The Intertubes

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Over the history of IPv6, there have been many classful address models; TLA and NLA being outstanding examples. They have all been shown to be mistakes. The last remaining is a magic boundary at /64. This document removes that last bit of useless magic.

Over the history of IPv6, there have been many classful address models; TLA and NLA being outstanding examples. They have all been shown to be mistakes. The last remaining is a magic boundary at /64. This document removes that last bit of useless magic.

It is assumed that the reader understands IPv6, , IP Version 6 Addressing Architecture, see , and the proposed changes to , see .

Some confusion has been caused by the IP Version 6 Addressing Architecture, , and the proposed changes in with respect to allowed maximum prefix lengths and the minimum host part on a link. In the meantime, link prefixes of varied lengths, /127, /126, /124, /120, ... /64 have been successfully deployed for many years. Having the formal specification be unclear risks potential mis-implementation by the naive, which could result in operational disasters.

To state it simply, IPv6 unicast routing is based on prefixes of any valid length up to 128 except for links where an Internet Standard such as Stateless Address Configuration , or Using 127-Bit IPv6 Prefixes on Inter-Router Links is in use.

For historical reasons, when a prefix is needed on a link, barring other considerations, a /64 is traditional. The length of the prefix identifier in Stateless Address Configuration, is a parameter; its length needs to be sufficient for effective randomization for privacy reasons. For example, a /48 would be sufficient. But operationally we recommend, barring strong considerations to the contrary, using 64-bits for SLAAC in order not to discover where 64-bits was hard-coded.

This document has no known security impact.

This document has no IANA Considerations.

The original draft was by Randy Bush, who was immediately aided and abetted by Job Snijders, [ your name here ].

The authors wish to thank .