元数据
元数据
[!abstract] TCP:IP详解_卷1_协议_英文_第2版
TCP:IP详解_卷1_协议_英文_第2版|200 - 书名： TCP:IP详解_卷1_协议_英文_第2版
- 作者： Kevin R. Fall; W. Richard Stevens
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- PC地址：https://weread.qq.com/web/reader/25d42473643425f386344314474314635356244367a76373148347475344c62a71
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5.2 IPv4 and IPv6 Headers
📌 widespread
⏱ 2025-11-21 11:20:53 ^CB-8cD1Dt1F55bD6zv71H4tu4Lb-93-3212-3222
📌 Explicit
⏱ 2025-11-21 11:21:20 ^CB-8cD1Dt1F55bD6zv71H4tu4Lb-93-3469-3477
📌 Congestion
⏱ 2025-11-21 11:21:25 ^CB-8cD1Dt1F55bD6zv71H4tu4Lb-93-3478-3489
📌 indicator
⏱ 2025-11-21 11:21:34 ^CB-8cD1Dt1F55bD6zv71H4tu4Lb-93-3517-3526
📌 forwarded
⏱ 2025-11-21 11:21:47 ^CB-8cD1Dt1F55bD6zv71H4tu4Lb-93-3650-3659
读书笔记
5.2 IPv4 and IPv6 Headers
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📌 5.2 IPv4 and IPv6 Headers
Figure 5-1 shows the format of an IPv4 datagram. The normal size of the IPv4 header is 20 bytes, unless options are present (which is rare). The IPv6 header is twice as large but never has any options. It may have extension headers, which pro-vide similar capabilities, as we shall see later. In our pictures of headers and data-grams, the most significant bit is numbered 0 at the left, and the least significant bit of a 32-bit value is numbered 31 on the right. The 4 bytes in a 32-bit value are transmitted in the following order: bits 0–7 first, then bits 8–15, then 16–23, and bits 24–31 last. This is called big endian byte ordering, which is the byte ordering required for all binary integers in the TCP/IP headers as they traverse a network. It is also called network byte order. Computer CPUs that store binary integers in other formats, such as the little endian format used by most PCs, must convert the header values into network byte order for transmission and back again for reception.
5.2.1 IP Header Fields
The first field (only 4 bits or one nibble wide) is the Version field. It contains the version number of the IP datagram: 4 for IPv4 and 6 for IPv6. ^37992928-84JlS7a03
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