: Issue: differences betweern 3GPP SIP usage and Diameter SIP document

I know I'm late with this wrt WGLC, but my colleague made a list
of differences between what's in the Diameter SIP document
and what 3GPP Cx interface does.

Please see the list below. I realize that a standard spec
may not match what someone else has been doing before
and there's bound to be extensions, things done in a better
way, etc.

However, I'd like circulate this list just to make sure that
we understand what these differences are, and to make
sure that these are intended differences and not accidental
differences that will make it harder for 3GPP to switch to
a IETF standard later (if they even want to, but that's
another discussion).

Bigger differences:

- DIAMETER_ERROR_USER_UNKNOWN is used when the User-Name is not
known in the draft, but in Cx when either the User-Name or the
public identity is not known.

- In the draft, the Authentication Pending flag is cleared in the
MAR. In the Cx, it is cleared in the SAR.

- In the draft, the SIP Server is stored in the MAR in some cases.
In the Cx, it is only stored in the SAR.

- In the PPR in the draft User-Data is mandatory,
in the Cx it is optional.

- In SIP-Auth-Data-Item SIP-Authentication-Scheme is mandatory,
in the Cx it is optional.

- SIP-User-Data is a Grouped with two mandatory AVPs in the draft,
in the Cx it is an OctetString that contains the XML data.

- In all responses in the draft Result-Code is mandatory,
in the Cx it is optional as an alternative to Experimental-Result

- In all draft commands there is a mandatory Auth-Application-Id,
in the Cx there is a mandatory Vendor-Specific-Application-Id.

Minor differences:

- In UAR and MAR in the draft User-Name is optional,
in the Cx it is mandatory. The draft specifies an error for when
the application requires a User-Name, but Cx uses a different
error.

- The draft states that it is not possible to return SIP Server and
capabilities in the same UAA. In the Cx it is done, but this may
be changed.

- There are two additional responses to MAR in the draft
(DIAMETER_SUCCESS_AUTH_SENT_SERVER_NOT_STORED and
DIAMETER_SUCCESS_SERVER_NAME_NOT_STORED)

- In the draft, it is possible to keep Diameter sessions and use the
STR and ASR.

- In UAR, Visited-Network-Identifier is optional in the draft and
mandatory in Cx.

- In RTR, User-Name is optional in the draft and mandatory in Cx.

- Format of the Charging Addresses is different.

- It is possible to generate the once in the Diameter client in the
draft.

- Authorization-Lifetime and Auth-Grace-Period are present in the draft
in MAA, SAA, PPR, LIA and RTA (are they needed in the RTA at all?).

- In the LIA in the draft, there are Redirect-Host, Redirect-Host-Usage
and Redirect-Max-Cache-Time, that are not in Cx.

- There is additional functions in Cx that are not in the draft, like
barring or implicit registration.

- In the handling of the MAR in the draft, it is stated that the Diameter
server keeps the address of the SIP server.