I certainly agree that the benefit of the simplicity of this rule is very desirable. However, this rule may be too restrictive. I am worried that there might be cases where it is desirable to send a packet to a (on-link) global address using a link-local address or ULA. Straight off the top of my head, I can think of a solicited RA. This message must use as a source address the router's link-local address and as a destination address the address of the node that sent the RS, that may very well be global.
----- Original Message ---- From: Fred Baker <[EMAIL PROTECTED]> To: Gabi Nakibly <[EMAIL PROTECTED]> Cc: Pekka Savola <[EMAIL PROTECTED]>; ipv6@ietf.org; Iljitsch van Beijnum <[EMAIL PROTECTED]> Sent: Tuesday, March 18, 2008 2:33:15 PM Subject: Re: RFC3484 destination address selection rule 2 is buggy On Mar 18, 2008, at 5:10 AM, Gabi Nakibly wrote: > Determining whether the destination address is in the zone of a > source address can be tricky. However, it is fairly easy in the > common case where the source address is link-local and the > destination address is global. If the latter is not on-link, than > it is not in the zone of the link-local source address and this > source address should not be included in the candidate set. If the > above rule will be applied in the scenario of http://tools.ietf.org/ > html/draft-ietf-v6ops-v6onbydefault-03, the candidate set of the v6 > address will be empty and therefore it will be avoided by > destination address selection rule 1. Speaking for myself, there is a simpler rule in that special case that imght be instructive in the ULA case. There is no sense in using a link-local address as a source address unless one is sending to someone on the same LAN. Hence, there is no sense in suing a link-local address as the source if one cannot also use one in the destination. Similarly, there is no sense using a ULA source address unless the destination is in the same ULA. If the destination is a global address it might or might not be able to reply, but the sender can't tell. Hence, in sender address choice: - use a link-local source address if and only if the destination is a link-local address - use a ULA source address if and only if the destination is a ULA in the same prefix - otherwise, use a global address ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
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