Wireless Issue

I have had a wireless network for about the last 3.5 years - working
very well. However, in the last several months I have noticed an issue
that I have been unable to diagnose. My setup is as follows:

1. Belkin 7230-4 router ( this recently replaced a similar model because
of the observed "problem". The new router also sees this issue). I
assign IP's manually.
2. Several laptops using Belkin wireless cards (win98se, and winxp pro
machines)
3.A wired desktop machine.
4. I use WEP
5. I am running on a channel that is not crowded with other AP's - the
problem seems to be independent of the channel.
6. The SNR as reported by the Belkin utility and Netstumbler is
excellent - typically the signal is at -33dbm and the noise at -82dbm
7. I have tried both the Belkin client and WZC to manage the connection
- the issue still shows up.
8. I have a cordless phone which operates solely in the 5.8GHZ band.
9. The laptop (winxp pro) that primarily sees this issue is only about
10 feet away from the router. I am using the Belkin PC card in it and
have also swapped the card with another identical one which I have, but
the issue still persists.

The problem is that at random times (up to several weeks between
incidents), my link rate will start to drop from 54mps down to 5.5mps
(and lower) and then proceed to bounce around. During these periods, the
SNR also bounces around but is always at a very good level. No other
networks show when I do a site survey.

It would seem that this is an interference problem, but I don't see any
evidence of it (i.e., SNR as indicated by Netstumbler and the Belkin
utility are always good).

So, any ideas as to what may be causing this issue?

Thanks,
Harvey

Harvey Gratt <(E-Mail Removed)> hath wroth:

>1. Belkin 7230-4 router ( this recently replaced a similar model because
>of the observed "problem". The new router also sees this issue).

<http://catalog.belkin.com/IWCatProductPage.process?Merchant_Id=&Section_Id=2 01522&pcount=&Product_Id=136493>
What is the model number of the new router?

>2. Several laptops using Belkin wireless cards (win98se, and winxp pro
>machines)

Do ALL these laptops see the same problem?

>5. I am running on a channel that is not crowded with other AP's - the
>problem seems to be independent of the channel.

Many sources of interference are also independent of channel number.
For example, Frequency Hopping Spread Spectrum cordless phones will
trash the entire 2.4GHz band.

>6. The SNR as reported by the Belkin utility and Netstumbler is
>excellent - typically the signal is at -33dbm and the noise at -82dbm

That's the SNR at the client, not at the Belkin wireless router. If
the interference was heard only by the router and not by the client,
you would not see anything. What SNR does the Belkin router display?

Is this measurement when it operates normally or when you see the
speed variations?

>9. The laptop (winxp pro) that primarily sees this issue is only about
>10 feet away from the router.

Do the other laptops see the problem?

>I am using the Belkin PC card in it and
>have also swapped the card with another identical one which I have, but
>the issue still persists.

Model number of the Belkin PC card?

>The problem is

Hint: First describe the problem you're having, then add your
equipment list, and last add the detail. It's kinda odd reading the
description in reverse order.

>that at random times (up to several weeks between
>incidents),

Random? Well, lets see if it has a pattern.
1. How long does the speed reduction last? (Shortest and longest).
2. How often does the speed reduction last? Shortest interval and
longest interval).
3. How severe? What effects do you see? All laptops or just one?
4. Do the speed reductions coincide with meals?
5. Do the clients disconnect or merely slow down?
6. How are you measuring the connection speed? While traffic is
moving?

>my link rate will start to drop from 54mps down to 5.5mps
>(and lower) and then proceed to bounce around. During these periods, the
>SNR also bounces around but is always at a very good level. No other
>networks show when I do a site survey.

That's normal for interference. However, you should see a decrease in
SNR when the radios hear interference. The idea is that lower speeds
require a smaller SNR to operate. By the numbers:

Speed Min Modulation Typical Noise
Eb/No Sensit Floor
mb/sec dB dBm dBm
11 7.0 CCK -82 -89
5.5 6.0 CCK -85 -91
2 1.6 DQPSK -86 -87.6
1 -3.0 DBPSK -89 -86

54 24.6 64QAM/OFDM -71 -95.6
48 24.1 64QAM/OFDM -71 -95
36 18.8 16QAM/OFDM -78 -96.8
24 17.0 16QAM/OFDM -79 -96
18 10.8 QPSK/OFDM -82 -92.8
12 9.0 QPSK/OFDM -84 -93
9 7.8 BPSK/OFDM -87 -94.8
6 6.0 BPSK/OFDM -88 -94

At 54Mbits/sec, you'll need at least a 24.6dB SNR. At 11Mbits/sec the
system will work with 6.0dB SNR.

