Re: hub or switch at solar powered POP? in Wireless Service Providers http://www.dslreports.com/forum/r13379385 en Wed, 25 Nov 2009 09:16:37 EDT Wed, 25 Nov 2009 09:16:37 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13429623 BigCreek :
said by John Galt See Profile:

Or this...
That must be the best electrified Outhouse I've ever seen ;-)
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SBC Pro Static DSL; Linux. Terrific wife & kids; live on a farm by Big Creek. Software & network consultant.]]> http://www.dslreports.com/forum/remark,13429623 Tue, 17 May 2005 14:57:43 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13429102 John Galt : Or this...

I like the wind generator. It works when Mr. Sol is hiding 'round the backside.

;)
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A is A
]]> http://www.dslreports.com/forum/remark,13429102 Tue, 17 May 2005 13:53:16 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13428904 John Galt :
said by pmurdock See Profile:

It is an 80 watt panel.. I may just want to add another panel.. :)
I was going to suggest that...!

;)
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A is A]]> http://www.dslreports.com/forum/remark,13428904 Tue, 17 May 2005 13:26:36 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13427061 pmurdock : It is an 80 watt panel.. I may just want to add another panel.. :)

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13427061 Tue, 17 May 2005 09:26:05 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13425073 John Galt : That reminds me...

How many watts is your panel?
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A is A]]> http://www.dslreports.com/forum/remark,13425073 Mon, 16 May 2005 23:35:43 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13424594 jdmarti1 : What kind of AP are you using???
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»magicwisp.com]]> http://www.dslreports.com/forum/remark,13424594 Mon, 16 May 2005 22:42:24 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13383668 wispman : Are you talking about d link or something?]]> http://www.dslreports.com/forum/remark,13383668 Wed, 11 May 2005 15:03:35 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13383448 CapinPete : I'm sure an access point with a built in switch will consume a bit more power, yes. However, it should be a lot less than an access point AND a switch. An access point with a built in switch should not cost much more than just a switch.]]> http://www.dslreports.com/forum/remark,13383448 Wed, 11 May 2005 14:33:09 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13383391 pmurdock : Well, for one an access point with a four port switch built in will draw more power.. and second.. it is less expensive to add a four port switch than replace the whole access point am I wrong?

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13383391 Wed, 11 May 2005 14:26:29 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13382820 CapinPete : Am I missing something? Why cant you replace your access point with another access point that has a 4 port switch built in?]]> http://www.dslreports.com/forum/remark,13382820 Wed, 11 May 2005 13:04:49 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13382684 Semaphore : I agree with NWN & Daggar... I did say it does work..... electronically, and from a network perspective, it's terrible. It won't use any power, but it will likely induce high collisions.]]> http://www.dslreports.com/forum/remark,13382684 Wed, 11 May 2005 12:46:28 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381990 daggardale : I used a simple splitter device like this a few years back. The collision rate was terrible, but it worked. Here's a link to a cheap one, if you're interested.

»www.cablesnmor.com/index.asp?Pag···odID=698]]> http://www.dslreports.com/forum/remark,13381990 Wed, 11 May 2005 10:58:54 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381984 nwn : Looking for trouble here. The ports are not designed for this. They are designed to connect to 1 other device. This may work, if you can get your new device to put the ethernet port into a high-impedance state, so it looks invisible, when not operating. I doubt that it will work, though, unless the other device does the same.
Ethernet works by toggling the voltage from 0 volts to x volts between the transmit pair wires. If one device tries to drive the voltage to 0 and the other is not transmitting, the second device will do its best to maintain the x voltage. The current sourced from device 2 will go way up, E = IR, and to get to 0 volts R will be 0.
This is the reason for hubs, so every device can manage its own transmit pair.
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Scott]]> http://www.dslreports.com/forum/remark,13381984 Wed, 11 May 2005 10:57:46 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381655 cmaenginsb : Well you can try it and tell us how the idea works.

