Re: [Dime] RFC 3588 - fixed positioned session-ID AVPs

Reword as necessary.

The reason that a "SHOULD" is followed by a "MUST" is because that seems
to be how diameter is defined, according to the previous posts.

The diameter protocol says "SHOULD" as far as positioning, but the BNF
may override the "SHOULD" with a "MUST".  It seems you are agreeing that
it is confusing. ;-)  This is why clarification is needed.

I think the wording that I provided is dead on, but as I stated, reword
as necessary.

--

David Lehmann

Ulticom, Inc.

856-787-2952

From: Victor Fajardo [mailto:vf0213@gmail.com] 
Sent: Wednesday, September 01, 2010 9:13 AM
To: David Lehmann
Cc: Glen Zorn; dime@ietf.org
Subject: Re: [Dime] RFC 3588 - fixed positioned session-ID AVPs

Its good to have some clarity, though the statement below probably needs
some re-org since SHOULD is followed with a MUST and theres a
conditional 'may' in between. Anyway, the statement maybe redundant
since each BNF already tells you where the session-id can be found ..

my 2 cents.

On Wed, Sep 1, 2010 at 8:55 AM, David Lehmann <dlehmann@ulticom.com>
wrote:

OK, BNF rules.    IMHO, this should be noted or clarified in section
8.8. e.g.

"When present, the Session-Id SHOULD appear immediately following the
Diameter Header. Further, the message BNF may mandate that the
Session-Id MUST be positioned immediately following the message header.
Indeed, all messages defined in this RFC require such a positioning.
(see Section 3)"

--

David Lehmann

Ulticom, Inc.

856-787-2952

From: Victor Fajardo [mailto:vf0213@gmail.com] 
Sent: Tuesday, August 31, 2010 4:25 PM 

To: David Lehmann
Cc: Glen Zorn; dime@ietf.org
Subject: Re: [Dime] RFC 3588 - fixed positioned session-ID AVPs

yes. the BNF sets the positioning/sequencing rules. it's a common
practice in BNFs to place session-id near the head to optimize msg
processing .. etc.

On Tue, Aug 31, 2010 at 3:22 PM, David Lehmann <dlehmann@ulticom.com>
wrote:

So you are stating that the Diameter protocol itself does NOT require
all session-ID AVPs to follow immediately after the message header, but
a message's BNF may require it?  

--

David Lehmann

Ulticom, Inc.

856-787-2952

From: Victor Fajardo [mailto:vf0213@gmail.com] 
Sent: Tuesday, August 31, 2010 2:21 PM 

To: David Lehmann
Cc: Glen Zorn; dime@ietf.org
Subject: Re: [Dime] RFC 3588 - fixed positioned session-ID AVPs

On Tue, Aug 31, 2010 at 1:54 PM, David Lehmann <dlehmann@ulticom.com>
wrote:

The existing text in 8.8 is contradicting the BNF.  

Which BNF though ? There maybe apps beyond 3588 that may not necessarily
put the session-id after the header in their BNF's. In that regard, the
existing text is not contradictory but is meant to be generalized
specially because it describes an AVP and is agnostic to any BNF.

my two cents,

victor

	I am suggesting text that agrees and supports the BNF.  

	If you don't want to modify the text to agree with the BNF, then
I suggest removing the existing text which contradicts it.

	--

	David Lehmann

	Ulticom, Inc.

	856-787-2952

	From: Victor Fajardo [mailto:vf0213@gmail.com] 
	Sent: Tuesday, August 31, 2010 11:52 AM
	To: David Lehmann
	Cc: Glen Zorn; dime@ietf.org
	Subject: Re: [Dime] RFC 3588 - fixed positioned session-ID AVPs

	Hi David,

	On Tue, Aug 31, 2010 at 10:37 AM, David Lehmann
<dlehmann@ulticom.com> wrote:

	Glen,

	That is not what the spec says.  At least, the wording is not
clear and, IMHO, is misleading.  In which "some message" can the
session-id AVP be in any position?

	It seems to me that the wording in section 8.8 should be:  "When
present, the Session-Id MUST appear immediately following the Diameter
Header (see Section 3)."

	As Glen has mentioned, the BNF dictates the positioning of the
AVP. If you add this text you are adding new rules beyond the BNF.

	regards,

	victor

		--

		David Lehmann

		Ulticom, Inc.

		856-787-2952

		From: Glen Zorn [mailto:gwz@net-zen.net] 
		Sent: Tuesday, August 31, 2010 9:54 AM
		To: David Lehmann
		Cc: dime@ietf.org
		Subject: RE: [Dime] RFC 3588 - fixed positioned
session-ID AVPs

		David Lehmann [mailto://dlehmann@ulticom.com]
<mailto:[mailto://dlehmann@ulticom.com%5d>  writes:

		Hello,
		Hello.
		In RFC 3588 (and 3588bis), messages with session IDs are
defined with the session ID AVPs with a fixed position which is
immediately following the header. (e.g. section 8.3.1)  
		Yes.
		However, this is in contradiction with section 8.8 which
states, "When present, the Session-Id SHOULD appear immediately
following the Diameter Header (see Section 3)."
		No.
		By using "SHOULD", the spec is stating that the
session-ID AVP could be in any position in the message.

		No, it is stating that the AVP could be in any position
in some message.  The syntax of the existing messages in RFC 3588 is
defined by the associated BNF and in those messages the Session-Id AVP
must immediately follow the Diameter header.

		Hope this helps.

		 ~gwz

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