However, the usual criteria for causing a slow down is NOT the value
of the SNR. It's the bit error rate. When the data coming through
the system starts generating errors, the access point will slow things
down until the error rate improves. Such increases in error rate do
NOT necessarily require interference or a corresponding decrease in
SNR. It can be caused by oversized or "unusual" packets. I once did
some wireless router exploits testing that included some of these
"unusual" packets there were crafted to hang or crash the router. It
did just that on some ancient models. However, I also noticed that if
the test were through a wireless connection, the connection would slow
down to 1Mbit/sec before crashing the router. That's the way it's
suppose to work. Slow down until the error rate improves. If it
doesn't improve, go even slower until you hit bottom. After that,
disconnect or crash.

Incidentally, try this exploits test on your router:
<http://www.pcflank.com/exploits.htm>
over a wireless link. It hangs my BEFW11S4v4 and some other older
routers. Check what it does to the SNR during the test.

>It would seem that this is an interference problem, but I don't see any
>evidence of it (i.e., SNR as indicated by Netstumbler and the Belkin
>utility are always good).

Interference usually shows up as a decrease in SNR. However, there's
no guarantee that what's causing your problem is interference or that
whatever interference you're seeing is causing the speed reduction.
There's also no guarantee that your client computers are acting sanely
in the presence of interference. For example, some Intel MiniPCI
cards with Proset 9.x would slow down to 1Mbit/sec and stay there
forever.

>So, any ideas as to what may be causing this issue?

No, not really. There really isn't enough info to make an intelligent
guess. I would need to know more about the effects of the
interference and a much better description as to the pattern. When
faced with the same problem, I usually dig out the spectrum analyzer
and monitoring (SNMP based) software. There's quite a bit that can be
learned from both. For example, if your interference problem
coincides with meal times, look for a leaky microwave oven.

See list of probable culprits at:
<http://wireless.wikia.com/wiki/Wi-Fi#Interference>


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

A very comprehensive reply!! I'll try to provide some more information.

1. The original router was a Belkin f5d7230-4, v1111. The replacement
router is a Belkin f5d7230-4, v6002.

2. The pc cards are Belkin f5d7010, original version.

3. Current router and pc cards are using the latest available firmware.

4. I do believe that all the laptops see the issue - it does appear to
originate at the router. Also my cordless phone was not in use and is a
5.8MHZ phone.

5. The current router ran for about 3 weeks before I saw the problem.
The incident happened last night around 9:00pm and lasted for 2 hrs.
at which time I shut down and went to bed.
More than one laptop was affected.
Speed reduction was noted by the WZC and Belkin utilities. I also
conducted the Verizon FIOS speedtest and confirmed that the degradation
was real.
No disconnects occurred - only a slowdown. The Client SNR was still
good but was more erratic than usual (signal -35dbm, noise -82dbm).
I have never been able to correlate the issue with any known time
or event
6. How do I measure the router SNR? I don't see a way for the router to
display this information.
7. Will the exploit task trash my router/system?

