由TCP的MSS想到的问题
TCP的MSS默认值为536,以保证536+20(IP Head)+20(TCP头)<576,TCP/IP Illustrated中P36第8行提到: Furthmore, a host is not required to receive a datagram larger than 576 bytes.
而在P160页第一行提到: We mentioned in Section 3.2 that a host is required to receive at LEAST a 576-byte IP datagram.
根据TCP/IP Illustrated中的描述,知道576应该是IP的下限,所有主机都支撑这个大小,因此,MSS设置为536后该TCP Segement在网络上传输时候肯定不用分段。这都可以理解,但不理解的是,IP为什么把576作为下限?而不是2的X次方作为下限?