MarginalLinks

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Good SNR with bad Packet loss
I did the obvious check for interference and we turned off anything that could remotely affect the signal at the member's house, but no luck. There are no other AP in sight either. The 19db rootenna is a directional panel, I agree it is a little oversize, the smaller rootenna would have been sufficient. From the answers I got, I will do the following: - set the minsig to 60 on all mesh nodes and remove the permanent blocks. Although last time I did that I ran into some problems. - replace the radio in the gateway. - if this does not solve it, I will replace the rootenna at the member with something else TBD.

> Just a few thoughts about this, 19db seems to be quite a big antenna for what should be an easy link. I am thinking of Kenny's issues a few months ago, when he discovered that biggest is not always best where antenna are concerned, but given that this used to be a good link, something must have changed in the environment. You've already checked the radio, so its probably safe to assume that this is OK. This problem would seem to have all the symptoms of interefence, e.g packets being re-transmittted, becasue the first one has not got through. Your customer has not just purchased one of those video senders has he? I assume that neighbour status, or netstumbler does not throw up any more access points. If it had been a bit later in the year, then I might have suspected a growth spurt in the trees which is now intruding into the shot. I would be tempted to change the antenna to something small, but fairly directional. The issue with high gain antenna, is that they are fine if you have the only wireless in the area (rare), but a high gain antenna will pick up sources of interefence over a much larger geographical area. Just one more possibility that has occurrred to me, could the packet loss be taking place in the UTP betweeen the radio and the client?

I use permanent blocks to remove marginal connections... all my (routed) node to node connections are over 60... but I will add the minsig of 60 instead of the permanent block to see if this solves the problem. This particular member used to have a good connection a week ago and the SNR is still good... but all of a sudden, massive packet loss...

>>    If you set the minsig to 60, you will drop all marginal connections. >>    Marginal will cause you much pain in wifi. >>>    One of our wireless coop member is about a half mile away from our >>>    gateway with a reasonable line of sight except for the top of some trees. >>> >>>    The gateway is an AirMatrix Mesh node running MeshAP Pro with a Senao >>>    NL-2511MP to a 12dB omni, the member uses a Senao CB3 Plus inside a 19dB >>>    rootenna. >>> >>>    As we speak the gateway reports: >>> >>>        s-79/n-92 tx@11/0mb~0/0,0,0,0 rx@11/0mb~0/300,0,200,0 >>>        >>>     This looks like a perfect connection with 13dB of SNR running at 11Mb/s... >>> >>>    Unfortunately, as soon as the member uses the wireless, the connection >>>    speed drops to 1Mb/s (which by itself is not really that bad) but there >>>    is significant packet loss causing the connection to be unusable. >>> >>>    I tried everything: >>> >>>    - replaced the bridge in the rootenna >>>    - changed many parameters in the gateway settings (although other >>>     members connect without problems from further away with less powerful >>>     antennas) >>>    - checked for interference both at the gateway and at the member location >>>    - disconnected all cordless phones, etc... >>> >>>    This is a total puzzle. >>> >>>    I had problems like this in the past but running the repeaters in >>>     txpower auto (instead of 200mw) solved most of them. >>> >>>    This time there is a great SNR and a lot of packet loss. What could >>>    cause this? >>> >>>    I suspect: >>> >>>    - a bad radio in the gateway, but many other members connect without >>>    problem. >>>    - a bad rootenna a the customer site, I replaced the bridge inside it, >>>    but not the antenna itself. >>>    - some interference that I did not detect, we don't own a spectrum analyzer. >>> >>>    Please help as the member is becoming more and more frustrated with our >>>    system.

I think may want to look at the radio to client  "Just one more possibility that has occurred to me, could the packet loss be taking place in the UTP between the radio and the client ?"

We have not had any rain for 6 months, so we had a customer that was working fine for several months. Then all of a sudden we started having speed problems. The radio had a great connection. To make a long story short we went out to the house found that our installer had decided to lay the cat5 cable in a gutter. We had a rain storm the week before and the gutter was full of water. The cat5 cable was not in the best of shape look like he had reused it several times. Replaced the cable, ran it inside and problem was fixed.

I did the obvious check for interference and we turned off anything that could remotely affect the signal at the member's house, but no luck. There are no other AP in sight either.

The 19db rootenna is a directional panel, I agree it is a little oversize, the smaller rootenna would have been sufficient.

From the answers I got, I will do the following:

- set the minsig to 60 on all mesh nodes and remove the permanent blocks. Although last time I did that I ran into some problems. - replace the radio in the gateway. - if this does not solve it, I will replace the rootenna at the member with something else TBD.

thinking of Kenny's issues a few months ago, when he discovered that biggest is not always best where antenna are concerned, but given that this used to be a good link, something must have changed in the environment.

You've already checked the radio, so its probably safe to assume that this is OK.

This problem would seem to have all the symptoms of interefence, e.g packets being re-transmittted, becasue the first one has not got through. Your customer has not just purchased one of those video senders has he? I assume that neighbour status, or netstumbler does not throw up any more access points.

If it had been a bit later in the year, then I might have suspected a growth spurt in the trees which is now intruding into the shot.

I would be tempted to change the antenna to something small, but fairly directional. The issue with high gain antenna, is that they are fine if you have the only wireless in the area (rare), but a high gain antenna will pick up sources of interefence over a much larger geographical area.

Just one more possibility that has occurrred to me, could the packet loss be taking place in the UTP betweeen the radio and the client ?