Thanks,
Harvey


Jeff Liebermann wrote:
> Harvey Gratt <(E-Mail Removed)> hath wroth:
>
>
>> 1. Belkin 7230-4 router ( this recently replaced a similar model because
>> of the observed "problem". The new router also sees this issue).
>>
>
> <http://catalog.belkin.com/IWCatProductPage.process?Merchant_Id=&Section_Id=2 01522&pcount=&Product_Id=136493>
> What is the model number of the new router?
>
>
>> 2. Several laptops using Belkin wireless cards (win98se, and winxp pro
>> machines)
>>
>
> Do ALL these laptops see the same problem?
>
>
>> 5. I am running on a channel that is not crowded with other AP's - the
>> problem seems to be independent of the channel.
>>
>
> Many sources of interference are also independent of channel number.
> For example, Frequency Hopping Spread Spectrum cordless phones will
> trash the entire 2.4GHz band.
>
>
>> 6. The SNR as reported by the Belkin utility and Netstumbler is
>> excellent - typically the signal is at -33dbm and the noise at -82dbm
>>
>
> That's the SNR at the client, not at the Belkin wireless router. If
> the interference was heard only by the router and not by the client,
> you would not see anything. What SNR does the Belkin router display?
>
> Is this measurement when it operates normally or when you see the
> speed variations?
>
>
>> 9. The laptop (winxp pro) that primarily sees this issue is only about
>> 10 feet away from the router.
>>
>
> Do the other laptops see the problem?
>
>
>> I am using the Belkin PC card in it and
>> have also swapped the card with another identical one which I have, but
>> the issue still persists.
>>
>
> Model number of the Belkin PC card?
>
>
>> The problem is
>>
>
> Hint: First describe the problem you're having, then add your
> equipment list, and last add the detail. It's kinda odd reading the
> description in reverse order.
>
>
>> that at random times (up to several weeks between
>> incidents),
>>
>
> Random? Well, lets see if it has a pattern.
> 1. How long does the speed reduction last? (Shortest and longest).
> 2. How often does the speed reduction last? Shortest interval and
> longest interval).
> 3. How severe? What effects do you see? All laptops or just one?
> 4. Do the speed reductions coincide with meals?
> 5. Do the clients disconnect or merely slow down?
> 6. How are you measuring the connection speed? While traffic is
> moving?
>
>
>> my link rate will start to drop from 54mps down to 5.5mps
>> (and lower) and then proceed to bounce around. During these periods, the
>> SNR also bounces around but is always at a very good level. No other
>> networks show when I do a site survey.
>>
>
> That's normal for interference. However, you should see a decrease in
> SNR when the radios hear interference. The idea is that lower speeds
> require a smaller SNR to operate. By the numbers:
>
> Speed Min Modulation Typical Noise
> Eb/No Sensit Floor
> mb/sec dB dBm dBm
> 11 7.0 CCK -82 -89
> 5.5 6.0 CCK -85 -91
> 2 1.6 DQPSK -86 -87.6
> 1 -3.0 DBPSK -89 -86
>
> 54 24.6 64QAM/OFDM -71 -95.6
> 48 24.1 64QAM/OFDM -71 -95
> 36 18.8 16QAM/OFDM -78 -96.8
> 24 17.0 16QAM/OFDM -79 -96
> 18 10.8 QPSK/OFDM -82 -92.8
> 12 9.0 QPSK/OFDM -84 -93
> 9 7.8 BPSK/OFDM -87 -94.8
> 6 6.0 BPSK/OFDM -88 -94
>
> At 54Mbits/sec, you'll need at least a 24.6dB SNR. At 11Mbits/sec the
> system will work with 6.0dB SNR.
>
> However, the usual criteria for causing a slow down is NOT the value
> of the SNR. It's the bit error rate. When the data coming through
> the system starts generating errors, the access point will slow things
> down until the error rate improves. Such increases in error rate do
> NOT necessarily require interference or a corresponding decrease in
> SNR. It can be caused by oversized or "unusual" packets. I once did
> some wireless router exploits testing that included some of these
> "unusual" packets there were crafted to hang or crash the router. It
> did just that on some ancient models. However, I also noticed that if
> the test were through a wireless connection, the connection would slow
> down to 1Mbit/sec before crashing the router. That's the way it's
> suppose to work. Slow down until the error rate improves. If it
> doesn't improve, go even slower until you hit bottom. After that,
> disconnect or crash.
>
> Incidentally, try this exploits test on your router:
> <http://www.pcflank.com/exploits.htm>
> over a wireless link. It hangs my BEFW11S4v4 and some other older
> routers. Check what it does to the SNR during the test.
>
>
>> It would seem that this is an interference problem, but I don't see any
>> evidence of it (i.e., SNR as indicated by Netstumbler and the Belkin
>> utility are always good).
>>
>
> Interference usually shows up as a decrease in SNR. However, there's
> no guarantee that what's causing your problem is interference or that
> whatever interference you're seeing is causing the speed reduction.
> There's also no guarantee that your client computers are acting sanely
> in the presence of interference. For example, some Intel MiniPCI
> cards with Proset 9.x would slow down to 1Mbit/sec and stay there
> forever.
>
>
>> So, any ideas as to what may be causing this issue?
>>
>
> No, not really. There really isn't enough info to make an intelligent
> guess. I would need to know more about the effects of the
> interference and a much better description as to the pattern. When
> faced with the same problem, I usually dig out the spectrum analyzer
> and monitoring (SNMP based) software. There's quite a bit that can be
> learned from both. For example, if your interference problem
> coincides with meal times, look for a leaky microwave oven.
>
> See list of probable culprits at:
> <http://wireless.wikia.com/wiki/Wi-Fi#Interference>
>
>
>

Forgot to mention that, so far today, the problem has not occurred. I've
been online for several hours.

