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IPv6
32位地址空间的耗尽迫使IP推出新版本，设计者抓住这千载难逢的机会，在扩展地址的同时也进行了简化：IPv6地址为128位，采用冒号分隔的十六进制书写并支持双冒号压缩；固定的40字节首部去除了首部校验和以及行内分片和选项机制，将生存时间诚实地重命为跳数限制，并把选项折叠进由下一个首部字段链接的有序扩展首部中；自动配置和任播成为内置功能；过渡则通过双栈和隧道进行，但被网络地址转换所拖慢——正是这一权宜之计曾给旧地址空间带来第二次生命。
1. Why a New Version
Why a New Version
2. Addresses Written Large
Addresses Written Large
3. The Simpler Header
The Simpler Header
4. Living Together
Living Together
5. The real motivation
What finally forced the design of a new IP version, after decades of salvage by subnetting and classless routing?
6. Reading the notation
How is an IPv6 address conventionally written, and what does a double colon mean in one?
7. The deleted checksum
Why does the IPv6 header carry no header checksum?
8. Extension headers
How does IPv6 carry options without forcing every router to parse them?
9. Fragmentation relocated
Who fragments an oversized packet in IPv6, and what does a router do instead?
10. The slow transition
What has most effectively delayed the world's move to IPv6?
11. The address length
The designers of the new IP version enlarged the address field of every datagram. How many bits long is an IPv6 address?
12. The fixed header size
The IPv6 base header is always how many bytes long?
13. The honest name
IPv6 renames the old time-to-live field to reflect its actual per-hop use. What is the new name?
14. The successor to broadcast
IPv6 has no broadcast address. Which class of addresses, identified by its own prefix, performs broadcast's former jobs?