Scott, You are correct. Note IANA assigns address blocks defined in some RFC and indeed for the IPv6 link-local address RFC 4291 is referenced by IANA. See section 2.4 of RFC 4291 that includes this line.
[Link-Local unicast 1111111010 FE80::/10 2.5.6] Hemant -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Scott Schmit Sent: Saturday, March 05, 2011 9:50 AM To: [email protected] Subject: Re: Question about the link-local addresses On Sat, Mar 05, 2011 at 10:59:25AM +0800, Yu Hua bing wrote ipv6: > >RFC4291 > > Link-Local addresses are for use on a single link. Link-Local > > addresses have the following format: > > | 10 | > | bits | 54 bits | 64 bits | > +----------+-------------------------+----------------------------+ > |1111111010| 0 | interface ID | > +----------+-------------------------+----------------------------+ > > I have a question: If the front 10 bits of one IPv6 address is FE80 and the middle 54 bits is not zero, is it link-local address? Increasing the puzzle, while the text above would imply that if the middle 54 bits are not zero, it's not link-local, but if you look at http://www.iana.org/assignments/ipv6-address-space/ipv6-address-space.xm l, you will see that IANA has allocated fe80::/10 to "Link Local Unicast". This lends weight to the interpretation that it's the 10 bits that makes it a link-local address. Otherwise, they should only have allocated fe80::/64 for that purpose. I'm leaning toward the interpretation being "if you're in fe80::/10, you're link local, but addresses outside fe80::/64 are reserved." -- Scott Schmit -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 -------------------------------------------------------------------- -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
