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We are using the following 1Gbit/s radio link setup: Location A:

  • internet gateway with 1Gbits/s sym. fiber
  • most of our servers including dhcp, dns, fileservers (smb), voip-server, exchange-server
  • 55 clients/users
  • directional radio relay A (Lightpointe AireLink 60 SX) - 1Gbits/s

Location B:

  • one fileserver (smb)
  • 30 clients/users
  • directional radio relay B (Lightpointe AireLink 60 SX) - 1Gbits/s

Distance between locations A and B is 177 meters. Both locations are sharing one subnet: 192.168.0.0/24 for clients and servers, VoIP phones are in subnet 10.6.3.0/24 (shared with both locations as well). So there is no routing between both locations and the radio link is working as a bridge.

Settings of the directional radio relay A:

Link Status: UP
Mode: Data
RSSI, dBm: -46
RSSI Alarm Thrshld, dBm: -60
RSSI Alarm Clear, dBm: -50
RF Link: high    
TX RF Band, GHz: 62.5
RX RF Band, GHz: 59.5
TX Power, dBm: -7
Distance: Very short
ACM: Enabled
Modulation: 16QAM 5/8
TX Lock: normal lock
RX Lock: normal lock
Modem Lock: locked

Settings of the directional radio relay B:

Link Status: UP
Mode: Data
RSSI, dBm: -49
RSSI Alarm Thrshld, dBm: -60
RSSI Alarm Clear, dBm: -50
RF Link: low
TX RF Band, GHz: 59.5
RX RF Band, GHz: 62.5
TX Power, dBm: -4
Distance: Very short
ACM: Enabled
Modulation: 16QAM 5/8
TX Lock: normal lock
RX Lock: normal lock
Modem Lock: locked

RF Link RX Error directional radio relay A: 0 RF Link RX Error directional radio relay B: 0

We are experiencing the following problems at location B:

  • VoIP audio interrupts (mostly only one direction a time for about 3 seconds each)
  • smb throughput sometimes drops to 5 Mbit/s or even lower
  • outgoing mail (exchange server) is very slow sometimes
  • slow Internet connection

File transfer rate drops to zero and file transfer aborts with 0x8007003B (location A->B): sample 1: file transfer rate drops to zero and file transfer aborts sample 2: file transfer rate drops to zero and file transfer aborts

to sum it up: it seems as there is something causing a massive throughput drop, but we don't know what is happening here. We installed two "man-in-the-middle" servers with two bridged Ethernet ports each to collect some data with ntopng and tshark at both locations between the radio link data port and the switch port connecting it to the local network.

There are no problems accessing servers of location A from client of location A and accessing servers of location B from clients of location B.

  • server.location-a = 192.168.0.149
  • server.location-b = 192.168.0.242

iperf is showing good data rates:

user@location-a:~$ iperf -c server.location-b -i 2 -t 20
------------------------------------------------------------
Client connecting to server.location-b, TCP port 5001
TCP window size:  512 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.149 port 63378 connected with 192.168.0.242 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 2.0 sec   198 MBytes   832 Mbits/sec
[  3]  2.0- 4.0 sec   195 MBytes   817 Mbits/sec
[  3]  4.0- 6.0 sec   198 MBytes   831 Mbits/sec
[  3]  6.0- 8.0 sec   199 MBytes   836 Mbits/sec
[  3]  8.0-10.0 sec   165 MBytes   692 Mbits/sec
[  3] 10.0-12.0 sec   198 MBytes   829 Mbits/sec
[  3] 12.0-14.0 sec   195 MBytes   817 Mbits/sec
[  3] 14.0-16.0 sec   193 MBytes   810 Mbits/sec
[  3] 16.0-18.0 sec   200 MBytes   838 Mbits/sec
[  3] 18.0-20.0 sec   199 MBytes   833 Mbits/sec
[  3]  0.0-20.0 sec  1.89 GBytes   814 Mbits/sec

both directions with --tradeoff (-r)