As to current, higher voltage is not higher "pressure" many people tend to make this mistake.

Instead to understand the equations think this way, Watts is a payload of sand. Voltage is the number of dumptrucks you have to carry the sand. Amperage is the number of trips they make.

If the amount of sand stays constant if you increase the number of dumptrucks it will take less trips. The relationship between volts and amps is similiar. Amperage is a function not of things being forced but how much energy the device needs to operate.]]> http://www.dslreports.com/forum/remark,13381655 Wed, 11 May 2005 09:59:57 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381597 pmurdock : Ok.. so what we have is the new device - the battery voltage device will only ever be active for 5 seconds each hour to transmit it's voltage back to the data center.. So in essence I guess the two devices never need to talk to each other. Here is a drawing that I have made to represent the design..

Basically what will happen is a server in the NOC will send out a UDP request to the battery monitor asking for it to send back the voltage every hour. It will only need to respond with a very small packet and then go back to sleep (drawing microamps current - now that is what I call small! :) )

Bear in mind also this is a far-away repeater in the middle of nowhere.. with a very limited potential client base.. I'd be happy with a 1Mbps connection to this location and not worry about saturation..

cheers,
Paul
]]> http://www.dslreports.com/forum/remark,13381597 Wed, 11 May 2005 09:50:12 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381510 Semaphore : If the required layout is that two devices need to talk to one device then a passive Ethernet splitter would work. Yes they make them. I haven't installed one in over a year but they allow two PC's to share a single Ethernet drop. You can't get Full Duplex but you can get 100Mbps. Yes collisions are problem. No the to devices can't talk to each other directly. Ugly but it does "work".]]> http://www.dslreports.com/forum/remark,13381510 Wed, 11 May 2005 09:32:39 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381492 pmurdock : It will be run from a 12V sealed gel cell 285 Amp/hour battery that is charged by some photovoltaic cells.. So the 7.5 v supply is better than the 10V minimum requirement.. however 52 mA versus 300 mA doesn't make sense.. well the equation makes sense.. :)

for 52 mA switch

P = IV

2 watts = (I)*10 volts -> I = 2/10 -> I = 0.2 amps

for ~300 mA switch

P = IV

1.5 watts = (I)*7.5 volts -> I = 1.5/7.5 -> I = 0.2

so it appears that the parvus one is better.. though 200 mA is a horrible draw to have for both of the switches.. :( is that a continuous draw..?

I would think that the draw would be higher at a higher voltage since voltage is like "pressure" if you applying a higher pressure more current would want to flow through the system. So why only draw 52 mA @ 24VDC and draw MORE current (~200 mA) @ 10VDC? This is what I don't see.

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13381492 Wed, 11 May 2005 09:30:23 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381441 John Galt : What is your system voltage?
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A is A]]> http://www.dslreports.com/forum/remark,13381441 Wed, 11 May 2005 09:22:52 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381403 pmurdock : Here's another one I found.. made by Parvus

»www.parvus.com/products/IODataco···itch104/

Says it is a 1.5 Watt, as opposed to the 2 Watt usage by the other one. Though at 5 volts, the P=IV equation says it will draw 300 mA.. how can that be lower than the 52 mA device that draws 2 Watts.?!?

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13381403 Wed, 11 May 2005 09:16:38 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381389 John Galt :
said by pmurdock See Profile:

Does anyone have a feel for what a "low power" switch should be.. is 52 mA really the best we can do?
That's pretty low...!
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A is A]]> http://www.dslreports.com/forum/remark,13381389 Wed, 11 May 2005 09:13:56 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381371 pmurdock : looks like it is 7.5 Watts.. maybe I'm better off going with that ethernet switch up at the top that consumes 2 Watts or 52 mA @ 24VDC.

I see what you mean about tying which wires together.. that does present a problem. As it is now, they are a cross over direct connect.

Does anyone have a feel for what a "low power" switch should be.. is 52 mA really the best we can do?

