Re: [Geopriv] [geopriv] #38: Section 1

From: Bernard Aboba ^lt;bernard_aboba@hotmail.com>
Date: Fri Aug 13 2010 - 13:31:15 EDT

Yes, what you say below makes a lot of sense. If a mobile host wants an updated
location, it has to obtain it somehow, regardless of the LCP it is using. In the case
of DHCP this need not necessarily entail obtaining a new address. Given that, is
the "applicability" text really unique to DHCP?

Also, I'd also like to see some statement made about wireless usage, if only to make
it clear that the mechanism is not purely for use in wired scenarios.

> Date: Fri, 13 Aug 2010 12:02:34 -0400
> Subject: Re: [Geopriv] [geopriv] #38: Section 1
> From: mlinsner@cisco.com
> To: bernard_aboba@hotmail.com; trac@tools.ietf.org
> CC: geopriv@ietf.org
>
> Bernard,
>
> A host using *any* LCP must initiate another message exchange to get updated
> location information when they determine it's necessary. This is the same
> whether the LCP is HELD, DHCP, LLDP-MED (or wait for 30 sec. for next
> packet), or .11(?). Hence, I don't understand your statement (in the
> context of this document), "where continuous triggering of DHCP might be
> most objectionable". Are not 'bits-on-the-wire', 'bits-on-the-wire'?
>
> My change to the current paragraph below stems from when I read the current
> text, one could infer that obtaining updated location information via the
> DHCP LCP mechanism is not possible. In fact, it is possible using a
> DHCPInform message (yes, renew of a lease also).
>
> Further, I believe it's fairly obvious that *only* using the DHCP RAIO
> options as a location determination mechanism renders device level location
> (more granular than just AP) *almost* impossible in an 802.11 network (since
> RAIO doesn't support measurements). So, when the connection AP is a DHCP
> relay agent, I don't believe there are any RAIO options that would allow the
> DHCP server to determine, by itself, device level location. Obviously
> someone could develop a connection between the DHCP server and the .11
> location determination infrastructure, but I don't think we should go there,
> nor even mention such in the document.
>
> Hence, I believe the most limiting factor to using DHCP as the LCI for
> wireless networks is the impracticality of the DHCP server performing device
> level location (vs. AP level location) determination using the available
> RAIO information. I also believe that we don't need to point this out as
> any developer will realize this within 30 seconds of thinking about.
>
> Does this make any sense?
>
> -Marc-
>
>
>
>
>
>
> On 8/13/10 10:46 AM, "Bernard Aboba" <bernard_aboba@hotmail.com> wrote:
>
> > My question with the paragraph is what it is trying to
> > convey about the "limited applicability".
> > We had discussed how DHCP might work reasonably well in
> > static or nomadic wireless scenarios, so that wireless
> > itself was not the issue.
> >
> > The original text seems to suggest that the issue is movement of
> > the mobile host without changing the point of attachment (which
> > will trigger a DHCP exchange).
> >
> > My presumption is that this is an issue in situations where
> > the location could change a great deal without a change to the point
> > of attachment. Unfortunately, it is these situations (e.g. wireless
> > WAN networks) where continuous triggering of DHCP might be
> > most objectionable.
> >
> >
> >
> > -----Original Message-----
> > From: Marc Linsner [mailto:mlinsner@cisco.com]
> > Sent: Friday, August 13, 2010 6:27 AM
> > To: geopriv issue tracker; bernard_aboba@hotmail.com
> > Cc: geopriv@ietf.org
> > Subject: Re: [Geopriv] [geopriv] #38: Section 1
> >
> > Bernard,
> >
> >
> > On 8/10/10 5:10 PM, "geopriv issue tracker" <trac@tools.ietf.org> wrote:
> >
> > In addition to the text that was removed, some text from
> >
> > draft-thomson-geopriv-3825bis was edited into Section 1:
> >
> > "The options defined in this document have limited applicability for
> >
> > mobile hosts. Typically DHCP clients refresh their configuration in
> >
> > response to changes in interface state or pending lease expirations. As a
> > result, when a mobile host changes location without subsequently
> >
> > completing another DHCP exchange, location configuration information
> >
> > initially obtained via DHCP could become outdated."
> >
> > [BA] By replacing the text on wireless usage with a statement of
> >
> > applicability relating to mobile uses, the overall impression that
> > Section
> > 1 leaves is a focus on wired uses.
> >
> >
> >
> > [ML] After re-reading the above text, I wonder if it might be better
> > understood to re-word:
> >
> > "The options defined in this document have limited applicability for
> >
> > mobile hosts. Typically DHCP clients refresh their configuration in
> >
> > response to changes in interface state or pending lease expirations. As a
> > result, when a mobile host changes location it MUST complete another DHCP
> > exchange to keep location current. Otherwise, the location configuration
> > information initially obtained via DHCP could become outdated."
> >
> > Comments?
> >
> > -Marc-
> >
> >
> >
>
>
                                               

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Received on Fri, 13 Aug 2010 10:31:15 -0700

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