Subject: RE: [seamoby] WG Last Call: I-D ACTION:draft-seamoby-paging-probl em-statement-00.txt (Fwd)

From: "Hesham Soliman (ERA)" <[email-masked]>
Date: Fri, 9 Feb 2001 21:50:25 +0100

Hello, 

I have some initial comments on the draft and will follow that later
with some more detailed ones. 
So here they are:

General comment: The assumption that L3 packets can only
be sent on certain channels is not correct. The whole draft
seems to be based on that assumption. I disagree with that
unless one of the team members can explain it better to me. 
I'm sure this would have been discussed in detail. 

"Dormant Mode -  A state in which a mobile can not receive IP
      packets, but may still be able to receive L2 signalling related to
      tracking the mobile's location. A mobile may transition out of
      dormant mode due to a lower layer interface message (possibly
      triggered by receipt of an IP packet) or a timer expiration. A
      dormant terminal may signal to the network when it changes paging
      area, but may delay the signal until the next time it wakes up
      (if, for example, the mobile is using a time-slotted dormant mode
      algorithm). Note that a terminal which is continuously listening
      to L2 for receipt of L3 packets is not in dormant mode. "

=> This definition of dormant mode is not correct. A dormant mobile
is a mobile that can only receive information on certain channels 
and not others. This has absolutely nothing to do with the nature
of this information or which layer it is adressing (L2 or L3). 
For example in the cellular networks I'm half familiar with, a dormant
mobile can receive/send signalling messages on common channels. 
A dormant mobile is a mobile that does not have a traffic channel 
setup. Therfore saying that it can not receive L3 packets is not 
true. Maybe in today's cellular networks the system designers 
chose to send L3 signalling on traffic channels. But of course 
that should NOT imply that this is the definition of dormancy. 
After all there is no L3 paging in today's cellular networks. 

In chapter 3:

"An L3 paging protocol is sensible only if L2 supports paging. In the
   absence of L2 paging, L3 paging achieves no reduction in power drain
   because the mobile is forced to monitor L2 for L3 paging messages."

=> I dont see how this can be right ? This is a statement that simply
removes the need of L3 paging altogether. If you need L2 paging
then what's L3 paging needed for ??

   "Having the mobile constantly listen to L2 for L3 packets is NOT
   considered to be adequate L2 support, because it does not achieve
   enough power savings to be meaningful. "

=> The mobile has to listen to L2 all the time. Again there is
an underlying assumption here that L3 packets are only sent 
on certain bearers. That's a bad assuption IMO. If someone disagrees
with that then please explain why this is the case. I don't think 
that sending L3 packets on other channels breaks any laws of 
physics. Or maybe I missed something ?

The references to both V4 and V6 drafts are incorrect. There is 
a new V6 draft that is completely different and is now the WG
draft in the MIP WG. We've been discussing it for a while now on 
this list so please refer to it.
Also there is a new V4 draft that will also be the WG draft. 
I guess I shouldn't need to remind the editor ;)

Regards,
Hesham

---

From: Ram Ramjee <[email-masked]>
Date: Sun, 11 Feb 2001 20:16:45 -0500

Hesham,

We had a discussion on L3 paging vs L2 paging over the air. My
understanding of the conclusion on that topic was that we would
limit our scope to existing wireless networks (where doing L3 paging without
physical/link layer support on the air-interface could result in power
consumption inefficienies at the mobile
host)...a few people did remark that signaling overhead could
still be reduced in such a case, but, that was deemed to be
of lesser importance.

Note that L3 paging may still be needed in the network, for eg.-,
the case where multiple paging areas map onto one subnet.

Cheers,
Ram