Subject: RE: [seamoby] L2/L3 Paging

From: "Martin, David P" <[email-masked]>
Date: Wed, 28 Mar 2001 09:27:50 -0500

> Here's a puzzler though. Maybe it will help illuminate why us 
> L3 crazies
> keep raining on the paging-is-done-just-fine-at-L2 parade. Let's say I
> have a host with two radios, an 802.11 and a WCDMA. At some time it is
> reachable through both of them but is receiving IP traffic through the
> 802.11 radio. Then it goes to sleep. New traffic arrives for it. Which
> radio gets paged? Both? What if after going to sleep it wanders into a
> multipath null for the 802.11. What causes the WCDMA to 
> decide it needs
> to page the node and wake it up?

I agree that layer 3 paging is useful ... and I agree that layer 3 paging
would assist in the above scenario.  My concern is when layer 3 begins to
get involved in the assured delivery of packets between the edge router and
the end-point (AR-MN in this case).  In the example above, what if the MN
was in a deep fade for both technologies, do we buffer packets? for how
long?  What if the MN battery died or was removed for an extended period of
time (days)?  I realize these questions are in the solution space and we
have not yet entered the requirements phase.  But I am not clear if solving
these types of issues (assured delivery) would be part of the layer3 paging
protocol.  If we decide to take these issues on, I want it to be with eyes
wide open on the amount of work that will be required to address these
issues.  Otherwise, we can assume that the layer 2 interface(s) will handle
(or not) the delivery of the packet, and that the only thing we do with the
layer3 paging protocol is determine which interface(s) to deliver packets
to, which has substantial benefit in and of itself.

---

From: Michael Thomas <[email-masked]>
Date: Wed, 28 Mar 2001 09:51:51 -0800 (PST)

Martin, David P writes:
 > protocol.

David,

I hate to keep harping on this, but this sure
seems to me to be familar ground. The problems you
point out also would come up with a demand dialer
type of interface, like say an ISDN line which
isn't up all of the time. While the solutions may
not be entirely algorithmic, the parameters are
certainly well understood by now.

	Mike