On Thu, 28 Jul 2005, JINMEI Tatuya / [ISO-2022-JP] ¿ÀÌÀãºÈ wrote:
1') Some people also wanted to indicate a stronger message of "do
not try to find it" for some networks in requirement 1.
Possible scenarios include bandwidth-sensitive networks (such
as 3G?) and the case where attacks of rogue DHCPv6 messages are
concerned.
[,,,]
3) Ability to do DHCP without having to configure routers
(e.g., by ignoring RA with M=0 and/or O=0 and invoking HCB and/or
ICB anyway)
[Note: this requirement may contradict requirement 1'. We'll need
to determine which one should be honored or whether there is an
intermediate compromise.]
[...]
Requirement 1 generally comes from some types of networks such as
cellular networks where network bandwidth or buttery consumption of
end stations is sensitive issues. I think people generally understood
the point and agreed that the appropriate mechanism for implementing
this is flag(s) in RAs.
However, opinions on the details appeared to vary, causing lots of
confusion. The major controversial points are probably summarized in
the succeeding sub-requirements:
- whether we need to prohibit the use of DHCPv6 more strongly and
explicitly (e.g., with a 'MUST NOT'), which corresponds to
Requirement 1'.
Let me try to offer a point here (and sorry if this is too early) why
I don't think a MUST NOT is not a requirement.
Specifically, I'm not sure if there are valid scenarios where these 3G
or other devices, which must conserve bandwidth, would implement
requirement 3, specifically in the interfaces associated with
conserved bandwidth? (This question could be asked differently: "Are
there networks where the network must tell that the hosts must
conserve bandwidth, otherwise the hosts don't know it?".)
It seems to me that those 3G vendors probably won't implement
requirement 3 (unless explicitly configured otherwise) at least on
their 3G interface, and then the whole problem goes away, because even
if the hosts implemented DHCPv6, they wouldn't use it on the interface
unless the network gives a sign they should. On the other hand, if a
vendor does implement it, and the user has to pay for the wasted
bandwidth, I guess the user is going to complain about it and it'll
get fixed.
I'm not sure if there are some cornercases wrt. the security argument
where this can't be as easily solved.
--
Pekka Savola "You each name yourselves king, yet the
Netcore Oy kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
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