RFC 8200 / START HERE
IPv6, before the details
IPv6: Internet Protocol version 6
IPv6 addresses devices and carries packets across interconnected networks. Its much larger address space is a major difference from IPv4.
The idea in one picture
A device addresses a packet
Routers carry it across networks
The destination receives it
A simplified picture of the idea; the chapters explain the actual mechanisms.
Why it exists
The Internet needs room for many devices and networks. IPv6 provides 128-bit addresses and its own packet format; it is a different IP version.
A familiar example
A phone reaches an IPv6-enabled service using an address written as groups of hexadecimal digits.
Helpful background
You can start here without reading another RFC. If these ideas are unfamiliar, these short introductions may help.
What you’ll learn next
Begin with chapter one, or choose a topic.
- Addresses identify interfacesIPv6 expands addresses to 128 bits and supports unicast, multicast, and anycast delivery.→
- Read the fixed IPv6 headerThe common IPv6 header is 40 octets. Its fields describe the packet and identify the next header.→
- Follow the next header chainExtension headers form an ordered chain between the fixed header and the upper-layer payload.→
- Fit packets to the pathEvery IPv6 link supports at least a 1280-octet packet, directly or through lower-layer fragmentation.→
- Reassemble source fragmentsA source can split a packet with Fragment headers. Reassembly belongs at the destination.→
- Forward with explicit limitsHop Limit changes at each forwarding node. Flow Label and Traffic Class express different treatment information.→
This introduction explains RFC 8200 (2017). Read the original RFC ↗