Just a few thoughts, to try and identify

I use permanent blocks to remove marginal connections... all my (routed) node to node connections are over 60... but I will add the minsig of 60 instead of the permanent block to see if this solves the problem.

This particular member used to have a good connection a week ago and the SNR is still good... but all of a sudden, massive packet loss... If you set the minsig to 60, you will drop all marginal connections. Marginal will cause you much pain in wifi. One of our wireless coop member is about a half mile away from our gateway with a reasonable line of sight except for the top of some trees. The gateway is an AirMatrix Mesh node running MeshAP Pro with a Senao  NL-2511MP to a 12dB omni, the member uses a Senao CB3 Plus inside a 19dB  rootenna.

As we speak the gateway reports:

s-79/n-92 tx@11/0mb~0/0,0,0,0 rx@11/0mb~0/300,0,200,0

This looks like a perfect connection with 13dB of SNR running at 11Mb/s...

Unfortunately, as soon as the member uses the wireless, the connection speed drops to 1Mb/s (which by itself is not really that bad) but there is significant packet loss causing the connection to be unusable.

I tried everything:

- replaced the bridge in the rootenna - changed many parameters in the gateway settings (although other                                   members connect without problems from further away with less powerful                                    antennas) - checked for interference both at the gateway and at the member location - disconnected all cordless phones, etc...

This is a total puzzle.

I had problems like this in the past but running the repeaters in                                   txpower auto (instead of 200mw) solved most of them.

This time there is a great SNR and a lot of packet loss. What could cause this?

I suspect:

- a bad radio in the gateway, but many other members connect without problem. - a bad rootenna a the customer site, I replaced the bridge inside it, but not the antenna itself. - some interference that I did not detect, we don't own a spectrum analyzer.

Please help as the member is becoming more and more frustrated with our system.

I did the obvious check for interference and we turned off anything that could remotely affect the signal at the member's house, but no luck. There are no other AP in sight either. The 19db rootenna is a directional panel, I agree it is a little oversize, the smaller rootenna would have been sufficient. From the answers I got, I will do the following: - set the minsig to 60 on all mesh nodes and remove the permanent blocks. Although last time I did that I ran into some problems. - replace the radio in the gateway. - if this does not solve it, I will replace the rootenna at the member with something else TBD.

> Just a few thoughts about this, 19db seems to be quite a big antenna for what should be an easy link. I am thinking of Kenny's issues a few months ago, when he discovered that biggest is not always best where antenna are concerned, but given that this used to be a good link, something must have changed in the environment. > > You've already checked the radio, so its probably safe to assume that this is OK. > > This problem would seem to have all the symptoms of interefence, e.g packets being re-transmittted, becasue the first one has not got through. Your customer has not just purchased one of those video senders has he? I assume that neighbour status, or netstumbler does not throw up any more access points. > > If it had been a bit later in the year, then I might have suspected a growth spurt in the trees which is now intruding into the shot. > > I would be tempted to change the antenna to something small, but fairly directional. The issue with high gain antenna, is that they are fine if you have the only wireless in the area (rare), but a high gain antenna will pick up sources of interefence over a much larger geographical area. > > Just one more possibility that has occurrred to me, could the packet loss be taking place in the UTP betweeen the radio and the client ? > > Just a few thoughts, to try and identify

>    I use permanent blocks to remove marginal connections... all my (routed) node to node connections are over 60... but I will add the minsig of 60 instead of the permanent block to see if this solves the problem. > >    This particular member used to have a good connection a week ago and the SNR is still good... but all of a sudden, massive packet loss... > >        Benoit >>    If you set the minsig to 60, you will drop all marginal connections. >>    Marginal will cause you much pain in wifi. >>      >>>     One of our wireless coop member is about a half mile away from our >>>    gateway with a reasonable line of sight except for the top of some trees. >>> >>>    The gateway is an AirMatrix Mesh node running MeshAP Pro with a Senao >>>    NL-2511MP to a 12dB omni, the member uses a Senao CB3 Plus inside a 19dB >>>    rootenna. >>> >>>    As we speak the gateway reports: >>> >>>        s-79/n-92 tx@11/0mb~0/0,0,0,0 rx@11/0mb~0/300,0,200,0 >>>        >>>     This looks like a perfect connection with 13dB of SNR running at 11Mb/s... >>> >>>    Unfortunately, as soon as the member uses the wireless, the connection >>>    speed drops to 1Mb/s (which by itself is not really that bad) but there >>>    is significant packet loss causing the connection to be unusable. >>> >>>    I tried everything: >>> >>>    - replaced the bridge in the rootenna >>>    - changed many parameters in the gateway settings (although other >>>     members connect without problems from further away with less powerful >>>     antennas) >>>    - checked for interference both at the gateway and at the member location >>>    - disconnected all cordless phones, etc... >>> >>>    This is a total puzzle. >>> >>>    I had problems like this in the past but running the repeaters in >>>     txpower auto (instead of 200mw) solved most of them. >>> >>>    This time there is a great SNR and a lot of packet loss. What could >>>    cause this? >>> >>>    I suspect: >>> >>>    - a bad radio in the gateway, but many other members connect without >>>    problem. >>>    - a bad rootenna a the customer site, I replaced the bridge inside it, >>>    but not the antenna itself. >>>    - some interference that I did not detect, we don't own a spectrum analyzer. >>> >>>    Please help as the member is becoming more and more frustrated with our >>>    system.