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13381371 Wed, 11 May 2005 09:09:54 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13381352 Semaphore : The Solar Pop and battery layout please. It's not something we need to do immediately, but it would be beneficial in the future.]]> http://www.dslreports.com/forum/remark,13381352 Wed, 11 May 2005 09:05:40 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13380608 jdmarti1 : My biggest concern would be to create a chance for collisions on my backhaul. That is a very important link. This little unit only takes one watt. I am unsure what voltages you have on your power supply, so you either use the wall wart with this or use the 7.5v.

»www.trendnet.com/products/TE100-S5P.htm
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»magicwisp.com]]> http://www.dslreports.com/forum/remark,13380608 Wed, 11 May 2005 03:31:04 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13380593 wysockib10 : What type of equipment are you using? If you are using 802.11b for your AP you could look into tranzeo wireless they have a radio with two ethernets. ]]> http://www.dslreports.com/forum/remark,13380593 Wed, 11 May 2005 03:23:59 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13380433 cmaenginsb : I don't think you can splice 3 connections together. You can try it though and let us know.

It's not a matter of collision detection, it's how you tie the tx and rx pairs together.]]> http://www.dslreports.com/forum/remark,13380433 Wed, 11 May 2005 02:14:58 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13380380 public :
said by pmurdock See Profile:

I'm not so sure about that.. A hub is useful where you need to repeat the signal over larger distances.

However, the ethernet protocol is a CSMA/CD protocol, which implies "C"ollision "D"etection.. this means that a number of transmitters theorectically could be on the EXACT same wires and still be able to communicate as I understand it. When a collision occurs a random backoff period happens and then the two transmit again at different times.. simply by splicing the wires together indeed I will create the opportunities for collisions to occur, but it still should work? :)

cheers,
Paul
That applies to original thick wire ethernet.
Read up on 10baseT requirements.]]> http://www.dslreports.com/forum/remark,13380380 Wed, 11 May 2005 01:56:30 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13380319 pmurdock : I'm not so sure about that.. A hub is useful where you need to repeat the signal over larger distances.

However, the ethernet protocol is a CSMA/CD protocol, which implies "C"ollision "D"etection.. this means that a number of transmitters theorectically could be on the EXACT same wires and still be able to communicate as I understand it. When a collision occurs a random backoff period happens and then the two transmit again at different times.. simply by splicing the wires together indeed I will create the opportunities for collisions to occur, but it still should work? :)

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13380319 Wed, 11 May 2005 01:40:12 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13379406 public :
said by pmurdock See Profile:

isn't that all I really need though is a way to splice the cables together?

cheers,
Paul
No. Ethernet twisted pair needs a hub.]]> http://www.dslreports.com/forum/remark,13379406 Tue, 10 May 2005 23:07:50 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13379385 pmurdock : isn't that all I really need though is a way to splice the cables together?

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13379385 Tue, 10 May 2005 23:05:39 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13379375 public :
said by pmurdock See Profile:

If I do go with an Ethernet switch what about this one?

»www.controlsysteminnovators.com/itm00045.htm

It shows a power draw of 52 mA with all 5 ports linked up worst case scenario. I will have 3 of those ports so perhaps the current draw will be ~30 mA of constant draw. That's gonna drain the battery BIG time! All just to add a device to allow me to watch the battery because drainage is already an issue!

You need either a hub or a switch. Both draw power. There is no such thing as a passive ethernet splitter.
You can find a lot cheaper one.]]> http://www.dslreports.com/forum/remark,13379375 Tue, 10 May 2005 23:04:45 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13378857 BigCreek :
said by pmurdock See Profile:

»cgi.ebay.com/ws/eBayISAPI.dll?Vi···ame=WDVW
I believe that's just a patch panel. Note the first description line:
quote:
Use in Conjunction with an Active 10/100 Base-T Switching Hub


Here's the manu's page:
»www.hometech.com/techwire/vanco.html
--
SBC Pro Static DSL; Linux. Terrific wife & kids; live on a farm by Big Creek. Software & network consultant.]]> http://www.dslreports.com/forum/remark,13378857 Tue, 10 May 2005 22:02:19 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13378755 pmurdock : I was thinking of something like this..

