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chvdr
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18km link CM9 ws SR5, 40Mbit, but some packet loss.

Tue Sep 19, 2006 12:27 pm

hi there,

i have a simple problem with a link, such as follows:
link works usually fine, but with some ping timeouts. several packets loss (once per 15-20 minutes and rearly ping loses sequence of several packets) and 1ms at the rest of the time. at hte same time link transfers 4-5Mbps of traffic. both sites does not contain connect/dosconnect messages in the log.

there is a link. 18km, MT boxes both sites. CM9 and SR5, 2.6GHz, 1.20m dishes with 1m low loss cable both sites, 2.9.11(not upgradeble yet). 5GHz-turbo, nstreme enabled. 36Mbits modulation limited. bandwith test shows 40Mbps at TCP, random data=no.

is there a known reason to loss packets.

regards,
C. G.
 
sten
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Tue Sep 19, 2006 6:24 pm

something else on the same/neighboring frequencies?
Move along. Nothing to see here.
 
jo2jo
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Wed Sep 20, 2006 12:42 am

whats noise floor read on both radios?
 
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chvdr
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Wed Sep 20, 2006 5:24 am

something else on the same/neighboring frequencies?
channel is 5210. sr5 @ 5,8GHz is near but i think it's not a problem.
 
UniKyrn
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Wed Sep 20, 2006 7:13 am

You're pushing a link 18KM, getting a packet dropped every 15-20 minutes and you think you've got a problem? I suspect most WISP's pray to have as few problems as that. :)

You get packet losses even on hardwire, don't be surprised when an 18KM RF link looses packets also. That's why TCP had retries. :)
 
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chvdr
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Wed Sep 20, 2006 12:50 pm

You're pushing a link 18KM, getting a packet dropped every 15-20 minutes and you think you've got a problem? I suspect most WISP's pray to have as few problems as that. :)

You get packet losses even on hardwire, don't be surprised when an 18KM RF link looses packets also. That's why TCP had retries. :)
serious? in most our links there is packet loss approx. equal to 0. and if loosed, there is a single packet, not a sequence of packets.
here i talking about sequences of 5-6 loosed packets.

do you really mean that's normal?

regards,
C. G.
 
UniKyrn
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Wed Sep 20, 2006 8:55 pm

Yes, I'm serious, loosing an occasional packet is normal, these aren't perfect systems.
 
jarosoup
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Wed Sep 20, 2006 10:38 pm

One packet dropped every 15 minutes is nothing to worry about. Are you using periodic calibration on the radios?
 
sten
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Thu Sep 21, 2006 4:17 am

you mention 5ghz-turbo and 36 mbit modulation.
what's your signal strength and signal to noise ratio?
do you run nstreme?

anything between 0% and 0.01% packet loss at 50% bandwidth is normal.
Loss up to 1% is normal when bandwidth usage is at around 90% (all depending on how you configure it of course)
most packetloss is caused by cables but probably not in your situation?
Move along. Nothing to see here.
 
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chvdr
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Thu Sep 21, 2006 11:32 am

@sten: signal is usually -68/70dBm. Nstreme enabled. Export of "/interface wireless " listed bellow:

/ interface wireless
set wlan1 name="wlan1" mtu=1500 mac-address=00:15:6D:51:02:99 arp=enabled \
disable-running-check=no radio-name="ZZZ-1" mode=station \
ssid="ZZZZZ" area="" frequency-mode=superchannel country=no_country_set \
antenna-gain=0 frequency=5250 band=5ghz-turbo scan-list=default \
rate-set=configured \
supported-rates-a/g=6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps \
basic-rates-a/g=6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps \
max-station-count=2007 ack-timeout=dynamic tx-power-mode=default \
noise-floor-threshold=default periodic-calibration=default \
burst-time=disabled dfs-mode=none antenna-mode=ant-a wds-mode=disabled \
wds-default-bridge=none wds-ignore-ssid=no update-stats-interval=disabled \
default-authentication=yes default-forwarding=yes default-ap-tx-limit=0 \
default-client-tx-limit=0 hide-ssid=no security-profile=default \
disconnect-timeout=3s on-fail-retry-time=100ms preamble-mode=both \
compression=no allow-sharedkey=no comment="" disabled=no
/ interface wireless nstreme
set wlan1 enable-nstreme=yes enable-polling=yes framer-policy=none \
framer-limit=3200
/ interface wireless manual-tx-power-table
set wlan1 manual-tx-powers=1Mbps:17,2Mbps:17,5.5Mbps:17,11Mbps:17,6Mbps:17,9Mbps:\
17,12Mbps:17,18Mbps:17,24Mbps:17,36Mbps:17,48Mbps:17,54Mbps:17
/ interface wireless security-profiles