Harvey

Harvey Gratt wrote:
> A very comprehensive reply!! I'll try to provide some more information.
>
> 1. The original router was a Belkin f5d7230-4, v1111. The replacement
> router is a Belkin f5d7230-4, v6002.
>
> 2. The pc cards are Belkin f5d7010, original version.
>
> 3. Current router and pc cards are using the latest available firmware.
>
> 4. I do believe that all the laptops see the issue - it does appear to
> originate at the router. Also my cordless phone was not in use and is
> a 5.8MHZ phone.
>
> 5. The current router ran for about 3 weeks before I saw the problem.
> The incident happened last night around 9:00pm and lasted for 2
> hrs. at which time I shut down and went to bed.
> More than one laptop was affected.
> Speed reduction was noted by the WZC and Belkin utilities. I also
> conducted the Verizon FIOS speedtest and confirmed that the
> degradation was real.
> No disconnects occurred - only a slowdown. The Client SNR was
> still good but was more erratic than usual (signal -35dbm, noise -82dbm).
> I have never been able to correlate the issue with any known time
> or event
> 6. How do I measure the router SNR? I don't see a way for the router
> to display this information.
> 7. Will the exploit task trash my router/system?
>
> Thanks,
> Harvey
>
> Jeff Liebermann wrote:
>> Harvey Gratt <(E-Mail Removed)> hath wroth:
>>
>>
>>> 1. Belkin 7230-4 router ( this recently replaced a similar model
>>> because of the observed "problem". The new router also sees this
>>> issue).
>>>
>>
>> <http://catalog.belkin.com/IWCatProductPage.process?Merchant_Id=&Section_Id=2 01522&pcount=&Product_Id=136493>
>>
>> What is the model number of the new router?
>>
>>
>>> 2. Several laptops using Belkin wireless cards (win98se, and winxp
>>> pro machines)
>>>
>>
>> Do ALL these laptops see the same problem?
>>
>>
>>> 5. I am running on a channel that is not crowded with other AP's -
>>> the problem seems to be independent of the channel.
>>>
>>
>> Many sources of interference are also independent of channel number.
>> For example, Frequency Hopping Spread Spectrum cordless phones will
>> trash the entire 2.4GHz band.
>>
>>
>>> 6. The SNR as reported by the Belkin utility and Netstumbler is
>>> excellent - typically the signal is at -33dbm and the noise at -82dbm
>>>
>>
>> That's the SNR at the client, not at the Belkin wireless router. If
>> the interference was heard only by the router and not by the client,
>> you would not see anything. What SNR does the Belkin router display?
>>
>> Is this measurement when it operates normally or when you see the
>> speed variations?
>>
>>
>>> 9. The laptop (winxp pro) that primarily sees this issue is only
>>> about 10 feet away from the router.
>>>
>>
>> Do the other laptops see the problem?
>>
>>
>>> I am using the Belkin PC card in it and have also swapped the card
>>> with another identical one which I have, but the issue still persists.
>>>
>>
>> Model number of the Belkin PC card?
>>
>>> The problem is
>>>
>>
>> Hint: First describe the problem you're having, then add your
>> equipment list, and last add the detail. It's kinda odd reading the
>> description in reverse order.
>>
>>
>>> that at random times (up to several weeks between incidents),
>>>
>>
>> Random? Well, lets see if it has a pattern.
>> 1. How long does the speed reduction last? (Shortest and longest).
>> 2. How often does the speed reduction last? Shortest interval and
>> longest interval).
>> 3. How severe? What effects do you see? All laptops or just one?
>> 4. Do the speed reductions coincide with meals?
>> 5. Do the clients disconnect or merely slow down?
>> 6. How are you measuring the connection speed? While traffic is
>> moving?
>>
>>
>>> my link rate will start to drop from 54mps down to 5.5mps (and
>>> lower) and then proceed to bounce around. During these periods, the
>>> SNR also bounces around but is always at a very good level. No other
>>> networks show when I do a site survey.
>>>
>>
>> That's normal for interference. However, you should see a decrease in
>> SNR when the radios hear interference. The idea is that lower speeds
>> require a smaller SNR to operate. By the numbers:
>>
>> Speed Min Modulation Typical Noise
>> Eb/No Sensit Floor
>> mb/sec dB dBm dBm
>> 11 7.0 CCK -82 -89
>> 5.5 6.0 CCK -85 -91
>> 2 1.6 DQPSK -86 -87.6
>> 1 -3.0 DBPSK -89 -86
>>
>> 54 24.6 64QAM/OFDM -71 -95.6
>> 48 24.1 64QAM/OFDM -71 -95
>> 36 18.8 16QAM/OFDM -78 -96.8
>> 24 17.0 16QAM/OFDM -79 -96
>> 18 10.8 QPSK/OFDM -82 -92.8
>> 12 9.0 QPSK/OFDM -84 -93
>> 9 7.8 BPSK/OFDM -87 -94.8
>> 6 6.0 BPSK/OFDM -88 -94
>> At 54Mbits/sec, you'll need at least a 24.6dB SNR. At 11Mbits/sec the
>> system will work with 6.0dB SNR.
>>
>> However, the usual criteria for causing a slow down is NOT the value
>> of the SNR. It's the bit error rate. When the data coming through
>> the system starts generating errors, the access point will slow things
>> down until the error rate improves. Such increases in error rate do
>> NOT necessarily require interference or a corresponding decrease in
>> SNR. It can be caused by oversized or "unusual" packets. I once did
>> some wireless router exploits testing that included some of these
>> "unusual" packets there were crafted to hang or crash the router. It
>> did just that on some ancient models. However, I also noticed that if
>> the test were through a wireless connection, the connection would slow
>> down to 1Mbit/sec before crashing the router. That's the way it's
>> suppose to work. Slow down until the error rate improves. If it
>> doesn't improve, go even slower until you hit bottom. After that,
>> disconnect or crash.
>>
>> Incidentally, try this exploits test on your router:
>> <http://www.pcflank.com/exploits.htm>
>> over a wireless link. It hangs my BEFW11S4v4 and some other older
>> routers. Check what it does to the SNR during the test.
>>
>>
>>> It would seem that this is an interference problem, but I don't see
>>> any evidence of it (i.e., SNR as indicated by Netstumbler and the
>>> Belkin utility are always good).
>>>
>>
>> Interference usually shows up as a decrease in SNR. However, there's
>> no guarantee that what's causing your problem is interference or that
>> whatever interference you're seeing is causing the speed reduction.
>> There's also no guarantee that your client computers are acting sanely
>> in the presence of interference. For example, some Intel MiniPCI
>> cards with Proset 9.x would slow down to 1Mbit/sec and stay there
>> forever.
>>
>>
>>> So, any ideas as to what may be causing this issue?
>>>
>>
>> No, not really. There really isn't enough info to make an intelligent
>> guess. I would need to know more about the effects of the
>> interference and a much better description as to the pattern. When
>> faced with the same problem, I usually dig out the spectrum analyzer
>> and monitoring (SNMP based) software. There's quite a bit that can be
>> learned from both. For example, if your interference problem
>> coincides with meal times, look for a leaky microwave oven.
>>
>> See list of probable culprits at:
>> <http://wireless.wikia.com/wiki/Wi-Fi#Interference>
>>
>>
>>

