP Packet Structure

STUP pretend itself as a protocol at the Transmission Layer, but actually it's absolutely an Application Layer protocol. So before we start, I'd like to recall some knowledge of two important Transmission Layer protocol: TCP & UDP.

It is well known …

What is STUP?

STUP is the abbreviation of "Speeded/Secure Tcp-like Udp Protocol", which means that it's another TCP over UDP protocol.

Why TCP over UDP?

TCP is a network protocol for general purpose, and it's one of the most commonly used internet protocol on this planet. It is reliable …

在数据通信协议中，可选的信息或字段通常使用type-length-value（a.k.a TLV）元素来进行编码。

• Type - 类型

用来标示字段类型的值，通常是一个二进制值或简单的字母

• Length - 长度

字段长度，单位通常为Byte

• Value - 值

一个变长的比特数组用来存储这个字段的值

优势

• TLV序列方便遍历查找
• 新的字段可以无痛的加入现有的协议中。解析的时候，对于未知的字段，可以轻松的跳过。这点与XML类似
• TLV元素的顺序可以是随意的
• TLV元素通常使用二进制存储，可以使解析速度加快并且使数据更小
• TLV可以与XML数据相互转换，易于人类阅读

例子

在这里，我们以protobuf的可选和变长字段为例。

field_number ++ wire_type

每一个protobuf的字段在传输时，都会加上field_number和wire_type这两个值，这两个值组成这个字段的key。

key = (field_number << 3) | wire_type

field_number标明了字段的编号，方便协议向前向后的兼容。而 …