Re: [16NG] Resolutions to issues raised during 2nd WGLC of I-D draft-ietf-16ng-ipv6-over-ipv6cs-04 [1]

Hi Alex,

On 1/12/07 5:06 AM, "ext Alexandru Petrescu"
<alexandru.petrescu@motorola.com> wrote:

> 
> Periodic RA is in widespread use for movement detection.  I do not
> understand the opposition to use periodic RAs as allowed by rfc3775.
> What breaks if we use periodic RAs with a frequency higher than 1/4s?
> (remark arguments of air interface gains are different on high-bandwidth
> links).

The fact is that sending periodic RAs on an air interface irrespective of BW
capacity is suboptimal.
A host in Idle mode is not listening for periodic RAs. Listening for
periodic RAs would prevent the host from transitioning to idle mode which
has an adverse impact on battery life. 802.16 has defined paging and Idle
mode support. In air-interfaces that do not support such capability, sending
of very frequent RAs is possible but IMO still not the most efficient usage
of the bandwidth. 
In licensed spectrum the optimization and efficiency of the air interface is
critical. Periodic RAs are unavoidable at this time. The best that we can do
without breaking backward compatibility is to send it with large time
intervals as the I-D suggests.
Movement detection can be done be accomplished by other means. If the host
is only relying on RAs for movement detection (at the IP layer), then it
could just as well send a Rtr solicitation. This is not prevented.

In Unlicensed spectrum you may have a bit more liberty about how the
air-interface is used but even in those cases, optimizing it is a better
choice.

-Raj

> 
> Alex

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