VERMOUTH for MARTINI SIP MARTINI Variant of 'Event-package for Registrations

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VERMOUTH for MARTINISIP MARTINI Variant of
'Event-package for Registrations for Managed
Open-ended Username Target Handling
(VERMOUTH)draft-kaplan-martini-vermouth-00

• Hadriel Kaplan

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The Problem

• GIN gives us reg-event for PBX side, but
• Its also useful for Martini in the SSP side
• For systems to learn when the IP-PBX is
  registered and its path/contact info
• For the IP-PBX et al to verify/learn what AoRs
  the SSP associates with it
• For SSP to Notify IP-PBX of adds/removes
• But the usernames may be open-number-plan or
  Local Numbers
• Each actual possible username is unknown to SSP
• And it may be a very big list if it is known

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Mismatched provisioning a real problem

• When SSP and PBX AoRs dont match, bad things
  happen
• Calls fail to reach PBX
• Calls loop (badly)
• Sometimes the error is caught quickly, but
  usually not until its actually called
• It takes time to troubleshoot, and reducing that
  time saves money and customer frustration

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Possible Solutions

1. Use reg-event, define a syntax to handle
   open/wildcard usernames for AoRs in reg-event
2. Subscribe to something new (not reg-event) to
   learn about provisioned AoRs
3. Use PUBLISH to push from SSP to PBX

VERMOUTH currently does 1, but its tempting to
go for 2
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Proposed Solution in Draft

• Define a new Bulk-AoR for reg-event
• Uses new range user param to indicate range
• E.g. sip12345678range0-9(1,4)_at_example.com
• bulk-aor-user user "range" expansion
• expansion exp-char-set exp-char-count
• exp-char-set digit-char-set / any-char-set
• digit-char-set dsc-begin "-" dsc-end
• dsc-begin DIGIT
• dsc-end DIGIT
• any-char-set "."
• exp-char-count "(" exp-min "," exp-max ")"
• exp-min DIGIT
• exp-max DIGIT

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Why not regex?

• Some common regex characters are not allowed in
  SIP URIs and would need to be escaped
• , , , ,
• Regex patterns are good for figuring out if a
  given string matches the pattern, but not what
  all possible strings matching it are
• E.g., you can tell if 12345 matches, but not that
  12346 and 1234567 also match
• In other words, its hard to tell if the SSP
  thinks more usernames belong to the PBX than the
  PBX does
• There are numerous patterns which match the same
  strings

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Example reginfo XML

• lt?xml version"1.0"?gt
• ltreginfo xmlns"urnietfparamsxmlnsregin
  fo"
• xmlnsxsi"http//www.w3.org/2001/XMLSch
  ema-instance"
• version"0" state"full"gt
• ltregistration aor"sip12345678range0-9
  (1,4)_at_example.com"
• id"as9" state"active"gt
• ltcontact id"76" state"active"
  event"registered"
• duration-registered"7322"
• q"0.8"gt
• lturigtsip192.1.2.3bnclt/urigt
• lt/contactgt
• ltcontact id"77" state"terminated"
  event"expired"
• duration-registered"3600"
• q"0.5"gt
• lturigtsip192.4.5.6bnclt/urigt
• lt/contactgt
• lt/registrationgt
• lt/reginfogt

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Subscribing

• The current 00 draft has the SSP process
  Subscribes to the AoRs, but GIN now does the
  opposite normal Subscribes go to the PBX
• GIN wins, so VERMOUTH draft will change
• The question is what URI syntax to use for the
  PBX to subscribe to the SSP for the data
• E.g., sippbx1_at_ssp.combulk

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Choosing Option-2

• Its tempting to define a new bnc-reg-event
  package
• Can be made more efficient, because all AoRs
  share same contact/path info
• Dont need to create a Bulk-AoR format as a URI
  just do it as explicit XML
• New package name lets SSP route it to appropriate
  server in SSP

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Questions

• Is this a problem worth solving?
• Is there interest to do so in this WG?

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Open Issues
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Bulk AoR format

• Should we just use regex and escape illegal
  characters?
• Since the URI user type is of a specific type,
  should we create a new user param enumeration
  value?
• E.g., userbulk similar to userphone

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What about email-style AoRs?

• Currently VERMOUTH includes this in the range
  syntax
• E.g., sip.(1,9)_at_ssp.com
• But in practice they probably wont work this way
  and would need to be enumerated, possibly leading
  to large sets
• And reg-events XML schema is inefficient for
  that case