[Voyage-linux] Extreme asymmetry/poor throughput on link

[Edwin Whitelaw]

I'm running the latest Voyage on two ALIX boards on a 5.6km link.  One 
end has an SR5 and the other a Wistron CM11. There is a second CM11 on 
this unit that is disabled during the tests.  Both ends are co-located 
with several other systems, ie, there is considerable traffic on other 
5GHz channels at each location.  All the equipment is mine so I can 
monitor/change channels if needed.

The link in question is showing extreme asymmetry on iperf tests with as 
much as 40mbs going one way but rarely even 2mbs, and sometimes even 
<1mbs, the other way.

I've tried numerous channels, low and high band, as well as switching 
which end is master vs managed with no change in behavior. Some channels 
do seem to have better throughput in the "good" direction than others 
but I think that's fairly normal and the variation is relatively minor.

----iperf one way----
[  5] local 10.220.9.2 port 5001 connected with 10.220.9.1 port 2687
[  5]  0.0- 2.0 sec  6.54 MBytes  27.2 Mbits/sec
[  4] local 10.220.9.2 port 5001 connected with 10.220.9.1 port 2688
[  4]  0.0- 2.0 sec  4.79 MBytes  20.0 Mbits/sec
[  5] local 10.220.9.2 port 5001 connected with 10.220.9.1 port 2689
[  5]  0.0- 2.0 sec  7.56 MBytes  31.6 Mbits/sec
[  4] local 10.220.9.2 port 5001 connected with 10.220.9.1 port 2690
[  4]  0.0- 2.0 sec  7.95 MBytes  33.2 Mbits/sec
------------end-------------

------------iperf the other way-------
[  4]  0.0- 2.4 sec    632 KBytes  2.14 Mbits/sec
[  5] local 10.220.9.1 port 5001 connected with 10.220.9.2 port 1685
[  5]  0.0- 2.3 sec    328 KBytes  1.18 Mbits/sec
[  4] local 10.220.9.1 port 5001 connected with 10.220.9.2 port 1403
[  4]  0.0- 2.2 sec    224 KBytes    846 Kbits/sec
[  5] local 10.220.9.1 port 5001 connected with 10.220.9.2 port 1404
[  5]  0.0- 2.7 sec    184 KBytes    551 Kbits/sec
[  4] local 10.220.9.1 port 5001 connected with 10.220.9.2 port 1405
[  4]  0.0- 2.2 sec    144 KBytes    545 Kbits/sec
[  5] local 10.220.9.1 port 5001 connected with 10.220.9.2 port 1406
[  5]  0.0- 2.1 sec    568 KBytes  2.26 Mbits/sec
[  4] local 10.220.9.1 port 5001 connected with 10.220.9.2 port 1407
[  4]  0.0- 2.1 sec    456 KBytes  1.80 Mbits/sec
----end-----------

Has anyone experienced this and/or can someone suggest what aspect of 
the link might at fault? radios? ALIX board? settings? interference?

All the other systems at each site are performing normally, My own first 
guess is interference but I'd think that would be a case a mutual 
degradation and I'm not seeing that.

Any and all comments are welcome.

Thanks,

Edwin

-- 
<=+=+=+==+=+=+==+=+=+=+=+=+=+=+=>
Edwin Whitelaw, P.E.
New River Valley Unwired, LLC
2200 Lonesome Dove Dr
Christiansburg, VA 24073
540-239-0318