On 12/02/14 10:12, Andrew Lunn wrote:
On Tue, Feb 11, 2014 at 01:48:15PM +0100, Antonio Quartulli wrote:
From: Antonio Quartulli antonio@open-mesh.com
In case of a unused link, the throughput estimation will get stuck to the last sampled value and therefore the reported metric will becomes obsolete.
Send unicast ELP packets to each neighbor to trigger throughput sampling on unused links.
Humm, i can understand the need for this, but i really think the rate control code should be sending the probes, not batman. What do the wifi people say about this? Have they tried submitting patches to them?
I am CC'ing Felix so that he can give his opinion. But last time I checked Minstrel I realised that it uses data packets to probe rates (there is not a specific probing packet), meaning that if there is no data packet to send, then no probing is performed.
Sending this ELP packets (when there is no unicast traffic) is a way to trigger this mechanism in Minstrel.
/* Instead of updating the metric each "received" ELP packet, it is * better to do it on each ELP sending. This way, if a node is dead and * does not send packets anymore, batman-adv is still able to timely * react to its death.
** The metric is updated by following these steps:* 1) if the hard_iface if wifi => send a unicast ELP for* probing/sampling to each neighbor* 2) update the metric value of each neighborMight be worth pointing out here, that because of queuing, there is no guarantee the ELP packets have been send yet and the RC estimated bandwidth could be up to 100ms old.
OK, I'll make it explicit. Actually this routine is no meant to get a "real time estimation", also because the routing algorithm would not be that fast to react on time.
Cheers,