Most wireless link protocols that provide robust dormant mode support have a
separate dormant mode (aka paging) signaling channel that is extremely
narrowband and requires very low receiver power to monitor. This channel is
independent of the traffic channel over which IP traffic goes. Requiring the
terminal to wake up periodically, bring up the traffic channel for an RA,
then go to sleep again would result in considerably less power saving than
if the separate dormant mode channel is used. This is why your laptop can't
really do power efficient dormant mode on its 802.11 interfaces (802.11 has
no separate dormant mode signaling channel), while your cell phone regularly
gets something like 30 hours of dormant mode before the battery runs out
(cellular protocols do have such channels).
jak
----- Original Message -----
From: "Pars Mutaf" <[EMAIL PROTECTED]>
To: "Francis Dupont" <[EMAIL PROTECTED]>
Cc: <ipv6@ietf.org>
Sent: Tuesday, August 08, 2006 5:18 AM
Subject: Re: Proposal to change aspects of Neighbor Discovery
Hello,
On Tue, 2006-08-08 at 12:37 +0200, Francis Dupont wrote:
In your previous mail you wrote:
The I-D:
draft-madanapalli-ipv6-periodic-rtr-advts-00.txt
proposes several changes to ND procedures and parameters.
=> I strongly object not about the document itself but about its
principle because IMHO the link-layer should adapt, not the network
layer.
I agree with you of course. But I was thinking of this issue,
i.e. "how the link layer could adapt?"... It's not that easy.
Ideally, the dormant host's receiver circuit would be synchronized with
the router's periodic RAs. The receiver circuit would be switched ON
exactly when the RA arrives. But unfortunately, between the AR and the
host, there is an access point. The RA messages may be queued and
delayed at the access point (mixed up with other link layer frames).
This queuing delay may foil our dormant mode synchronization, and the
host may miss the RA messages :-(
This means that, perfect dormant mode synchronization can be more easily
achieved between the host and the access point (i.e. at the link layer).
In this case, however, the router's RAs will awaken the dormant host.
(unless the L2 access point recognizes the RA packets and forwards them
at the right time, i.e. when the host's receiver is ON).
Difficult issue.
Regards!
pars
Regards
[EMAIL PROTECTED]
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