Subject: RE: on NAT-PT

From: "Thakur, Anand" <[email-masked]>
Date: Tue, 10 Dec 2002 16:06:35 +0530

senthil sivakumar wrote.

	> >i agree.
	> >  what if we do the following:
	> >whatever the incoming response, the dns_alg will forward 2
responses to the
	> >client:
	> >1)if the response is v4 only, then the dns_alg along with the v4
response
	> >will forward a mapped v6 response.

	>How does the dns alg know that there won't be a v6 response for the
same query.

	I guess there should be a time out for this. i.e after waiting for a
pre-determined amount of time (which will of course be implementation
dependent)the DNS-ALG should assume that a V6 response is not going to come
and forward the mapped v6 response along with the v4 response.

	> >2)vice-versa if the response is v6 only
	> >3)if 2 responses are received then forward them both to the
client

	> >a simple functionality in the client may be able to discard the
not-required
	> >result. though this will require a bit of effort on the part of
the dns_alg,
	> >but is nothing as compared to the effort that excessive
translation will
	> >cause.

	>Most of the clients only care about the first response and discard
others. 
	>Now you
	>are suggesting that the client to be changed which does not sound
very 
   >appealing.

   The only problem here may be changing the vast number of IPV4 clients.
since deployment of    v6-only and/or dual-stack clients is still in the
pipeline, modification may not be that big a task especially considering the
benefits that may be reaped out of this.in fact, modifying ipv4 clients may
not be required by making sure that the dns-alg forwards the v4 reply first,
so that if the client, if v4, accepts this response and discards any further
responses (as it will normally do).

regards
Anand Thakur
HCL Perot Systems
A-14 Sector-57,Noida
tel ext. - 3257
mobile:9811748512