> -----Original Message----- > From: Dr. Subrata Goswami [mailto:[EMAIL PROTECTED]] > Sent: Saturday, June 01, 2002 8:46 PM > Cc: [EMAIL PROTECTED]; 'IPng Working Group' > Subject: RE: [mobile-ip] RE: RFC 2462 DAD optimization > > I am just curious about what are the technical differences between a > link-local address and a subnet-local address.
A subnet can cover multiple links, whenever you have some type of RA/ND proxying going on. A link-local address is unique only within a single link, and is never proxied. Today fe80::/10 and ffx2::/16 addresses are defined as being link-local. This means that two links in the same subnet can reuse the same link-local addresses. Ffx3::/16 is a subnet-local multicast range. There is no subnet-local unicast range today. Charlie is arguing that he would like to see fe80::/10 redefined as the "subnet-local" unicast range, rather than the link-local unicast range, which means that a multilink subnet router (of which a home agent is one special case) would be required to proxy ND for link-local addresses. (Personally, I think it's way too late to define fe80 as subnet-local.) Today, a multilink subnet router would have no need to do that, other than the problems resulting from anyone not doing DAD on every address - which does not appear to be a problem today. See draft-ietf-ipngwg-scoping-arch-03.txt and draft-thaler-ipngwg-multilink-subnets-02.txt for more information. > I agree with Dave that, doing a DAD for "link-local" type of post-fix > address is a unnecessary restriction. > > 1. There might be global addresss manually configured with the same > post-fix but with different pre-fix as the link-local address of a > node. What would HA do if a node like that moves into its territory ? > 2. For 64-bit post-fix it would render 2**64 perfectly good addresses > useless. > > Subrata -Dave -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
