Re: [v6ops] RFC 4291, link local address defination

[Ole Troan <[e-mail]>]

Praveen,

> As per RFC 4291 section 2.5.6 link local address are defines with the prefix fe80::/64, but many definition says even fe80::/10 qualifies as link local address.
> Like on wiki:
> “In the Internet Protocol Version 6 (IPv6), the address block fe80::/10 has been reserved for link-local unicast addressing.[2] The actual link local addresses are assigned with the prefix fe80::/64.[6][note 2] They may be assigned by automatic (stateless) or stateful e.g. manual) mechanisms.”
>  
> So if we have an address as below, which does not match prefix condition, how an implementation should treat them.
> fe80:4888:208:ff8b:aa:21:0:2
>  
> process as global address surely not ??, but as link local , it does not qualify. Kindly suggest.

FE80::/10 are reserved for link-local addresses, so they should be treated as link-locals in your implementation.

RFC4291 does not say that link-local addresses must be assigned from FE80::/64. it states that the prefix must be followed by 54 bits of 0. I agree that RFC4291 is a little ambiguous, and that the link-local address format should be defined like the global unicast address in section 2.5.4.

cheers,
Ole