Subject: [AAA-WG]: Need Accounting-Sub-Session-Id for Diameter Mobile IP accounting?

From: "Bob Kopacz" <[email-masked]>
Date: Fri, 5 Apr 2002 15:00:20 -0500

Hi Tony and Johan,

This is a preview of a possible issue.  I need to talk this over with
one of my cohorts who is more on top of this than I am, but with
16-April looming, I wanted to prime the pump.

The Diameter Mobile IPv4 draft talks about accounting, and mentions the
Acct-Multi-Session-Id AVP as the key that ties together all of the
accounting information for a MN's session, as it undergoes handoffs to
various FAs.

The draft doesn't mention the (probable) need for the
Accounting-Sub-Session-Id AVP, but maybe it should.

As I understand things (which may be wrong), here's where the
Accounting-Sub-Session-Id would come into play:

As the MN is handed off among FAs, each FA generates accounting with a
different Session-Id.  The HA and all the FAs generate accounting with
the same Acct-Multi-Session-Id.

But for a given FA, the MN's call may be handed off among various radio
nodes, each tied to this one FA.  The FA may want to generate the
accounting for the activity of each radio node.  The FA would do this by
treating each RN session as a subsession, and use the
Accounting-Sub-Session-Id to identify each RN session (since the
Session-Id and Acct-Multi-Session-Id wouldn't be changing).

I may not be using the terminology quite correctly, but I hope you get
my drift.

The 3GPP2 Wireless IP Network Standard document has a means to
report accounting for each RN (sub)session, so I am guessing that
Diameter Mobile IPv4 accounting wants to support this notion too.

Is it also possible that the HA may want to use the
Accounting-Sub-Session-Id to report accounting information for each FA
handoff?  That way, the HA's accounting and each FA's accounting could
be correlated.

Bob K.

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From: Johan Johansson <[email-masked]>
Date: Sun, 07 Apr 2002 15:00:01 +0000

>Diameter Mobile IPv4 accounting wants to support this notion too.
I suppose this would simply amount to making the 
Accounting-Sub-Session-Id optional in the AMRs for mobile ip accounting 
since the foreign network needs to implement this anyway. Making it 
mandatory would force networks for which this notion of "sub-handover" 
doesn't make sense to send a dummy avp.

I have to admit that I can't quite figure out why an operator would want 
to send it's internal handovers to another operator though, but if they 
really think they want to do that, who am I do deny them?

>handoff?  That way, the HA's accounting and each FA's accounting could
Well... I agree that this might provide an extra level of correlation. I 
am probably not the right person to judge its usefulness, but at the 
very least it seems *harmless*.

j