Harvey Gratt <(E-Mail Removed)> hath wroth:

>A very comprehensive reply!! I'll try to provide some more information.

With all due respect, your information is lacking. I asked a number
of very specific questions. You answered a few, and were fairly vague
with your answers. As a rule of thumb, try supplying numbers, not
generalizations.

>1. The original router was a Belkin f5d7230-4, v1111. The replacement
>router is a Belkin f5d7230-4, v6002.

Ok. I think (not sure) that those are actually two different routers,
with different chipsets. If it happens with both, I guess it's not a
defective router. I'm too lazy to dig out the FCC ID numbers and look
at the internals.

>2. The pc cards are Belkin f5d7010, original version.
>3. Current router and pc cards are using the latest available firmware.

I had quite a bit of entertainment value with those PCMCIA cards. The
"latest" v2 drivers from the web site were trashed. Only the ones
from the original CDROM worked. See:
<http://groups.google.com/group/alt.internet.wireless/browse_thread/thread/d3584928f4c8111e/65cb655f93722650?lnk=st&q=&rnum=1&hl=en#65cb655f93 722650>
I don't recall if this was a problem with the "original version" or
not.

Incidentally, the "latest available firmware" means "I'm too lazy to
find the numbers" which may or may not really be the latest,
especially if there are beta versions available. It's often important
to supply the hardware version (you didn't) and the firmware version
because there are sometimes version specific bugs or problems. I
don't think that's the case here, but it's best to supply the numbers
anyway.

>4. I do believe that all the laptops see the issue

See my previous posting in reference to trying to assign some numbers
to the interference pattern.

>- it does appear to
>originate at the router.

How did you determine that? See my previous postings and questions in
reference to my question on how you located the problem, measured the
SNR, and determined the extent of the problem.

>5. The current router ran for about 3 weeks before I saw the problem.
> The incident happened last night around 9:00pm and lasted for 2 hrs.
>at which time I shut down and went to bed.

That's only one incident. I'm trying to establish a pattern. See my
previous posting and questions on the frequency and extent of the
problem.

Did you do anything during the two hours to try and isolate the
problem? Any SNR measurements? Power cycle the router? Reboot the
laptops? Move antennas around?

> More than one laptop was affected.

Is that 2, 3, 4, or more laptops? Please try to be a bit less vague.

> Speed reduction was noted by the WZC and Belkin utilities. I also
>conducted the Verizon FIOS speedtest and confirmed that the degradation
>was real.

Good. That means that whatever was happening did not drop the
connection or disconnect the session. It's also apparent that most of
the router is still functional. That sure sounds like intereference
to me.

> No disconnects occurred - only a slowdown. The Client SNR was still
>good but was more erratic than usual (signal -35dbm, noise -82dbm).

Any chance one of the other laptops was doing a major download at the
time? Self-interference is a common problem. You will see erratic
signal strength when one of the other laptops is operational.

> I have never been able to correlate the issue with any known time
>or event

Fine. Let me try. All I need is a pattern. If you don't know the
answer, just say that you don't know.

>> Random? Well, lets see if it has a pattern.
>> 1. How long does the speed reduction last? (Shortest and longest).
>> 2. How often does the speed reduction last? Shortest interval and
>> longest interval).
>> 3. How severe? What effects do you see? All laptops or just one?
>> 4. Do the speed reductions coincide with meals?
>> 5. Do the clients disconnect or merely slow down?
>> 6. How are you measuring the connection speed? While traffic is
>> moving?

>6. How do I measure the router SNR? I don't see a way for the router to
>display this information.

It might be in the web based configuration on some manner of status
page. I'm not familiar with this Belkin model and there's no online
configuration simulator. Signal strength indication is not very
common in routers because it has to be displayed by the individual
client connection. For example, see my home router at:
<https://home.learnbydestroying.com:8080/>
The signal level and SNR graphs are at the bottom of the page. (I'll
fix the certificates problem later). You can also extract the numbers
by sniffing the over the air traffic and inspecting the management
packets.

