[martini] De-registration and GIN

[David Hancock <[e-mail]>]

I have a couple of questions on de-registration and GIN.

RFC 3261 Section 10.2.2 "Removing Bindings" provides a way to remove all contacts bound to a registered AOR.

Here's the text...

   The REGISTER-specific Contact header field value of "*" applies to
   all registrations, but it MUST NOT be used unless the Expires header
   field is present with a value of "0".

      Use of the "*" Contact header field value allows a registering UA
      to remove all bindings associated with an address-of-record
      without knowing their precise values.

Question-1: How is this procedure applied when the AOR-to-contact binding was established using GIN (RFC 6140)? Does the sending PBX include "bnc" in the Contact header? I assume it does not, since "bnc" is a URI parameter and there is no actual contact URI in this case.

On a related topic, RFC 6140 section 5.2 clarifies the interaction between explicit and GIN registration with the following text...


   Although the SSP treats this registration as a number of discrete

   rows for the purpose of re-targeting incoming requests, the renewal,

   expiration, and removal of these rows is bound to the registered

   contact.  In particular, this means that REGISTER requests that

   attempt to de-register a single AOR that has been implicitly

   registered MUST NOT remove that AOR from the bulk registration.  In

   this circumstance, the registrar simply acts as if the UA attempted

   to unregister a contact that wasn't actually registered (e.g., return

   the list of presently registered contacts in a success response).  A

   further implication of this property is that an individual extension

   that is implicitly registered may also be explicitly registered using

   a normal, non-bulk registration (subject to SSP policy).  If such a

   registration exists, it is refreshed independently of the bulk

   registration and is not removed when the bulk registration is

   removed.

So basically, an explicit de-registration should not impact bindings established via GIN, and vice versa.

For example, PBX sip:[e-mail] serving 4 E.164 numbers uses GIN to bind its extension AORs to two different contact addresses, thus creating the following bindings...

8 GIN bindings...
sip:[e-mail] --> sip:[phone]@192.158.10.1
sip:[e-mail] --> sip:[phone]@192.158.10.1
sip:[e-mail] --> sip:[phone]@192.158.10.1
sip:[e-mail] --> sip:[phone]@192.158.10.1

sip:[e-mail] --> sip:[phone]@192.158.20.1
sip:[e-mail] --> sip:[phone]@192.158.20.1
sip:[e-mail] --> sip:[phone]@192.158.20.1
sip:[e-mail] --> sip:[phone]@192.158.20.1

Plus a UA explicitly registers one of the E.164 numbers to two different contact addresses to create the following additional bindings...

2 explicit bindings...
sip:[e-mail] --> sip:192.158.30.1
sip:[e-mail] --> sip:192.158.40.1

Now the PBX or UA can use the "*" construct to delete all of their respective bindings.


[1] from the PBX

   REGISTER sip:sp.com SIP/2.0

   To: <sip:[e-mail]>

   From: <sip:[e-mail]>

   Proxy-Require: gin

   Require: gin

   Supported: path

   Contact: *

   Expires: 0


[2] from the UA

   REGISTER sip:sp.com SIP/2.0

   To: <sip:[e-mail]>

   From: <sip:[e-mail]>

   Contact: *

   Expires: 0

On receiving [1], the SP/registrar removes the 8 GIN bindings without touching the explicit bindings.
On receiving [2], the SP/registrar removes the 2 explicit bindings without touching the GIN bindings.

Since the Contact header doesn't contain a "bnc" parameter in this case, the registrar behavior is governed by the presence/absence of the "gin" option-tag in the Require header.

Question-2 - does the example align with RFC6140?

Thanks
David Hancock