Computer Networks · free preview
IPv6
The exhaustion of the 32-bit address space forced a new version of IP, and the designers took the once-in-a-generation chance to simplify as well as enlarge, IPv6 addresses are 128 bits written in colon-separated hexadecimal with double-colon compression, the fixed 40-byte header discards the header checksum and the in-line fragmentation and options machinery, renaming time-to-live honestly as hop limit and folding options into ordered extension headers chained by the next-header field, autoconfiguration and anycast arrive built in, and the transition proceeds by dual stacks and tunnels, slowed by network address translation, the stopgap that already gave the old address space a second life.
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?
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