>7. Will the exploit task trash my router/system?

Nope, it's fairly safe. However, it might hang your router. Be
prepared to power cycle the router. If you're not sure, save or
document your router settings before testing.



--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

1. The firmware is the latest as posted on the Belkin website. I even
did file compares since the dates had changed. Remember, my version1 pc
card ( I believe they're up to version 4 now) is many years old - I
doubt Belkin will ever update them. But FWIW, the following is for the
pc cards:
Board: V1799 D7010 Rev. 4.5
Chipset: BCM4306 /BCM2050
Driver Version: 3.30.15.0

2. Problem last night happened with 2 laptops on. Problem remained when
the furthest laptop was turned off. No major downloads by any laptop
were in progress

3. I did reboot the router when I decided to broadcast my SSID to see if
this was an issue - it did not help.

4. The problem is very intermittent, 3 or 4 times with the old router,
and once with this new router. The problem occurred at intervals of one
to several weeks and would last for at least several hours. The client
SNR remains high - signal around -40dbm to -33dbm, noise level around
-80dbm.

5. I cannot deduce a pattern

6. I checked my router's web pages - does not seem to indicate any SNR
information.

7. Since both laptops showed erratic behavior, I assumed the issue was
at the router (interference at the router as you had indicated). This is
just speculation on my part.

8. Before I decide to try it, what will the exploit test show us?

Thanks,
Harvey




Jeff Liebermann wrote:
> Harvey Gratt <(E-Mail Removed)> hath wroth:
>
>
>> A very comprehensive reply!! I'll try to provide some more information.
>>
>
> With all due respect, your information is lacking. I asked a number
> of very specific questions. You answered a few, and were fairly vague
> with your answers. As a rule of thumb, try supplying numbers, not
> generalizations.
>
>
>> 1. The original router was a Belkin f5d7230-4, v1111. The replacement
>> router is a Belkin f5d7230-4, v6002.
>>
>
> Ok. I think (not sure) that those are actually two different routers,
> with different chipsets. If it happens with both, I guess it's not a
> defective router. I'm too lazy to dig out the FCC ID numbers and look
> at the internals.
>
>
>> 2. The pc cards are Belkin f5d7010, original version.
>> 3. Current router and pc cards are using the latest available firmware.
>>
>
> I had quite a bit of entertainment value with those PCMCIA cards. The
> "latest" v2 drivers from the web site were trashed. Only the ones
> from the original CDROM worked. See:
> <http://groups.google.com/group/alt.internet.wireless/browse_thread/thread/d3584928f4c8111e/65cb655f93722650?lnk=st&q=&rnum=1&hl=en#65cb655f93 722650>
> I don't recall if this was a problem with the "original version" or
> not.
>
> Incidentally, the "latest available firmware" means "I'm too lazy to
> find the numbers" which may or may not really be the latest,
> especially if there are beta versions available. It's often important
> to supply the hardware version (you didn't) and the firmware version
> because there are sometimes version specific bugs or problems. I
> don't think that's the case here, but it's best to supply the numbers
> anyway.
>
>
>> 4. I do believe that all the laptops see the issue
>>
>
> See my previous posting in reference to trying to assign some numbers
> to the interference pattern.
>
>
>> - it does appear to
>> originate at the router.
>>
>
> How did you determine that? See my previous postings and questions in
> reference to my question on how you located the problem, measured the
> SNR, and determined the extent of the problem.
>
>
>> 5. The current router ran for about 3 weeks before I saw the problem.
>> The incident happened last night around 9:00pm and lasted for 2 hrs.
>> at which time I shut down and went to bed.
>>
>
> That's only one incident. I'm trying to establish a pattern. See my
> previous posting and questions on the frequency and extent of the
> problem.
>
> Did you do anything during the two hours to try and isolate the
> problem? Any SNR measurements? Power cycle the router? Reboot the
> laptops? Move antennas around?
>
>
>> More than one laptop was affected.
>>
>
> Is that 2, 3, 4, or more laptops? Please try to be a bit less vague.
>
>
>> Speed reduction was noted by the WZC and Belkin utilities. I also
>> conducted the Verizon FIOS speedtest and confirmed that the degradation
>> was real.
>>
>
> Good. That means that whatever was happening did not drop the
> connection or disconnect the session. It's also apparent that most of
> the router is still functional. That sure sounds like intereference
> to me.
>
>
>> No disconnects occurred - only a slowdown. The Client SNR was still
>> good but was more erratic than usual (signal -35dbm, noise -82dbm).
>>
>
> Any chance one of the other laptops was doing a major download at the
> time? Self-interference is a common problem. You will see erratic
> signal strength when one of the other laptops is operational.
>
>
>> I have never been able to correlate the issue with any known time
>> or event
>>
>
> Fine. Let me try. All I need is a pattern. If you don't know the
> answer, just say that you don't know.
>
>
>>> Random? Well, lets see if it has a pattern.
>>> 1. How long does the speed reduction last? (Shortest and longest).
>>> 2. How often does the speed reduction last? Shortest interval and
>>> longest interval).
>>> 3. How severe? What effects do you see? All laptops or just one?
>>> 4. Do the speed reductions coincide with meals?
>>> 5. Do the clients disconnect or merely slow down?
>>> 6. How are you measuring the connection speed? While traffic is
>>> moving?
>>>
>
>
>> 6. How do I measure the router SNR? I don't see a way for the router to
>> display this information.
>>
>
> It might be in the web based configuration on some manner of status
> page. I'm not familiar with this Belkin model and there's no online
> configuration simulator. Signal strength indication is not very
> common in routers because it has to be displayed by the individual
> client connection. For example, see my home router at:
> <https://home.learnbydestroying.com:8080/>
> The signal level and SNR graphs are at the bottom of the page. (I'll
> fix the certificates problem later). You can also extract the numbers
> by sniffing the over the air traffic and inspecting the management
> packets.
>
>
>> 7. Will the exploit task trash my router/system?
>>
>
> Nope, it's fairly safe. However, it might hang your router. Be
> prepared to power cycle the router. If you're not sure, save or
> document your router settings before testing.
>
>
>
>

