Subject: RE: 3gpp-analysis: DNS over v4 if availablen

From: <[email-masked]>
Date: Tue, 18 Nov 2003 16:16:29 +0200

Pekka, 

I don't think that making that statement adds any value. Just because IPv4 and IPv6 PDP contexts are separate and we don't assume that both of them are simultaneously used by an application. E.g. keeping IPv4 PDP context always activated (just in case, if DNS queries are needed) is not good usage of nw resources.

A basic application (for example HTTP browsing) uses only one PDP context (v4 or v6), but there will be applications using more than one PDP context (both primary and secondary contexts), but that's another story...

Cheers,
	 -Juha-

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On
Behalf Of ext Pekka Savola
Sent: 17 November, 2003 13:18
To: [email-masked]
Subject: 3gpp-analysis: DNS over v4 if availablen

Hi,

Relating to the previous "Need for UE <-> 3GPP configuration" 
configuration issue (closed now), I'd maybe augment the text:

    DNS server addresses typically also need to be configured in the
    UE. In the case of IPv4 type PDP context, the (IPv4) DNS server
    addresses can be received in the PDP context activation (a control
    plane mechanism). Same kind of mechanism is also available for
    IPv6: so-called Protocol Configuration Options Information Element
    (PCO-IE) specified by the 3GPP [3GPP-24.008]. It is also possible
    to use [DHCPv6-SL] or [RFC3315] and [DHCP-DNS] for receiving DNS
    server addresses. The authors note that the general IPv6 DNS
    discovery problem is being solved by the IETF dnsop Working Group.
    The DNS server addresses can also be received over the air (using
    SMS), or typed in manually in the UE.

.. by adding a sentence at the end:

                                           Note that as long as IPv4
    PDP context is active, DNS lookups can also be done over IPv4
    transport.

.. just to highlight the fact that w/ dual-stack UE deployment, not having
v6 DNS is not necessary a big deal (yet!)

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

---

From: Pekka Savola <[email-masked]>
Date: Tue, 18 Nov 2003 16:29:35 +0200 (EET)

On Tue, 18 Nov 2003 [email-masked] wrote:
> I don't think that making that statement adds any value. Just because
> IPv4 and IPv6 PDP contexts are separate and we don't assume that both of
> them are simultaneously used by an application. E.g. keeping IPv4 PDP
> context always activated (just in case, if DNS queries are needed) is
> not good usage of nw resources.

It certainly adds value if you don't want to implement a mechanisms to 
autoconfigure v6 DNS resolvers, or don't know which way to adapt to do so.

So, IMHO, it's clearly useful to state that as long as both PDP contexts 
are open, DNS lookups for v6 addresses work just fine.

I'm not sure whether any vendor or operator would like to go down that 
route, but it seems like a possible alternative.