Range Extender

Here is the scenario: We have installed remote power monitors on a primary feed (13,200 VAC) to a major hospital complex. It is measuring overall usag e, demand, momentary usage (3 seconds for graphing purposes), peaks and sur ges. The idea is that it may be remotely monitored. As it happens, it is ju st a bit too far from the nearest node to be reliable.

The installer purchased a range-extender (Cisco). The range extender will c onnect to the local WiFi just fine. Various "things" will connect to the ra nge extender, just fine. Those things, when connected directly to a node op erate just fine. Those things when attempting to connect through the range extender act blocked - "No Internet Connection".

The system is unsecured, all security, firewalls and so forth must be softw are based and resident on the individual computers.

Is there an easy or obvious solution? I am not the installer, I did not con ceive or design the system, I am merely asking on his behalf based on what he is reporting. However, I will be one of the end-users.

Thanks in advance!

Peter Wieck Melrose Park, PA

Reply to
peterwieck33
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Wi-Fi range extenders, also known as store and forward repeaters, and range extenders, can be made to work, but only under limited conditions and topologies. My comments also apply to mesh networks and WDS networks, which are range extenders with the addition of an IP routing protocol.

I've had quite a bit of experience ripping such abominations out and replacing them with other solutions. I can explain in detail, but I'm busy right now. Bug me in a few days.

I once gave a talk on the subject of repeaters. Here are my disorganized notes on the topic: To illustrate the effect, I took a simple 2.4 wireless link, and ran iPerf (actually Jperf) to measure the maximum throughput through the wireless link. Slides for 802.11g (2.4Ghz) without a range extender: The average throughput was 42 to 61 Mbits/sec average. I then powered on a pre-configured Linksys RE-2000 range extender and got this mess: with an average throughput of zero to 24 Mbits/sec. If I turn off the range extender, and the speeds return to normal. You can easily reproduce the effect with a simple wireless router or access point, a client computah, and Jperf: Be careful NOT to mix version 2 and 3 of iPerf and Jperf, which are incompatible.

If you don't want to setup iPerf or Jperf, then just use ping. Without the repeater, just ping the local access point continously using some kind of ping that displays sequence numbers such as hrping: Ping away merrily and hopefully, you'll only have a few dropped packets. Then, turn on the repeater and ping away merrily again. If I'm right, you'll see a dramatic increase in dropped packets. Be sure to try the -M option (tx/rx times).

Nope. The obvious start point is to get ride of generic store and forward repeaters. If you must use repeaters, build a proper mesh network, with proper routing, not something that just repeats EVERYTHING that it hears, which is little better than a jammer. Because there are to paths between the source and designation of every packed (direct and through the repeater), you're going to have collisions no matter how you build it. It's those collisions that are preventing reliable connections between devices.

The right answer is either large number of wireless access points, connected together with a switch, and not using an in-band backhaul. Take a look at how hotels and such handle a large number of access points and clients.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

What's the make and model of the RE?

Reply to
Mike S

Think of a PLC solution.

Reply to
Look165

Wow, I've never observed (above ground) anything like on a medium voltage (MV) AC distribution line. Just MV-LV distribution transformers, disconnect switches, circuit breakers and power factor correction caps. (We use 34.5/19.9 kV in my area). Extremely dangerous if mishandled. Sincerely,

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J. B. Wood	            e-mail: arl_123234@hotmail.com
Reply to
J.B. Wood

Cisco-Linksys

White device, two antenna, direct plug-in.

Beyond which I do not know.

Peter Wieck Melrose Park, PA

Reply to
peterwieck33

My guess(tm) would be Linksys RE6300, RE6400, or RE6700: The problem with a wall mounted solution is that the antennas are in a terrible location for best coverage. They should be up as high as possible and away from any metal objects. These repeaters are made for installation convenience, not performance.

Incidentally, if they say Cisco on the box, they're at least 3 years old. Belkin bought Linksys from Cisco in about 2013. The purchase of Belkin by Foxconn is awaiting regulatory approval.

Someone mentioned power line networking. In a sub-station, you want as much air-gap isolation from the lines as possible. That leaves wireless, FSO (free space optics), and fiberoptics as the available options.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

It was plugged into a high outlet just under the ceiling and line-of-sight, perhaps 30 feet from the node. Keep in mind that this is a hospital basement built in the 1930s before any sort of computing of any nature. The footprint is an entire city block.

We are thinking that the main router has some means of blocking these things out. Is that possible? The nodes are all hard-wired.

Reply to
peterwieck33

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