Harvey Gratt <(E-Mail Removed)> hath wroth:

>1. The firmware is the latest as posted on the Belkin website. I even
>did file compares since the dates had changed. Remember, my version1 pc
>card ( I believe they're up to version 4 now) is many years old - I
>doubt Belkin will ever update them. But FWIW, the following is for the
>pc cards:
>Board: V1799 D7010 Rev. 4.5
>Chipset: BCM4306 /BCM2050
>Driver Version: 3.30.15.0

Belkin does not list the driver version on their web pile. However, I
do note that the date is 1/24/07, which might be a new driver or the
same old one. No way to tell without comparing versions numbers.
<http://www.belkin.com/support/article/?lid=en&pid=F5D7010&aid=6003&scid=221>

Incidentally, this is one reason I don't like Belkin products. There
are usually 1 or possibly 2 firmware updates, followed by nothing.
Eventually, it gets discontinued. Meanwhile, Netgear, Dlink, and
especially Linksys, continue to upgrade and fix problems even on
obsolete products.

>2. Problem last night happened with 2 laptops on. Problem remained when
>the furthest laptop was turned off. No major downloads by any laptop
>were in progress

Ok, so that eliminates my guess that it's your other laptop.

>3. I did reboot the router when I decided to broadcast my SSID to see if
>this was an issue - it did not help.

SSID juggling will not help with what appears to be an interference
problem. However, rebooting the router was useful in case it was
partially hung or insane.

>4. The problem is very intermittent, 3 or 4 times with the old router,
>and once with this new router. The problem occurred at intervals of one
>to several weeks and would last for at least several hours.

If it only happens a few times every several weeks, it's going to be
very difficult to identify. However, I have seen situations exactly
like that. One customer was having a problem that only appeared every
3 weeks. I marked the dates and times on the calendar and found that
it was the same days of the week every time. Eventually, we
discovered that the neighbors had a wireless system (that was not
broadcasting its SSID). The adults used their wired computer.
However, their son was doing the time share routine between houses. He
would arrive with his laptop full of peer to peer file sharing junk,
and promptly setup a server, via wireless. The result was almost
traffic continuous traffic until he disarmed the monster.

If you feel ambitious, download a Linux LiveCD with Kismet and go
looking for such hidden access points.
<http://www.remote-exploit.org/backtrack.html>

>The client
>SNR remains high - signal around -40dbm to -33dbm, noise level around
>-80dbm.

If the interference was only being received by the Belkin router, you
would not see a drop in SNR at the client end. If your Belkin
wireless router is sitting in a window, where it can hear the world,
you might want to move it away to a more protected location.

>5. I cannot deduce a pattern

Deduceing the pattern is my problem. You supply the data.

>6. I checked my router's web pages - does not seem to indicate any SNR
>information.

Bummer. That's one reason I like using DD-WRT firmware. I can get
individual stats on each client, perform scans, tweak settings, etc.
<http://www.dd-wrt.com/wiki/index.php?title=Wl_command>
Most cheap routers lack these troubleshooting features.

>7. Since both laptops showed erratic behavior, I assumed the issue was
>at the router (interference at the router as you had indicated). This is
>just speculation on my part.

It's a fair deduction. We're still not sure it's interference, but I
don't have much in the way of alternatives.

>8. Before I decide to try it, what will the exploit test show us?

I suspected that you might be sending or receiving mal-formed or
mangled packets. These have a detrimental effect on router stability
and might be causing a problem. I'm just guessing but it seems like
an easy and fairly harmless test to try. Try it both wired and
wireless. If it appears to slow down when run via wireless, then it's
possible we may have a suitable culprit.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

1. I believe 1/24/07 date is the one I did a file compare on with the
"latest" version I had installed. The files were identical.

