I have a laptop (let me call it A) with Intel Centrino 1030-N wireless (iwlwifi
module), running Arch Linux, and another laptop (I will call it B) with Atheros AR928X wireless (ath9k
module), running Ubuntu 11.10.
They connect to a wireless network provided by a D-Link DI-524 router (802.11g), which in turn connects to a DSL modem (10Mbps/1Mbps link)
Copying files between those machines, either through scp
or mounting a share via NFS or Samba, is very slow (at most 200 KB/s) and sometimes fails (times out), even when both machines are inches away from the router.
However, downloading files on either machine works correctly at the expected speeds (~1.2 MB/s).
I ran iperf
, as recommended in a comment, and it gave me this:
For the B
machine as server and the A
machine as client:
renan@B:~$ iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.0.125 port 5001 connected with 192.168.0.121 port 57153
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-11.1 sec 6.88 MBytes 5.19 Mbits/sec
renan@A:~$ iperf -c 192.168.0.125
------------------------------------------------------------
Client connecting to 192.168.0.125, TCP port 5001
TCP window size: 23.5 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.0.121 port 57153 connected with 192.168.0.125 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.8 sec 6.88 MBytes 5.32 Mbits/sec
For the A
machine as server and the B
machine as client:
renan@B:~$ iperf -c 192.168.0.121
------------------------------------------------------------
Client connecting to 192.168.0.121, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.0.125 port 34611 connected with 192.168.0.121 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.1 sec 8.38 MBytes 6.96 Mbits/sec
renan@A:~$ iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.0.121 port 5001 connected with 192.168.0.125 port 34611
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.8 sec 8.38 MBytes 6.51 Mbits/sec
The bandwidth is very low, as can be seen from those results.
Any clues?
scp sourcemachine:/some/where /tmp/xxx
)scp sourcemachine:file /tmp
gives slightly better results (I get peaks of 1 MB/s, but then it slows down).