regards,
C. G.
 
sten
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Thu Sep 21, 2006 6:05 pm

That can be improved a little bit. What configuration is used on the ap-bridge side?

Calibration should be enabled, and anything that is dynamic should be made static.
Move along. Nothing to see here.
 
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chvdr
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Thu Sep 21, 2006 8:13 pm

what shuld it mean "anything that is dynamic should be made static"?

regards,
C. G.
Calibration should be enabled, and anything that is dynamic should be made static.
 
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chvdr
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Thu Sep 21, 2006 8:16 pm

@sten: ap's configuration listed bellow:

==========================
[admin@18999] > /interface wireless
[admin@18999] interface wireless> ex
# sep/21/2006 20:03:22 by RouterOS 2.9.11
# software id = DUV0-6Y0
#
/ interface wireless



set wlan1 name="wlan1" mtu=1500 mac-address=00:0B:6B:33:CB:7A arp=enabled \
disable-running-check=no radio-name="000B6B33CB7A" mode=bridge ssid="ZZZZZ" \
area="" frequency-mode=manual-txpower country=no_country_set antenna-gain=0 \
frequency=5290 band=5ghz-turbo scan-list=default rate-set=configured \
supported-rates-b=1Mbps,2Mbps,5.5Mbps,11Mbps \
supported-rates-a/g=6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps basic-rates-b=1Mbps \
basic-rates-a/g=6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps max-station-count=2007 \
ack-timeout=dynamic tx-power-mode=default noise-floor-threshold=default \
periodic-calibration=default burst-time=disabled dfs-mode=none antenna-mode=ant-a \
wds-mode=disabled wds-default-bridge=none wds-ignore-ssid=no \
update-stats-interval=disabled default-authentication=yes default-forwarding=yes \
default-ap-tx-limit=0 default-client-tx-limit=0 hide-ssid=no security-profile=default \
disconnect-timeout=3s on-fail-retry-time=100ms preamble-mode=both comment="" \
disabled=no

/ interface wireless nstreme
set wlan1 manual-tx-powers=1Mbps:17,2Mbps:17,5.5Mbps:17,11Mbps:17,6Mbps:17,9Mbps:17,12Mbps\
:17,18Mbps:17,24Mbps:17,36Mbps:17,48Mbps:17,54Mbps:17
[admin@18999] interface wireless>
============================

kind regards,
C. G.
 
tully
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Fri Sep 22, 2006 8:35 am

basic-rates a/g should be left to the default of 6Mb/s (unless you are experimenting). Most likely you should set all to default and start over and config only the basics.
 
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chvdr
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Fri Sep 22, 2006 9:28 am

i cannot set everything to default, because it's an important router with several interfaces, routing 400 single users and more, eoip and vpn tunnels etc.
basic-rates a/g should be left to the default of 6Mb/s (unless you are experimenting). Most likely you should set all to default and start over and config only the basics.
now basic rates are set to default.
there no a result, because the problem is sporadic.

regards,
C. G.
 
aviper
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Fri Sep 22, 2006 10:20 am

Then get dedicated machine for the wireless link.
MT is good router
MT is good AP
MT is good CPE
But things get worst, when you use it for everything !

