JINMEI Tatuya / 神明達哉 a écrit :
At Wed, 18 Feb 2009 21:54:37 +0100, Alexandru Petrescu
<[email protected]> wrote:
- prefix P::/56 with L=1, A=0, and - prefix P::/64 with L=0, A=1
if the receiving host is fully compliant with RFC4861 and 4862.
Excuse my ignorance but I don't see why putting two prefixes in the
RA when one is sufficient with A=1 and L=1.
Because the specification is written that way. From a pure technical
point of view, we could have introduced a new rule, e.g., "if the
length of a prefix with A=1 is less than 128 - length of IID, the
host should continue configuring an address with the prefix and the
IID, filling in the remaining bits with 0".
Technically that may sound absolutely wonderful, but I agree maybe more
motivation is needed.
My whole point is that it's not worth the time and process overhead
to consider introducing such an additional extension at this stage
without a strong reason, and 'we could do it, why not' is (IMO) way
too weak a reason.
Well, I agree. This is not because we could do it.
Were it said a RA prefix for Ethernet SLAAC could be shorter than /64,
there could be some advantages for: administrative headaches, saving
wireless bandwidth, easier DHCPv6 PD, avoid prefix-per-host address
waste, motivate design of shared multicast-capable links (on which ND
and others depend so largely), replace some proxy ND bridges with
routers, and maybe more.
Alex
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