Re: Policy of IPv6 DNS Discovery

[Pekka Savola <pekkas@netcore.fi>]

On Mon, 4 Aug 2003, Masataka Ohta wrote:
> > At 01:35 AM 8/4/2003, Jaehoon Paul Jeong wrote:
> 
> > >I think, I did my best to appeal the necessity of RA-based DNS Discovery, 
> > >although I could not express my opinions well enough because of the limitation of Non-English speaker.
> > 
> > Your interest is clear,
> 
> And it is also clear that his case does not need RA-based DNS
> discovery, as was pointed by two of us.
> 
> In mobile case, mobile hosts need constant DNS service. It is NOT
> acceptable that the mobile hosts try to find DNS server at
> foreign environment sometime successfully and sometimes not
> that DNS service MUST be bundled and share fate with HA service,
> which should be configured simultaneously.
[...]

There are two cases here:

 1) "mobile hosts which use Mobile IP"

 In this case, what you say may rather close to the mark.  However, note 
that if a mechanism to find DNS service is commonplace, hosts would have 
more success in finding it -- and the point of not getting it would be 
moot.  

 Moreover, the DNS service located at the home network could be the "last 
resort" service, to be used when no other DNS servers are found in foreign 
network(s).  Depending on where your home agents are (e.g. across the 
globe, 300 ms RTT away), being able to optimize to use the closer DNS 
servers would be desirable, I think.

 2) "mobile hosts without Mobile IP"

A case of this is e.g. a laptop which just plugs in networks here and
there (e.g. IETF meetings) and is not concerned on connection survability,
i.e. doesn't really have a home agent or home network (in Mobile IP
terms).  Such hosts typically require nothing else of the foreign networks
they use than DNS resolution.  They already have (in most cases!)
sufficient clock (for DNSSEC, if used), don't want DNS search path to
point to some local operator's domain because they don't care about it,
etc.

Seems like there may be some cases where DHCP-less operation could indeed 
be useful.

However, if implementing DHCP-lite or such was simple and straightforward 
enough, requiring very little effort, that just *MIGHT* be the way to go 
-- because it will have to be implemented *anyway* to cater for the needs 
of the other cases where configuring more than just the DNS server is 
needed.

I haven't really made up my mind whether DHCP-lite fulfills those
criteria.

-- 
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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