?
/system resources print
?
/system resources irq print
 
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chvdr
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Fri Sep 22, 2006 2:50 pm

...
...
...?
/system resources print
?
/system resources irq print

[admin@1899999] > /system resource pr
uptime: 2d4h59m16s
free-memory: 213712kB
total-memory: 256728kB
cpu: "Intel(R)"
cpu-frequency: 2663MHz
cpu-load: 20
free-hdd-space: 86308kB
total-hdd-space: 121215kB
write-sect-since-reboot: 1240
write-sect-total: 120664
[admin@1899999] > /system resource pci pr
# DEVICE VENDOR NAME IRQ
0 02:01.0 Atheros Communications, Inc. AR5212 802.11abg NIC (rev: 1) 11
1 02:02.0 Atheros Communications, Inc. AR5212 802.11abg NIC (rev: 1) 11
2 02:03.0 Atheros Communications, Inc. AR5212 802.11abg NIC (rev: 1) 5
3 02:00.0 Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev: 16) 5
4 02:05.0 Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev: 16) 11
5 01:00.0 nVidia Corporation NV18 [GeForce4 MX 440 AGP 8x] ... 10
6 00:1f.5 Intel Corporation 82801EB/ER (ICH5/ICH5R) AC'97 ... 5
7 00:1f.3 Intel Corporation 82801EB/ER (ICH5/ICH5R) SMBus ... 5
8 00:1f.1 Intel Corporation 82801EB/ER (ICH5/ICH5R) IDE Co... 0
9 00:1f.0 Intel Corporation 82801EB/ER (ICH5/ICH5R) LPC In... 0
10 00:1e.0 Intel Corporation 82801 PCI Bridge (rev: 194) 0
11 00:1d.7 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB2 E... 11
12 00:1d.3 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UH... 10
13 00:1d.2 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UH... 5
14 00:1d.1 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UH... 3
15 00:1d.0 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UH... 10
16 00:01.0 Intel Corporation 82865G/PE/P PCI to AGP Control... 0
17 00:00.0 Intel Corporation 82865G/PE/P DRAM Controller/Ho... 0
[admin@1899999] > /system resource irq pr
IRQ OWNER
1 keyboard
2 APIC
3 [usb-uhci]
5 [a5212_pci]
5 [usb-uhci]
5 ether2
8 [rtc]
10 [usb-uhci]
10 [usb-uhci]
11 [a5212_pci]
11 [a5212_pci]
11 ether1
14 IDE 1


regards,
C. G.
 
burkon
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Mon Sep 25, 2006 2:12 pm


11 [a5212_pci]
11 [a5212_pci]
11 ether1
Could this be a IRQ sharing problem?

Ekkehard
 
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chvdr
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Mon Sep 25, 2006 6:06 pm


11 [a5212_pci]
11 [a5212_pci]
11 ether1
Could this be a IRQ sharing problem?

Ekkehard
i don't know is that a problem, usually cards works or not.
suddestions?

regards,
C. G.
 
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dibatech
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Packet loss.

Tue Sep 26, 2006 8:03 pm

Try this
Check in routeros Manual and change the ACK timeout to a static setting.
There is a lookup table.
 
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chvdr
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Re: Packet loss.

Wed Sep 27, 2006 7:44 pm

Try this
Check in routeros Manual and change the ACK timeout to a static setting.
There is a lookup table.
to the ap or to the station?

regards,
C. G.
 
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dibatech
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Thu Sep 28, 2006 8:35 am

Both.
Try rather not to use Turbo mode for longer links.
 
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chvdr
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thanks for the posts

Sun Oct 01, 2006 7:46 pm

hi there,
after a week when i persist with the problem the same misteriously disapeared. the only change here is periodic calibration swiched on (thanks to sten and jarosoup). yesterday we have 0% packet loss for 24 hours.
thank you all for your posts.

regards,
C. G.
 
bushy
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Mon Oct 02, 2006 4:55 am

Maybe disable the USB stuff on the motherboard too ?

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