Unused - give up now <draft-ietf-enum-unused-01.txt>

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Unused - give up nowltdraft-ietf-enum-unused-01.tx
tgt

• Lawrence Conroy
• Roke Manor Research
• lconroy_at_insensate.co.uk

This draft has been produced by Richard Stastny
(Richard.Stastny_at_oefeg.at), Lawrence Conroy
(lconroy_at_insensate.co.uk) and Jim Reid
(jim_at_rfc1035.com)
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Topics

• UNUSED Enumservice Specification
• Provisioning Issues

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Unused Enumservice Specification

• If encountered, this Enumservice means give up
  now
• If an ENUM client retrieves and processes this
  NAPTR, it should not try to place a call using
  any default behaviour
• It states that there are no implicit end points
  supported and a call attempt will fail.
• It is needed for ENUM Only number ranges
• Anyone trying to place a call to a number in such
  a range via the CSN shouldnt. Calls to these
  numbers REQUIRE an ENUM evaulation to find an end
  point.
• For normal ranges, trying via the CSN is
  reasonable if NXD is returned to an ENUM query.
  It isnt always.

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Provisioning Issues - I

• It may not be possible to provision a NAPTR into
  every unregistered domain associated with an
  E.164 number
• With variable length numbers, no one can predict
  which will be valid until each number is assigned
  to an end user.
• One solution - Organisation responsible for the
  Range provisions a Wildcard NAPTR in the Range
  Domain
• this will be returned to queries on unregistered
  numbers in the range (if provisioned correctly)

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Provisioning Issues - II

• Wildcards are Evil
• They are the loaded weapon left lying around for
  non-DNS specialists to play with, and this has
  predictable results
• They are hard to provision correctly to give the
  result intended. They are particluarly hard to
  provision in a large, deep hierachy (like ENUM)
  where domains are regularly being registered
• They are unsubtle they always give an answer. An
  ENUM client is misled into believing that the
  queried domain exists and gives this answer,
  whilst what it really means is by default, here
  is something that will be useful

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Provisioning Issues - III

• Alternatives to Wildcards
• Provision a NAPTR in the Enclosing (e.g. Range)
  Domain
• If an ENUM client (querying a number in this
  range) recieves a NXD response, then that
  response will show the enclosing domain in the
  authority section of the message
• The ENUM client could choose to make one last try
  - it could re-issue a NAPTR query in this
  enclosing domain (just below the zone cut). If it
  does, it would receive the Provisioned NAPTR, and
  can process this.
• The effect is similar to a Wildcard placed in the
  same domain, but without the unfortunate problems
  with mis-provisioning