Wireless Access

We have a network of AP-175s. The far end AP-175 has a camera attached to its ethernet port. It is using 5 GHz to get back to the head end. The head end AP-175 is connected to a S3500 switch with a 3200 controller. We were getting distorted video over the connection. We removed the Cat 5E rated lightning supressor from the Cat 5E cable feeding the head end AP-175 and the video came clear. We have tried a few different models with the same result. The camera vendor said they have used the same lightning suppresors on other wireless installations (Firetide) with success.

Is there anything unique with the AP-175 for using lightning suppresors on the ethernet feed?

#3200

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jim.mcmanaman@bell.ca wrote:

We have a network of AP-175s. The far end AP-175 has a camera attached to its ethernet port. It is using 5 GHz to get back to the head end. The head end AP-175 is connected to a S3500 switch with a 3200 controller. We were getting distorted video over the connection. We removed the Cat 5E rated lightning supressor from the Cat 5E cable feeding the head end AP-175 and the video came clear. We have tried a few different models with the same result. The camera vendor said they have used the same lightning suppresors on other wireless installations (Firetide) with success.

Is there anything unique with the AP-175 for using lightning suppresors on the ethernet feed?

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- What is the distance between the AP-175s?

- What height are they mounted?

- What external antennas are you using for meshing?

- What band are you using for the mesh?

Its really nothing to do with the physical layout of the APs as the video is perfect until we put on a lightning suppresor on the ethernet cable. But, the Aps are at 50 feet high, 200 meters apart, using Omnis at the head end and 30 degree directional at the far end.

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jim.mcmanaman@bell.ca wrote:

Its really nothing to do with the physical layout of the APs as the video is perfect until we put on a lightning suppresor on the ethernet cable. But, the Aps are at 50 feet high, 200 meters apart, using Omnis at the head end and 30 degree directional at the far end.

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Jim.mcmanaman,

 

Thank you.  Have you tried lightning suppressors on the antennas instead?  Honestly, I have no experience with lightning suppressors on the ethernet cable, since we usually place them on the antennas, since the ethernet is usually ruggedized.

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jim.mcmanaman@bell.ca wrote:

Its really nothing to do with the physical layout of the APs as the video is perfect until we put on a lightning suppresor on the ethernet cable. But, the Aps are at 50 feet high, 200 meters apart, using Omnis at the head end and 30 degree directional at the far end.

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jim.mcmanaman@bell.ca,

 

Here is what our outdoor expert says:

 

 

1)      Outdoors should always use outdoor grade shielded cable

2)      Both camera and AP should have low impedance path to ground.

3)      If the length is 2m or less you can safely eliminate the surge protector.

Okay,

 

And to directly answer your question:  http://www.l-com.com/content/Ethernet_Surge_Protectors.html

 

"The use of a surge protector on an Ethernet line is not without its consequences however. All Ethernet surge protectors will degrade the performance of the Ethernet line. The use of protective components that inherently have a capacitive component as well as the limitations of PCB layout techniques contribute to the degradation. The degradation is in the form of increases in line insertion loss, phase distortion, crosstalk, degraded common mode rejection, and possible ground loops. The use of two protectors on each end of the line will provide protection for each end against surges, at the cost of increased line loss and the possibility of introducing a ground loop into the line."

 

Thank you, as an RCDD I understand all of that. The factremains that they ssaid they use them with Firetide products all the time without this problem occuring. Should we lock the S3500 switch down to 100Mbps on the interface?

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jim.mcmanaman@bell.ca wrote:

Thank you, as an RCDD I understand all of that. The factremains that they ssaid they use them with Firetide products all the time without this problem occuring. Should we lock the S3500 switch down to 100Mbps on the interface?

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jim.mcmanaman@bell.ca,

 

Locking the S3500 speed and duplex down will not eliminate the issues mentioned, but you can certainly try it.  We do not test with ethernet surge protectors and/or with firetide so we cannot confirm or deny what was said.

Also, what model Firetide APs are being used and are they being powered over the ethernet or from AC power? From what I've seen they are all mostly 802.3af, while the 175s are 802.3at. The higher power may exacerbate the issue (if it's power filtering related). If the firetide APs they have seen work before are 802.3af and 10/100, while we are 802.3at at 1gig, it's not apples to apples. I'd be curious of the functional differences between the Firetide devices the vendor claims are without issue compared to the 175s, to see if it's more medium related. 

 

Do you happen to have the make/model of the surge devices used by chance?

Its not a power filtering problem as we are using the AP-175AC, so no PoE involved. Here is his comment:

We have attempted to use two different models of Ditek devices (DTK-MRJPOE and DTK-PVPIP).  In both cases, the Ethernet signal was severely impeded making it impossible to view camera images.

I've never seen those two but they look to be compatible. I've seen other customers' deployments with 175Ps and surge protectors and we are doing 3 cameras of backhaul with no issues. Not sure if maybe something isn't grounded, or if there's some other physical issue. You might open a TAC case and see if they have seen other instances with suppressors on the ethernet line.

Would you be able to provide the brand and part number of surge protectors you have had success with?

I've seen the APC units deployed on some sites. The other one I saw on MSR2Ks was from L-Com, was a silver box, fairly non-descript. I will see if I can dig it out once I get back to good internet with the laptop. something like this though...

http://www.l-com.com/surge-protector-indoor-10-100-1000-base-t-shielded-cat6-lightning-protector-rj45-jacks

it is a known affect though that ethernet surge supression can restrict ethernet performance, moreso the longer the ethernet runs and/or when unshielded cable is used.