Subject: Re: Flagging non-ASCII in domain names

From: Dan <[email-masked]>
Date: Sun, 20 Aug 2000 12:42:15 +0200 (MET DST)

> So far, the IPNG and DNSEXT working groups look like they'll be making
> the use of EDNS mandatory for IPv6 and DNSSEC (respectively).  As such,
> it would appear that in order to work and play well in the future
> support for EDNS is necessary.

Very good, when?
If all TLD servers and most of the next level down can support EDNS
by summer 2001, then I see no problems. Otherwise there will be because I
expect non-ASCII domain names will be started to be used a lot by then.
Long before DNSSEC will be used generally.

> 
> > The "old world" servers will
> > return a failure when queried using EDNS resulting in the client
> > to have to retry the query without EDNS. 
> 
> As I believe I mentioned previously, the only EDNS-using resolver that
> I'm aware of (the one in BINDv9) maintains state about the servers that
> it has talked to regarding that server's support for EDNS.

I can see that a DNS server can maintain state about it, but not client
resolver libraries (except within one instance of a running software).
So every client doing a lookup will start fresh without any state and
will have the overhead. This can quite well be fixed, if you control the
DNS server the client do recusive lookups through. In that case you
can upgrade it to an EDNS aware server and the server can do the caching.
If you cannot change the DNS server, you will have a big overhead.
While things like DNSSEC would only need ENDS if DNSSEC was used, for non-ASCII
names every query must use EDNS to flag that the client can handle non-ASCII.

Does anyone have a feeling how quickly all TLD servers and most of the ones
one level down will handle EDNS? If if will happen quickly, I see no problem
in using ENDS.

Does anybody have any comments on using the last free bit or using for example
the AA bit as an incoming flag bit? Are there really any problems with this,
or is it just that everybody want to go EDNS?

   Dan

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From: Edward Lewis <[email-masked]>
Date: Sun, 20 Aug 2000 18:36:49 -0400

>or is it just that everybody want to go EDNS?

If we are to do something in a short amount of time, we should do it in a
way that is most amenable to being backed out.  Therefore, I'd urge any
work towards  iDNS to make use of EDNS and not (re)use the bits of the
aboriginal header.

Also, EDNS is designed to allow enhancements to DNS, so it seems like
extending towards iDNS would naturally use EDNS.

>DNS server the client do[es] recusive lookups through. In that case you

A stub resolver does not necessarily have to contact one and only one
recursive name server.  If you are concerned that your organization's name
server(s) are not iDNS aware, you can run your own non-authoritative server
that is and use it to answer your own questions.  However, you are
out-of-luck if you have a device (e.g., a firewall) that prevents the
transfer of DNS traffic between you and the Internet.

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Edward Lewis                                                NAI Labs
Phone: +1 443-259-2352                      Email: [email-masked]

"It takes years of training to know when to do nothing" - Dogbert

Opinions expressed are property of my evil twin, not my employer.

---

From: "Eric A. Hall" <[email-masked]>
Date: Sun, 20 Aug 2000 19:38:01 -0700

Edward Lewis wrote:
> >Does anybody have any comments on using the last free bit or using
> >for example the AA bit as an incoming flag bit? Are there really any
> >problems with this, or is it just that everybody want to go EDNS?
> 
> If we are to do something in a short amount of time, we should do it
> in a way that is most amenable to being backed out.  Therefore, I'd
> urge any work towards  iDNS to make use of EDNS and not (re)use the
> bits of the aboriginal header.

One other possibility is using the bits from the length field of the
domain name label data type. Currently the two defined uses of the first
two bits from this field are 00 for data and 11 for compression. Neither
01 or 10 are used for anything to my knowledge.

It may be workable to define one of those bit patterns so that they
indicate some sort of international encoding. The upside to this approach
is that it is pretty simple to code support for. The downside is that it
would have to be a fixed character set, so it probably wouldn't be an
exceptionally robust solution, but instead would be "less limited".

If full encoding of double-byte data is required/desired, I would think
EDNS would be the most viable option.

-- 
Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/

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From: Marc Blanchet <[email-masked]>
Date: Mon, 21 Aug 2000 07:11:08 -0400

>01 or 10 are used for anything to my knowledge.

01 is used for edns. From RFC2671:

3 - Extended Label Types

3.1. The "0 1" label type will now indicate an extended label type,
      whose value is encoded in the lower six bits of the first octet of
      a label.  All subsequently developed label types should be encoded
      using an extended label type.

>indicate some sort of international encoding.

10 has been proposed by one group
(http://www.ietf.org/internet-drafts/draft-ietf-idn-dnsii-mdnp-00.txt)

>The upside to this approach

one draft talks about using edns
  (http://www.ietf.org/internet-drafts/draft-ietf-idn-idne-01.txt)

Marc.

Marc Blanchet
Viagénie inc.
tel: 418-656-9254
http://www.viagenie.qc.ca

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From: Paul A Vixie <[email-masked]>
Date: Mon, 21 Aug 2000 08:33:23 -0700

> 01 is used for edns. From RFC2671:

and 10 was used by peter koch's local compression, which was killed in nov99.

> >indicate some sort of international encoding.

it's unlikely that 10 will be assigned now that edns is a proposed standard.

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From: "Martin J. Duerst" <[email-masked]>
Date: Wed, 23 Aug 2000 15:44:30 +0900

>exceptionally robust solution, but instead would be "less limited".

Using more than a single character set, while still not fully ruled
out, would create many different problems and would decrease, not
increase, robustness. So using just a flag is okay, the question
is mainly which one.

Regards,   Martin.