Subject: RE: [mobile-ip] Thoughts on using handover capability extension

From: "Hemant Chaskar" <[email-masked]>
Date: Fri, 15 Nov 2002 21:08:51 +0000

Hi Raj:

I agree. There are various (in)feasibility issues in asking link types of 
other ARs from pAR -

1. How does pAR know geographical adjacency of interfaces? So, if I am 
connected to WAN pAR, and ask for availability of WLAN APs (or OWLAN APs for 
that matter) while moving around a busy area, WAN pAR will always say that 
there are many around. But if I never get indoor, I cannot use them, but my 
WLAN interface will be awake.

1a. Also, if I am going East and ask such question, I get availability info 
of OWLANs in all directions as WAN pAR may not know which direction I am 
moving.

In short, evidence of reachability is pre-requisite for handoff. And if MN 
can produce that evidence, it already knows link type.

2. Have we concluded that it is infeasible to do this wake-up business using 
physical layer techniques (a variation of how MNs wake up to check for pages 
in cellular case)? I think doing it at physical layer would be more accurate 
(IF wakes up when it detects signal/energy => evidence of reachability is 
automatic). So, only when I walk into the mall, WLAN IF wakes up, and not 
when I am walking in a garden near the mall. And if that is true, link type 
info may be superfluous.

Hemant

>From: [email-masked]
>To: <[email-masked]>, <[email-masked]>,        
><[email-masked]>
>Subject: RE: [mobile-ip] Thoughts on using handover capability extensio
>Date: Thu, 14 Nov 2002 16:41:03 -0600
>
> > > - it seems to me that folks prefer moving the PrRtSol
> > >    and PrRtAdv messages to an earlier time. Perhaps
> > >    we should recommend that the MN should send
> > >    PrRtSol after router discovery (RS/RA) or during router
> > >    discovery (see the next issue) ? In this message,
> > >    the MN sends a wildcard for target APs.
> >
> > The MN should also send some indication of the link
> > technology, for intertech handover, in addition.
> >
>
>Why? I am not sure if link technology knowledge is
>required for network layer HOs. Is this required in
>the PrRtAdv to awaken some idle interface at the MN?
>This would imply that the pAR knows what types of link
>technologies the MN can move to. Not feasible.
>
>-Basavaraj

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From: "James Kempf" <[email-masked]>
Date: Fri, 15 Nov 2002 15:25:09 -0800

If the MN asks for a mapping of all APs to ARs for link technology X that the
current AR knows about, and the current AR sends some, then the MN turn on its
card and check when it hears an AP. If the current AR sends none, then the MN
keeps the card off.

It does not need to be complicated.

How the current AR gets this information is out of scope for the AR to MN
protocol (though in scope potentially for a AR to AR protocol).

            jak