Internet校验和为校验和添加十六进制数

Question

我遇到了以下创建Internet校验和的示例：

Take the example IP header 45 00 00 54 41 e0 40 00 40 01 00 00 0a 00 00 04 0a 00 00 05:

1. Adding the fields together yields the two’s complement sum 01 1b 3e.
2. Then, to convert it to one’s complement, the carry-over bits are added to the first 16-bits: 1b 3e + 01 = 1b 3f.
3. Finally, the one’s complement of the sum is taken, resulting to the checksum value e4c0.

我想知道如何将IP头添加到一起以获得01 1b 3e？你知道吗

Answer 1

IP报头与4位十六进制进位数字相加。 i、 e.添加的前3个数字是0x4500+0x0054+0x41e0+。。。你知道吗