2. My connection has now been on for about 10 hours with no problems.

3. The exploit test was passed with no issues - I selected all of the
exploits. My wireless speeds and connectivity were not hindered.

4. Sorry I can't provide more data wrt a pattern. At this point, I'm
still thinking it's some kind of interference. My router is about 10
feet away from a window and about 5 feet away from an outside wall, so
there could be some issue there. Unfortunately I cannot move it since my
FIOS connection is down the adjacent wall.

Thanks,
Harvey


Jeff Liebermann wrote:
> Harvey Gratt <(E-Mail Removed)> hath wroth:
>
>
>> 1. The firmware is the latest as posted on the Belkin website. I even
>> did file compares since the dates had changed. Remember, my version1 pc
>> card ( I believe they're up to version 4 now) is many years old - I
>> doubt Belkin will ever update them. But FWIW, the following is for the
>> pc cards:
>> Board: V1799 D7010 Rev. 4.5
>> Chipset: BCM4306 /BCM2050
>> Driver Version: 3.30.15.0
>>
>
> Belkin does not list the driver version on their web pile. However, I
> do note that the date is 1/24/07, which might be a new driver or the
> same old one. No way to tell without comparing versions numbers.
> <http://www.belkin.com/support/article/?lid=en&pid=F5D7010&aid=6003&scid=221>
>
> Incidentally, this is one reason I don't like Belkin products. There
> are usually 1 or possibly 2 firmware updates, followed by nothing.
> Eventually, it gets discontinued. Meanwhile, Netgear, Dlink, and
> especially Linksys, continue to upgrade and fix problems even on
> obsolete products.
>
>
>> 2. Problem last night happened with 2 laptops on. Problem remained when
>> the furthest laptop was turned off. No major downloads by any laptop
>> were in progress
>>
>
> Ok, so that eliminates my guess that it's your other laptop.
>
>
>> 3. I did reboot the router when I decided to broadcast my SSID to see if
>> this was an issue - it did not help.
>>
>
> SSID juggling will not help with what appears to be an interference
> problem. However, rebooting the router was useful in case it was
> partially hung or insane.
>
>
>> 4. The problem is very intermittent, 3 or 4 times with the old router,
>> and once with this new router. The problem occurred at intervals of one
>> to several weeks and would last for at least several hours.
>>
>
> If it only happens a few times every several weeks, it's going to be
> very difficult to identify. However, I have seen situations exactly
> like that. One customer was having a problem that only appeared every
> 3 weeks. I marked the dates and times on the calendar and found that
> it was the same days of the week every time. Eventually, we
> discovered that the neighbors had a wireless system (that was not
> broadcasting its SSID). The adults used their wired computer.
> However, their son was doing the time share routine between houses. He
> would arrive with his laptop full of peer to peer file sharing junk,
> and promptly setup a server, via wireless. The result was almost
> traffic continuous traffic until he disarmed the monster.
>
> If you feel ambitious, download a Linux LiveCD with Kismet and go
> looking for such hidden access points.
> <http://www.remote-exploit.org/backtrack.html>
>
>
>> The client
>> SNR remains high - signal around -40dbm to -33dbm, noise level around
>> -80dbm.
>>
>
> If the interference was only being received by the Belkin router, you
> would not see a drop in SNR at the client end. If your Belkin
> wireless router is sitting in a window, where it can hear the world,
> you might want to move it away to a more protected location.
>
>
>> 5. I cannot deduce a pattern
>>
>
> Deduceing the pattern is my problem. You supply the data.
>
>
>> 6. I checked my router's web pages - does not seem to indicate any SNR
>> information.
>>
>
> Bummer. That's one reason I like using DD-WRT firmware. I can get
> individual stats on each client, perform scans, tweak settings, etc.
> <http://www.dd-wrt.com/wiki/index.php?title=Wl_command>
> Most cheap routers lack these troubleshooting features.
>
>
>> 7. Since both laptops showed erratic behavior, I assumed the issue was
>> at the router (interference at the router as you had indicated). This is
>> just speculation on my part.
>>
>
> It's a fair deduction. We're still not sure it's interference, but I
> don't have much in the way of alternatives.
>
>
>> 8. Before I decide to try it, what will the exploit test show us?
>>
>
> I suspected that you might be sending or receiving mal-formed or
> mangled packets. These have a detrimental effect on router stability
> and might be causing a problem. I'm just guessing but it seems like
> an easy and fairly harmless test to try. Try it both wired and
> wireless. If it appears to slow down when run via wireless, then it's
> possible we may have a suitable culprit.
>
>

On Sun, 25 Mar 2007 09:14:49 -0700, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>Harvey Gratt <(E-Mail Removed)> hath wroth:

>>5. I am running on a channel that is not crowded with other AP's - the
>>problem seems to be independent of the channel.
>
>Many sources of interference are also independent of channel number.
>For example, Frequency Hopping Spread Spectrum cordless phones will
>trash the entire 2.4GHz band.

Some will, but not all -- I've found some that use only part of the
band.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_How_To>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>