TCP刚刚建立连接时，拥塞窗口cwnd和慢启动门限ssthresh的初始值是多少？

Question

1、TCP刚刚建立连接时，拥塞窗口cwnd和慢启动门限ssthresh的初始值是多少？
2、当发生拥塞时，如何计算新的ssthresh值。

Answer 1

这最好是去查RFC文档啊，给你引用部分，其他你自己可以去里面搜：

IW, the initial value of cwnd, MUST be set using the following
   guidelines as an upper bound.

   If SMSS > 2190 bytes:
       IW = 2 * SMSS bytes and MUST NOT be more than 2 segments
   If (SMSS > 1095 bytes) and (SMSS <= 2190 bytes):
       IW = 3 * SMSS bytes and MUST NOT be more than 3 segments
   if SMSS <= 1095 bytes:
       IW = 4 * SMSS bytes and MUST NOT be more than 4 segments

Answer 2

以smss字节1045-2190为两个分界，cwnd为2-4个SMSS。ssthresh应该根据自己需求设置