[Voyage-linux] Reported RSSI different on AP vs client/throughput problem
Edwin Whitelaw
(spam-protected)
Mon Oct 2 22:03:08 HKT 2006
I have essentially identical WRAPs running Voyage 0.2. Unit A has an
SR5 (ath1) and CM9 (ath0), both in master mode. This system has three
client WRAPs, one a 5 mile (8000m) PtP link to Unit B and a PtMP link to
two other clients (C & D) connecting to Unit A's SR5, each with SR5s of
their own and a second Engenius as a local AP. The A-C and A-D
distances are 2.3 and 3.5 miles respectively
The PtMP link between A and C&D works fine with similarly reported RSSIs
on both Master and client end.
Iperf between hh1 (Unit B) and the master (Unit A) will vary between
<1mbs to well over 10mbs all while the signal strength remains fairly
constant. On occasion, the link will disappear long enough for ssh to
drop but will work again within just a few seconds.
Iperf between A and either C or D is excellent with values typically
just under 20mbs.
Unit B has a CM9 (ath1) and an Engenius NL2511MP Plus (wlan0). The
client consistently reports excellent signal strengths:
hh1:~# iwconfig ath1
ath1 IEEE 802.11a ESSID:"buffalo-hh"
Mode:Managed Frequency:5.765 GHz Access Point: 00:0B:6B:36:FE:21
Bit Rate:24 Mb/s Tx-Power=16 dBm Sensitivity=0/3
Retry:off RTS thr:off Fragment thr:off
Encryption key:<key obscured> Security mode:restricted
Power Management:off
Link Quality=39/94 Signal level=-56 dBm Noise level=-95 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
Note that the tx power is 16db. Setting to 17 works for a while but
then reverts to 16 after a short time. RSSI values on the master don't
obviously reflect the 1 db change in any case.
While the master shows:
buffalo-fnb-hh:~# iwconfig ath0
ath0 IEEE 802.11a ESSID:"buffalo-hh"
Mode:Master Frequency:5.765 GHz Access Point: 00:0B:6B:36:FE:21
Bit Rate:0 kb/s Tx-Power:17 dBm Sensitivity=0/3
Retry:off RTS thr:off Fragment thr:off
Encryption key:<key obscured> Security mode:restricted
Power Management:off
Link Quality=21/94 Signal level=-74 dBm Noise level=-95 dBm
Rx invalid nwid:1 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
I have an almost identical arrangement in another part of my network,
one WRAP with the same two cards feeding two downstream units at similar
distances and have no problems.
I at first thought that the antenna and diversity settings were the
problem but they are the same as int he other system. The antenna lead
is connected to the primary port on the CM9s.
hh1:~# cat /proc/sys/dev/wifi1/diversity
1
hh1:~# cat /proc/sys/dev/wifi1/txantenna
0
hh1:~# cat /proc/sys/dev/wifi1/rxantenna
1
(Just tried disabling diversity both ends of the PtP link. No change in
behavior)
In a PtP link, why do the master and client show such widely differing
RSSIs? In a PtMP link, does the master show the stronger(est) of the
client signals?
I have tried any number of channels on the A-B link, including both the
lower and upper bands. Good RSSI reported on the client end but the
throughput and flakiness issues remain. My next attempt at fixing will
be to replace the CM9s with SR5s though have avoided so far since that
involves two water tank climbs. :-(
dmesg output from client hh1 (Unit B):
hostap_pci: 0.4.4-kernel (Jouni Malinen <jkmaline at cc.hut.fi>)
hostap_pci: Registered netdevice wifi0
wifi0: Original COR value: 0x21
prism2_hw_init: initialized in 196 ms
wifi0: NIC: id=0x8013 v1.0.0
wifi0: PRI: id=0x15 v1.1.1
wifi0: STA: id=0x1f v1.8.2
wifi0: Intersil Prism2.5 PCI: mem=0xa0000000, irq=9
wifi0: registered netdevice wlan0
SC1x00 Watchdog driver by Inprimis Technolgies.
wd1100.c: a few hacks by erich.titl at think.ch
Last reboot was by watchdog!
ath_hal: module license 'Proprietary' taints kernel.
ath_hal: 0.9.16.16 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413)
wlan: 0.8.4.2 (svn 1527)
ath_rate_sample: 1.2 (svn 1527)
ath_pci: 0.9.4.5 (svn 1527)
wifi1: 11a rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
wifi1: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
wifi1: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps
24Mbps 36Mbps 48Mbps 54
Mbps
wifi1: turboA rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
wifi1: turboG rates: 6Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
wifi1: H/W encryption support: WEP AES AES_CCM TKIP
wifi1: mac 5.9 phy 4.3 radio 3.6
wifi1: Use hw queue 1 for WME_AC_BE traffic
wifi1: Use hw queue 0 for WME_AC_BK traffic
wifi1: Use hw queue 2 for WME_AC_VI traffic
wifi1: Use hw queue 3 for WME_AC_VO traffic
wifi1: Use hw queue 8 for CAB traffic
wifi1: Use hw queue 9 for beacons
wifi1: Atheros 5212: mem=0x80000000, irq=12
dmesg from master buffalo-fnb-hh Unit A):
ath_hal: 0.9.16.16 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413)
wlan: 0.8.4.2 (svn 1527)
ath_rate_sample: 1.2 (svn 1527)
ath_pci: 0.9.4.5 (svn 1527)
wifi0: 11a rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
wifi0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
wifi0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps
24Mbps 36
Mbps 48Mbps 54Mbps
wifi0: turboA rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
wifi0: turboG rates: 6Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
wifi0: H/W encryption support: WEP AES AES_CCM TKIP
wifi0: mac 5.9 phy 4.3 radio 3.6
wifi0: Use hw queue 1 for WME_AC_BE traffic
wifi0: Use hw queue 0 for WME_AC_BK traffic
wifi0: Use hw queue 2 for WME_AC_VI traffic
wifi0: Use hw queue 3 for WME_AC_VO traffic
wifi0: Use hw queue 8 for CAB traffic
wifi0: Use hw queue 9 for beacons
wifi0: Atheros 5212: mem=0x80000000, irq=12
wifi1: 11a rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
wifi1: turboA rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
wifi1: H/W encryption support: WEP AES AES_CCM TKIP
wifi1: mac 5.9 phy 4.3 radio 3.6
wifi1: Use hw queue 1 for WME_AC_BE traffic
wifi1: Use hw queue 0 for WME_AC_BK traffic
wifi1: Use hw queue 2 for WME_AC_VI traffic
wifi1: Use hw queue 3 for WME_AC_VO traffic
wifi1: Use hw queue 8 for CAB traffic
wifi1: Use hw queue 9 for beacons
wifi1: Atheros 5212: mem=0x80080000, irq=9
--
<=+=+=+==+=+=+==+=+=+=+=+=+=+=+=>
Edwin Whitelaw, P.E.
New River Valley Unwired, LLC
2200 Lonesome Dove Dr
Christiansburg, VA 24073
540-239-0318
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