[Olsr-users] Discrepancy between ETX value and ping packet loss
Wed Mar 18 18:25:16 CET 2015
Thanks for the confirmation. Would there be any disadvantage to just pushing the broadcast rate all the way to 11 (spinal tap style :))? Also, off the top of your head can you think of any other typical Mac or transport layer tuning that people do for high throughput TCP?
On 18 Mar 2015 05:28, Henning Rogge <(spam-protected)> wrote:
that is the reason... many mesh networks increase the basic multicast
rate to 6 MBit/s to ignore the old 802.11b rates.
On Tue, Mar 17, 2015 at 11:06 PM, Dan O'Keeffe <(spam-protected)> wrote:
> Hey again,
> Actually it's ok, I figured it out. Because the OLSR HELLO messages are
> broadcast at the 1Mbps data rate for 802.11, they experience a different
> packet loss to the 11Mbps unicast traffic.
> On 17/03/15 20:43, Dan O'Keeffe wrote:
>> I'm trying to use the OLSR ETX extensions to determine the path quality
>> to different destinations (so my application can send data to the
>> destination with the best path as the quality changes over time).
>> However the ETX values I'm seeing don't seem to correspond particularly
>> well to the packet loss I observe when I manually ping the different
>> More specifically, I have a two node network with each node running
>> olsrd and one node pinging the other (using a ping payload size of 0
>> so that the actual ping is just a 28 byte header). At a certain distance
>> the ping packet loss goes to 40%, but the ETX I observe using the
>> txtinfo plugin is 1.000 (i.e. from the output of 'echo "/all" | nc
>> localhost 2006).
>> Does anyone have an idea as to why I'm not seeing any packet loss
>> affecting the ETX? Using tshark I can see the OLSR control
>> messages being sent and received. However it's hard to tell whether
>> any of the control messages are actually being dropped, and so
>> I'm not sure whether the issue is that the OLSR control messages just
>> aren't experiencing packet loss or I haven't configured the ETX
>> calculation properly. From what I understand the ETX calculation should
>> be based on the number of hello messages sucessfully sent and received
>> over a sliding window, but perhaps there's more to the implementation?
>> The output of olsrd --version is:
>> *** olsr.org - 0.6.3-git_-hash_e334b612adcb7c22239a9dcafaf5b7ba - ***
>> Build date: 2013-03-28 03:47:37 on marid
>> I have made a few tweaks to the default config (see attached), but
>> I don't see that they should make a difference.
>> Finally, I should note that I'm running in an emulated environment
>> (using the CORE EMANE wireless network emulator). The only way I could
>> see that making a difference is that perhaps the same packet loss isn't
>> being applied to broadcast traffic as to normal traffic, but before I
>> check that on the CORE EMANE mailing list I'd just like to be sure there
>> isn't an obvious issue with my olsrd configuration.
>> Thanks for any help!
> Olsr-users mailing list
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Olsr-users