[Dextrose] [Sugar-devel] Patch written for "Presence not updated, when client disconencts from telepathy-salut"

Tom Parker tom at carrott.org
Wed Jul 11 15:41:26 EDT 2012

(sending again reply all rather than reply-list)

On 11/07/12 02:58, Martin Langhoff wrote:
> A multicast "I'm here" would also do it, perhaps with less noise.
> Either way, we need to nag Salut devs on this.

I ran tcpdump (hint, it doesn't work on an XO unless you turn off 
promiscuous mode) a while ago and investigated the network traffic, my 
results should be in the auckland testing reports from a few months ago 
(certainly it was this year).

My recollection is that I found saw a broadcast or multicast packet from 
most or every node every minute or so and I'm fairly sure wireshark 
thought it was mdns related. My point is that I think there is already a 
heartbeat and you shouldn't need to send any more packets than are 
already sent to detect the exit of a laptop. I can't remember how this 
interacted with suspend-resume, if they were multicast, power saving 
shouldn't make a difference, if they were broadcast, power saving would 
cause significant disturbances, right?

We also found problems with nodes stopping listening to the multicast 
socket and the cluster becoming incoherent, but that may not be related 
to the current discussion.

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