»cgi.ebay.com/ws/eBayISAPI.dll?Vi···ame=WDVW

and then just wire up the ports to all be the same wires.. should work.. ? :)

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13378755 Tue, 10 May 2005 21:52:28 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13378713 BigCreek :
said by pmurdock See Profile:

I've found a number of ethernet splitters, any suggestions on a good approach or should I just manually wire the connectors together.
Could you post links for some of them so we could see what exactly they are.
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SBC Pro Static DSL; Linux. Terrific wife & kids; live on a farm by Big Creek. Software & network consultant.]]> http://www.dslreports.com/forum/remark,13378713 Tue, 10 May 2005 21:48:56 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13378652 pmurdock : If I do go with an Ethernet switch what about this one?

»www.controlsysteminnovators.com/itm00045.htm

It shows a power draw of 52 mA with all 5 ports linked up worst case scenario. I will have 3 of those ports so perhaps the current draw will be ~30 mA of constant draw. That's gonna drain the battery BIG time! All just to add a device to allow me to watch the battery because drainage is already an issue!

I've found a number of ethernet splitters, any suggestions on a good approach or should I just manually wire the connectors together.

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13378652 Tue, 10 May 2005 21:41:54 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13378505 pmurdock : Basically this is what I have setup. The backhaul radio comes into a PVC box and has a female RJ-45 connector on it - which currently connects directly to 1 access point. I want in essence to "split" off that 1 female port into two female ports - (1) one for the AP, and (2) two for the battery voltage monitor. Don't really think there is a need for a powered hub is there? The cable distances are all less than 10 feet.

the pics - of the solar pop or the battery voltage monitor? :)

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13378505 Tue, 10 May 2005 21:26:05 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13378422 BigCreek : Unless I'm missing something, I don't think a splitter is going to do what you want. They're good for stuffing two Ethernet devices onto one cat5 cable but you still need the ports at the other end.

You need some type of Ethernet hub or switch to connect three devices together.

Perhaps Google for "low power ethernet switch" and see what turns up.
--
SBC Pro Static DSL; Linux. Terrific wife & kids; live on a farm by Big Creek. Software & network consultant.]]> http://www.dslreports.com/forum/remark,13378422 Tue, 10 May 2005 21:15:53 EDT Re: hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13378144 Semaphore : I've used splitters before for customers that were to cheap to install another Ethernet drop, or even a hub. From an electrical isolation point of view I'm sure they suck. But they work... and even a small hub draws a ridiculous amount of power.

BTW... Got pics? I'd love some pointers :-)]]> http://www.dslreports.com/forum/remark,13378144 Tue, 10 May 2005 20:43:17 EDT hub or switch at solar powered POP? http://www.dslreports.com/forum/remark,13377964 pmurdock : I want to add a battery voltage monitoring device to a solar POP that I have, and I will be creating a microcontroller based circuit board with an Ethernet connection on it so I can query the device every hour to see the voltage of the battery and graph it in cacti.

HOWEVER.. ;) my question is - I currently have the access point and the backhaul radio directly plugged into each other. So there are no RJ-45 ports for me to connect this battery monitor to.

Question is : Would a simple 2 port ethernet hub (ie just a splitter and no power usage) work sufficiently or should I put a low power consumption ethernet switch in there. I don't want to add too much of a current load just for the battery monitor. The ethernet physical layer should know how to deal with shared ethernet with automatic backoff and whatnot during a time when the battery monitor and radios want to communicate on the line - I would imagine right? :)

cheers,
Paul]]> http://www.dslreports.com/forum/remark,13377964 Tue, 10 May 2005 20:22:49 EDT