RE: 3gpp-analysis-07: (semi-)editorial issues

[Pekka Savola <pekkas@netcore.fi>]

Inline to one remaining bigger issue..

On Fri, 19 Dec 2003 juha.wiljakka@nokia.com wrote:
> > Only thing that somehow worries me is activating PDP contexts that
> > may not be needed, i.e. extra usage of network resources. Should we
> > add some note on that, e.g. draft-elmalki-sipping... states that
> 
> I note that there are two cases here:
>  1) if you desire to operate the node as much in v6-only mode as 
> possible (not opening v4 PDP context unless you have to), or
>  2) if you desire to operate the node as much in v4-only mode as 
> possible (not opening v6 PDP contexts unless you intend to use apps 
> which use v6).
> 
> Which problem (or both?) are you worried of at this point?  
> 
>  JW: In my opinion, this sentence can be problematic: "it may also
> make sense to open both PDP contexts in advance, before they are
> used, because the activation of a context may take a relatively long
> time."  It can lead to a situation in which we have activated
> hundreds of thousands extra, unused PDP contexts in the network and
> this is not good from network resource usage point of view. PDP
> context usage is quite much defined by used applications and I think
> we shouldn't write "open both types of PDP contexts in advance"
> recommendation. My recommendation is to leave the PDP context
> activation policy decided by the implementers / application
> developers.

I think the wording above, "may also make sense", seems informative 
enough, not forcing the operators/vendors behave like suggested if 
they have good reasons.

But that aside, I think it may make sense to discuss one assumption 
different people seem to be making in a different fashion.

When you say "used applications", what are you referring to?  The 
whole IMS subsystem, some IP applications installed on a node (SSH 
client, web browser, ftp client, peer-to-peer application, etc.)?

These bring on two points which have been raised in the past: PDP
context activation takes time (maybe like 5 seconds or so, at least?), 
so activating it when trying to contact a peer could lead to long 
waiting and unsatisfied users.  Similarly, with some applications, it 
is not known in advance which kind of peer nodes it will connect to 
(e.g., the client apps above).  IMS subsystem is an exception here: 
you always know it's v6-only.  Maybe you have that in mind?

So, if the UEs include (or could include) apps like SSH/telnet
clients, web browsers, etc. (especially if those are not proxied by
the 3GPP operator), it might make sense to open PDP contexts in 
advance (or at the latest when the application is started).

Some of this justification should probably go in the document in some 
form.

> Ok, then maybe reword to something like ? :
> 
>                                               IPv6 PDP contexts 
> should be used even if that meant IPv6-in-IPv4 tunneling would be 
> needed in the network (see section 3.2 for more details).  Note 
> that this is transparent to the UE.
> 
>  JW: Looks quite ok. Maybe changing used -> preferred. 

Fine with me.

> Next steps with 3GPP Analysis: because other tasks have kept me very
> busy during last couple of weeks, I will make revision -08 in
> January (I try to do that by mid-January). There are still some
> comments that I need to go through and reply to on the mailing list.

Thanks a lot Juha for the work!

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings