Subject: (IPng 7056) Qeustion on initial IPv6 Sub-TLA ID Assignments

From: Ramin Sepehr Rad <[email-masked]>
Date: Wed, 13 Jan 1999 16:12:00 -0500 (EST)

A collegue of mine brough to my attention that some notations used in the 
draft on "Initial IPv6 Sub-TLA ID Assignments" is a little bit confusing. We
hope we can get a clarification on this.

His question is followed. You may email him directly, [email-masked], but
please CC me as well.

Thanks,
-ramin

---------- Forwarded message ----------
Date: Wed, 13 Jan 1999 16:05:48 -0500 (EST)
From: Shane Kerr <[email-masked]>
To: Ramin Sepehr Rad <[email-masked]>
Subject: Initial IPv6 Sub-TLA ID Assignments

We were figuring out the actual IP ranges from the IPv6 draft,
<draft-ietf-ipngwg-iana-tla-01.txt>, and we thought the initial
assignments of the sub-TLA ID's was a bit confusing.  Here's an excerpt
from section 3.0 in the draft: 

   As specified in [TLA-RULES] assignments of Sub-TLA ID's will be done
   in blocks.  The initial assignment of Sub-TLA ID's to registries will
   be in blocks of 64 Sub-TLA ID's.  These assignments are as follows:

      Binary            Range (Hex)       Assignment
      ----------------  ---------------   -------------------
      0 0000 00XX XXXX  0x0000 - 0x003F   IANA
      0 0000 01XX XXXX  0x0040 - 0x007F   APNIC
      0 0000 10XX XXXX  0x0080 - 0x00BF   ARIN
      0 0000 11XX XXXX  0x00C0 - 0x00FF   RIPE NCC

      Where "X" indicates "0" or "1".

This is all well and good, until you consider where these bits lie in an
IPv6 address.  Here's the anatomy, grouped by hex digit:

FFFT TTTT TTTT TTTT : SSSS SSSS SSSS SNNN : NNNN NNNN NNNN NNNN :

I've noted Format Prefix by "F", TLA ID by "T", Sub-TLA ID by "S", and 
NLA ID by "N".  The Sub-TLA bits start on the left boundary of the fifth
hex digit, immediately after the first colon.  Given this reality, I would
prefer if the assignments were listed as follows:

      Binary            Range (Hex)       Assignment
      ----------------  ---------------   -------------------
      0000 000X XXXX X  0x0000 - 0x01FF   IANA
      0000 001X XXXX X  0x0200 - 0x03FF   APNIC
      0000 010X XXXX X  0x0400 - 0x05FF   ARIN
      0000 011X XXXX X  0x0600 - 0x07FF   RIPE NCC

      Where "X" indicates "0" or "1".

The actual prefixes of the initial assignment are:

  2001:0000::/23  IANA
  2001:0200::/23  APNIC
  2001:0400::/23  ARIN
  2001:0600::/23  RIPE NCC

I understand that using this notation might cause some confusion, since
the hex ranges don't parse normally, but I think it will be more helpful
in the long run.  In fact, I'd prefer to do away with the hex ranges
altogether than go forward using bit values that don't map into the IPv6
numbers properly.

Shane Kerr <[email-masked]>
Software Engineer
American Registry for Internet Numbers

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