user@location-a:~$ iperf -c server.location-b -i 2 -t 20 -r
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 1.00 MByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to server.location-b, TCP port 5001
TCP window size:  512 KByte (default)
------------------------------------------------------------
[  4] local 192.168.0.149 port 49535 connected with 192.168.0.242 port 5001
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0- 2.0 sec   191 MBytes   801 Mbits/sec
[  4]  2.0- 4.0 sec   196 MBytes   824 Mbits/sec
[  4]  4.0- 6.0 sec   196 MBytes   822 Mbits/sec
[  4]  6.0- 8.0 sec   193 MBytes   809 Mbits/sec
[  4]  8.0-10.0 sec   196 MBytes   821 Mbits/sec
[  4] 10.0-12.0 sec   187 MBytes   783 Mbits/sec
[  4] 12.0-14.0 sec   164 MBytes   690 Mbits/sec
[  4] 14.0-16.0 sec   166 MBytes   697 Mbits/sec
[  4] 16.0-18.0 sec   191 MBytes   803 Mbits/sec
[  4] 18.0-20.0 sec   196 MBytes   820 Mbits/sec
[  4]  0.0-20.0 sec  1.83 GBytes   787 Mbits/sec
[  4] local 192.168.0.149 port 5001 connected with 192.168.0.242 port 45775
[  4]  0.0- 2.0 sec   221 MBytes   928 Mbits/sec
[  4]  2.0- 4.0 sec   221 MBytes   929 Mbits/sec
[  4]  4.0- 6.0 sec   222 MBytes   933 Mbits/sec
[  4]  6.0- 8.0 sec   222 MBytes   933 Mbits/sec
[  4]  8.0-10.0 sec   222 MBytes   932 Mbits/sec
[  4] 10.0-12.0 sec   188 MBytes   789 Mbits/sec
[  4] 12.0-14.0 sec   223 MBytes   935 Mbits/sec
[  4] 14.0-16.0 sec   222 MBytes   932 Mbits/sec
[  4] 16.0-18.0 sec   223 MBytes   934 Mbits/sec
[  4] 18.0-20.0 sec   222 MBytes   933 Mbits/sec
[  4]  0.0-20.0 sec  2.14 GBytes   918 Mbits/sec

reversing iperf server and client:

user@location-b:~# iperf -c server.location-a -i 2 -t 20
------------------------------------------------------------
Client connecting to server.location-a, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.242 port 45778 connected with 192.168.0.149 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 2.0 sec   220 MBytes   921 Mbits/sec
[  3]  2.0- 4.0 sec   218 MBytes   916 Mbits/sec
[  3]  4.0- 6.0 sec   217 MBytes   910 Mbits/sec
[  3]  6.0- 8.0 sec   221 MBytes   926 Mbits/sec
[  3]  8.0-10.0 sec   213 MBytes   892 Mbits/sec
[  3] 10.0-12.0 sec   188 MBytes   787 Mbits/sec
[  3] 12.0-14.0 sec   218 MBytes   916 Mbits/sec
[  3] 14.0-16.0 sec   218 MBytes   916 Mbits/sec
[  3] 16.0-18.0 sec   219 MBytes   919 Mbits/sec
[  3] 18.0-20.0 sec   223 MBytes   937 Mbits/sec
[  3]  0.0-20.0 sec  2.10 GBytes   904 Mbits/sec

dualtest with -d:

user@location-b:~# iperf -c server.location-a -i 2 -t 10 -d
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to server.location-a, TCP port 5001
TCP window size:  255 KByte (default)
------------------------------------------------------------
[  5] local 192.168.0.242 port 45784 connected with 192.168.0.149 port 5001
[  4] local 192.168.0.242 port 5001 connected with 192.168.0.149 port 52423
[ ID] Interval       Transfer     Bandwidth
[  5]  0.0- 2.0 sec   210 MBytes   882 Mbits/sec
[  4]  0.0- 2.0 sec  45.7 MBytes   192 Mbits/sec
[  5]  2.0- 4.0 sec   172 MBytes   722 Mbits/sec
[  4]  2.0- 4.0 sec  50.8 MBytes   213 Mbits/sec
[  5]  4.0- 6.0 sec   205 MBytes   859 Mbits/sec
[  4]  4.0- 6.0 sec  65.5 MBytes   275 Mbits/sec
[  5]  6.0- 8.0 sec   215 MBytes   901 Mbits/sec
[  4]  6.0- 8.0 sec  73.0 MBytes   306 Mbits/sec
[  5]  8.0-10.0 sec   223 MBytes   934 Mbits/sec
[  5]  0.0-10.0 sec  1.00 GBytes   860 Mbits/sec
[  4]  8.0-10.0 sec  55.0 MBytes   231 Mbits/sec
[  4]  0.0-10.0 sec   290 MBytes   243 Mbits/sec

iperf both directions while starting a smb file transfer location A -> B (there is no problem starting a smb filetransfer from location B -> A:

user@location-b:~# iperf -c server.location-a -i 1 -t 30 -r
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to server.location-a, TCP port 5001
TCP window size:  238 KByte (default)
------------------------------------------------------------
[  5] local 192.168.0.242 port 45787 connected with 192.168.0.149 port 5001
[ ID] Interval       Transfer     Bandwidth
[  5]  0.0- 1.0 sec   111 MBytes   934 Mbits/sec
[  5]  1.0- 2.0 sec   109 MBytes   913 Mbits/sec
[  5]  2.0- 3.0 sec   111 MBytes   928 Mbits/sec
[  5]  3.0- 4.0 sec   111 MBytes   932 Mbits/sec
[  5]  4.0- 5.0 sec   111 MBytes   928 Mbits/sec
[  5]  5.0- 6.0 sec   101 MBytes   844 Mbits/sec
[  5]  6.0- 7.0 sec  73.8 MBytes   619 Mbits/sec
[  5]  7.0- 8.0 sec   111 MBytes   929 Mbits/sec
[  5]  8.0- 9.0 sec   109 MBytes   916 Mbits/sec
[  5]  9.0-10.0 sec   112 MBytes   938 Mbits/sec
[  5] 10.0-11.0 sec   109 MBytes   918 Mbits/sec
[  5] 11.0-12.0 sec   111 MBytes   933 Mbits/sec
[  5] 12.0-13.0 sec   106 MBytes   891 Mbits/sec
[  5] 13.0-14.0 sec  85.8 MBytes   719 Mbits/sec
[  5] 14.0-15.0 sec   112 MBytes   935 Mbits/sec
[  5] 15.0-16.0 sec   111 MBytes   934 Mbits/sec
[  5] 16.0-17.0 sec   110 MBytes   924 Mbits/sec
[  5] 17.0-18.0 sec   112 MBytes   937 Mbits/sec
[  5] 18.0-19.0 sec   112 MBytes   940 Mbits/sec
[  5] 19.0-20.0 sec   112 MBytes   935 Mbits/sec
[  5] 20.0-21.0 sec   111 MBytes   928 Mbits/sec
[  5] 21.0-22.0 sec   110 MBytes   923 Mbits/sec
[  5] 22.0-23.0 sec  79.1 MBytes   664 Mbits/sec
[  5] 23.0-24.0 sec   112 MBytes   937 Mbits/sec
[  5] 24.0-25.0 sec   112 MBytes   936 Mbits/sec
[  5] 25.0-26.0 sec   111 MBytes   934 Mbits/sec
[  5] 26.0-27.0 sec   112 MBytes   937 Mbits/sec
[  5] 27.0-28.0 sec   111 MBytes   928 Mbits/sec
[  5] 28.0-29.0 sec   112 MBytes   938 Mbits/sec
[  5] 29.0-30.0 sec   112 MBytes   941 Mbits/sec
[  5]  0.0-30.0 sec  3.15 GBytes   901 Mbits/sec
[  4] local 192.168.0.242 port 5001 connected with 192.168.0.149 port 52898
[  4]  0.0- 1.0 sec   104 MBytes   872 Mbits/sec
[  4]  1.0- 2.0 sec   103 MBytes   867 Mbits/sec
[  4]  2.0- 3.0 sec  97.9 MBytes   822 Mbits/sec
[  4]  3.0- 4.0 sec  95.9 MBytes   804 Mbits/sec
[  4]  4.0- 5.0 sec   101 MBytes   851 Mbits/sec
[  4]  5.0- 6.0 sec   102 MBytes   860 Mbits/sec
[  4]  6.0- 7.0 sec   103 MBytes   867 Mbits/sec
[  4]  7.0- 8.0 sec   103 MBytes   868 Mbits/sec
[  4]  8.0- 9.0 sec  50.0 MBytes   419 Mbits/sec
[  4]  9.0-10.0 sec  14.8 MBytes   124 Mbits/sec
[  4] 10.0-11.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 11.0-12.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 12.0-13.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 13.0-14.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 14.0-15.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 15.0-16.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 16.0-17.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 17.0-18.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 18.0-19.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 19.0-20.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 20.0-21.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 21.0-22.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 22.0-23.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 23.0-24.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 24.0-25.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 25.0-26.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 26.0-27.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 27.0-28.0 sec  0.00 Bytes  0.00 bits/sec
[  4]  0.0-28.9 sec   876 MBytes   255 Mbits/sec
Alex
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Stephan
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    You have quite a bit of data detaling that this issue does happen, but nothing that would reveal why it happens. Have you collected traffic dumps from these wireless interfaces while the problem is presenting itself? Any anomolies there would be potentially helpful. I'm also not seeing any data directly from the APs themselves during these almost-outages. That would help to determine if there is some kind of signal fade between the two. Maybe a paper factory is releasing scheduled fart gas. – Spooler Mar 09 '18 at 13:09
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    Are there any physical obstacles between antennas? Pigeons? – Nikolai Apr 09 '18 at 09:09
  • And to add to the "physical influences": Any chance the antennas can swing out of the required direction by wind, vibration etc.? Any other senders on this frequency that may be on from time to time, and cause interference? It might be worth recording the times when your throughput drops, and correlating it with possible influences. – dirkt Jan 04 '19 at 07:13

1 Answers1

1

multi-path reflections ? try to offset the pair by a little degrees, I dont know which kind of modulation is used but i imagine that in FHSS style you can have a lot of trouble without warning from the hardware

Vincent Bellazzi
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