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Re: Multiple Roots are "a good thing" - Karl Auerbach

  • From: Brett Frankenberger
  • Date: Mon Mar 19 00:59:52 2001

> We've seen through that.  Today we have a flourishing competitive telephone
> system filled with all kinds of commercial and technical offerings that were
> inconceivable during the days of "Ma Bell".

And yet the address -- NPA-NXX-NNNN -- remains centrally administered
and globally unique.  Would we be better off if the result of dialing
NPA-NXX-NNNN depended on which root translations table your phone
service provider happened to subscribe to.

> We routinely use directory services in a multiplicity of forms --
> telephone books published by local telephone companies or
> entrepreneurs, 411 services in various shapes and forms, web pages,
> or even on CD-ROMs (indeed a well known Supreme Court case involved a
> telephone directory published on CD-ROM).

You are confusing three distinct layers.  As perceived by the public,
we have:

(1) Directories, where you go to look up the "address" of what you are
searching for.  In the PSTN, we have indeed, as you note, had many
directories for years.  The same applies to the Internet, where there
have always (for some values of always) been multiple directory options
(Yahoo, Google, etc.).

(2) The Address, or a publically known, relatively constant, identifier
for a specific contact.  People expect addresses to be unique, and if
they aren't lots of things start breaking.  (This is the phone number
in the PSTN, and the Domain Name on the Internet.)

(3) Underlying routing information.  This is what makes the Address end
up where it's supposed to, and the public neither knows nor cares about
this.  (This is the IP Address in the Internet, and can be all sorts of
thigns in the PSTN.)

Comparisons between the PSTN and the Internet can be confusing because:
  (a) The PSTN has traditionally combined #2 and #3: my PSTN
address is NPA-NXX-XXXX, and the call is also typically routed based on
NPA-NXX-XXXX.  (This is changing, though, with Local Number
Portability, 800 portability, etc.).  This Internet, though, as kept #2
and #3 completely distinct.
  (b) The Internet "Address" (DNS name) has traditionally been somewhat
directory like -- www.companyname.com traditionally got you to company
name.  (But the PSTN address has generally been purely arbitrary, with
a relatively small number of 1-800-some-name-here exceptions.)

Many technical people equate "IP Address" with "Telephone Number" and
"DNS Name" with "Name in the Yellow Pages (or other directory)".  This
is presumably because they know IP is the routing layer and they assume
that the telephone number is the routing layer (sometimes it is,
sometimes it's more).  They then go one level up and assume DNS = Phone
Directory.  

But the public would never see it that way.  Most people don't even
know what an "IP Address" is.  To them, the DNS name is like the phone
number -- it's what people advertise, it's what people dial/type to
reach the company/person they want to reach; and Yahoo and the phone
book are comparable -- it's where consumers go when they want to find
the address of the entity they wish to reach.  Watch TV: you see:
   1-800-xxx-xxxx   www.xxx.com
Not:
   Under "xyz" in the White Pages or www.xxx.com
and not:
   1-800-xxx-xxxx   11.22.33.44

> These telephone directories are not published by any unified authority, there is
> no regulatory body sitting over them.  And we as consumers are not damaged or
> harmed by this.  And the telephone system continues to work just fine.

These telephone directories are also nothing like DNS.

> Yet, on the Internet there are those who wail and gnash their teeth at the
> thought that the Domain Name System, the Internet's "white pages" might have
> multiple points of entry.

DNS is nothing like the "white pages".  Yahoo and Google are like the
white pages.  DNS is like the phone number: it's the address used by
the general public.

> It bears repeating -- all that a root server does is to answer
> queries about how to find a server handling a TLD named in the query. 
> In other words, a root server only answers queries such as "Where do
> I find a server that contains the list of names in .com?".

That's basically what the central 800# routing database does:  it tells
the LEC with IXC to send the call to; the IXC then consults it's own
tables and finished routing the calls.

Would you also argue that we should have several 800# routing
databases, so that dialing an 800# gets you different places depending
on which 800# database offered your LEC the best deal?

Don't respond by saying that "of course phone numbers should be unique,
just like IP addresses are unique".  That completely misses the boat. 
>From the consumer perspective, phone # != IP address.  Phone # = DNS
name.  

Yes, in the Internet we can technically have multiple address spaces --
that is, multiple roots -- because we have cleanly divided routing (IP
addresses) from addressing (DNS name); and we can't technically have
multiple address spaces in the PSTN, because routing and addressing are
not cleanly divided.  But make no mistake about it: the fact that you
*can* partition the addressing layer without partitioning the routing
layer doesn't make it a good thing, and it doesn't make it any less
problamatic for users.

     -- Brett





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