Re: [Dime] Call for WG adoption: draft-jones-diameter-group-signaling-01

Hi Tina,

I agree that the role of a proxy in group signalling has not been
explored in the current draft and appreciate your offer to work on
this aspect. Further comments inline.

On Wed, Apr 4, 2012 at 7:41 PM, Tina TSOU <Tina.Tsou.Zouting@huawei.com> wrote:
> Hi Jouni and Mark,
> The problem statement is valid and the solution can work in basic scenarios.
>
> However the solution may have some limit in roaming scenario.
>
> Consider a network having a WLAN AN (hosting a Diameter Client) requesting some 3G internet resources, visited network proxies and home network server as below:
>
> Client -------------- <Visited n/w proxy 1> ---------- {Home network server}
>         -------------- <Visited n/w proxy 2> ----------{Home network server}
>
> The session path can be established through either of the visited n/w proxies. For all the messages of same session, client can ensure that the session path through stateful nodes is maintained. The visited n/w proxies would require that the session path be maintained for offline charging etc.

In your example, I understand from "session path" that you're assuming
the client will ensure that the STR traverses the same visited n/w
proxy so that state is cleaned up in the appropriate proxy, right?

> In this scenario, if client uses group signalling method to terminate all sessions in a group using GSTR, only the proxy in the GSTR-GSTA path will be aware of session termination. Since there are no follow-up messages, there is no mechanism to let the other proxy know that the sessions are terminated.

If the client knows the session path for each session then it knows
that both visited n/w proxies need to receive the GSTR. However, if
the client sends the GSTR to both proxies then the home n/w server is
going to get two GSTR for the same group from the same origin host.
Yuck!

Since groups assignments are arbitrary, the client could create a
subgroup per session path and send the subgroup GSTR to the
appropriate proxy. Path failures would make the error handling very
complex though.

> This problem can be avoided in Server initiated group signalling cases (GRAR & GASR) as the PER_SESSION mode can be used for follow up exchanges.

It could also be avoided in the GSTR case. If the client knows that
the group termination will impact sessions that have session paths
split across multiple proxies then it MUST revert to per-session STR
signaling. However, I'd much prefer to solve this if we can.

> Thus the current solution has a limit if client uses group signalling method for session termination in roaming cases.
>

Agreed.

> I volunteer to work together with Mark to find a solution for this case.
>

Great!

> I'm NOT aware of any IPR in this area.
>

Me neither.

>
> Tina
>
>
>> -----Original Message-----
>> From: dime-bounces@ietf.org [mailto:dime-bounces@ietf.org] On Behalf Of
>> jouni korhonen
>> Sent: Sunday, April 01, 2012 12:20 PM
>> To: dime@ietf.org
>> Cc: dime-chairs@tools.ietf.org
>> Subject: [Dime] Call for WG adoption: draft-jones-diameter-group-
>> signaling-01
>>
>>
>> Folks,
>>
>> During the Dime WG meeting in Paris we decided to adopt draft-jones-
>> diameter-group-signaling-01
>> "Diameter Group Signaling" as a working group I-D. The I-D is an input for
>> the charter mile stone 'Protocol extension for bulk and group signaling'.
>>
>> This mail starts a one week verification for the adoption. If you have
>> strong concerns that the
>> draft-jones-diameter-group-signaling-01 is not appropriate as a _basis_
>> for the solution, then express your concerns on the mailing list by 8th
>> April.
>>
>> - Jouni & Lionel
>>
>>
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