Odd Network Issue

PoE needs a DC path. We have a partially Ali telephone line, Ali is very prone to breaking in the IDC jelly beans. When that happens the insulation/jelly holds the wire in place so the AC ADSL signal can just about get across but there is no DC path so the phone is dead.

Time Domain Multiplexer? Time Domain Reflectometer (TDR) surely?

--
Cheers 
Dave.

The PI, especially with a marginal power, will have more of an issue with cable length than other devices.

You can generally go close to 200 meters with modern cat6 cabling and standard 100mbit cabling. That is actual cable length plus

6 meters for every connection. If you use drop cables in each end that is 4 such connections, making for 24 meters off right there.

Also, the DHCP client code in debian is a LOT more conservative than similar stuff e.g. on windows. With the combination of the right (wrong) router/dhcp server this may lead to some ip address issues.

I noticed a huge diffeence at home when I moved my dhcp server from the telco supplied access box to a BSD box using isc dhcp.

What make of dhcp server do you have?

-- mrr

In message , Morten Reistad writes

The dhcp server is part of my Thomson router.

The link is cable from router to switch, cable from switch to wall socket, cable from wall socket to Pi.

Adrian

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Nasty cheap things supplied by the ISP, because they are cheap and nasty. Have a look at an ASUS router, vastly better firmare, stonkingly faster WiFi.

As people have said, probably too much for the Pi's little chip to drive. To eliminate that as a factor, try putting a small 100Mb switch at the end of the cable, and plug the Pi in to that.

---druck

.254 is what BT Home Hubs use - I haven't had a problem with mine.

--
Mike Fleming

.254 is neither unusual nor has it any problems.

Nor incidentally, is the Ethernet chip in a Pi in anyway different from the Ethernet chip in anything else in terms of 'driving a long cable'.

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The Ethernet chip is a fairly standard usb-to-ethernet one. The PHY (the line drivers) are different. And they are somewhat power-constrained.

I haven't got firm experience with the pi on this, but on similar low-end ethernet I have experienced that you have to take the

100 meters limit (less 6 for every connection) quite seriously, whereas laptops/desktops etc easily connect just fine on links that are up to twice as long. 3com even have 10mb eternet drivers for 600 meter cat5 runs of cable, and I have used them to build networks some times.

-- mrr

Boost the Pi power or abandon the Ethernet cable and go WiFi. You know what doesn't work, so eliminate that and replace it with something that works. You appear to be trying to justify saving your Ethernet cable run, which you continue saying doesn't work with the Pi reliably.

You don't have an odd network issue, Adrian; what you have is an under-volt brownout problem which MANIFESTS itself as an intermittent network issue - the low voltage unable to adequately drive it's Ethernet segment.

Why do power companies transmit and distribute electricity on high voltage AC? Because otherwize house current DC plants would be required every five kilometers due to the overwhelming resistance in copper. By shifting the High Amps to lower Amps/higher Voltage and letting the electrons dance in little circles atop waves in the long distance transmission lines then those same electrons don't have to punch holes through miles of resistive copper, heating them up. There is still loss, but much less than resistively warming a hundred miles of copper with 220V direct current.

Why do model railroaders wire their track at several points, three or four in an oval? Because the current resistance of low voltage DC through the just the tracks (while warming them) is too great at the back of the oval, warming the track instead which causes the model locomotive to slow down to the resisted and now lower voltage at the point of pickup.

So finally! You have written the key to your own quandary - a very long run of DC behind a (probably metal) rain-gutter powers your Pi. How many meters is that run? Have any critters tasted the power cable? That would expose the bare wire to corrosion and increase resistance there in turn and time. Are you stringing the Ethernet Cat5 alongside the unshielded power? Aha! You have described poor engineering indeed. Run the power and data separated, a foot apart or more if parallel, but best at right angles. Don't loop either, make U bends for strain relief. To test that brown-out under-volt is the problem try this; run an extension cord of house mains out to the Pi in the garden. Connect a known good power wart USB charging adapter at the garden end to the Pi. I'll bet your networking issue vanishes by giving the Pi Ethernet enough juice to signal your router over Ethernet. A long run of stranded DC power then siphoned by the Pi to operate the processor and other chips and then modified as lower voltage Ethernet signal to be reflected back to the house on a long run of stranded DC digital signal in the resistant Ethernet cable just won't have enough voltage to trip your router buffers consistently to recognize data signal causing the IP drop when the router polls the Pi, unable to clearly hear the response "I'm still here."

Gee, I'll bet you are running unshielded power alongside your Cat5 in the eaves behind that (probably metal) gutter. That's almost as bad as looping the extra lengths of either or both in a coil, that's called the primary half of an air core transformer - inducing current into nearby lines, and picking up plenty of noise. Have you tried wireless? A USB WiFi dongle price can be under ten ?10. That may solve your wired Ethernet but not your Pi under-volt.

So, o.k. and functional we realize it's not a good idea to run house-mains outdoors for anything more than temporarily without protection such as a dedicated conduit built to code. Perhaps another approach is ordered. Replace the long 2A 5V run with a wall wart of 5A at 12V, buy enough exterior 12Vcable to reach, and just at the Pi end adapt/convert a cigarette lighter socket car charger for the final step down. I got that idea from my dad, a retired electrical engineer who wanted a 'round-the-clock USB charging station at a picnic table in his garden. He had purchased a Solar Umbrella with 4 USB sockets which charge while talking on his mobile, which at first satisfied the requirements, but being a retired electrical engineer who now has a toy to tinker with, he did what retired electrical engineers with new toys to tinker with do. The first mod was to wire the data lines together making the umbrella charger a hub as well. The next modification was to solder in some diodes to a 12V 5A USB car charger cutting off the cig-socket plug of the car charger which instead now hacks to a connector at the base which accepts the female plug for his trenched 12V garden lighting system. The diodes prevent the solar umbrella from powering the garden lights and there's a self-resetting 12V breaker from a junked car in there as well. Now when the sun goes down, an electric eye at the wall box switches on the garden lighting with plenty of current to keep the table hub working well as a charger, He says when he gets around to it, he'll connect the data to the rest of the house USB distribution first ("Easy, trench this old phone cord." he says. (which means in a separate trench across but not next to the lighting, and updating the utilities map)) then Velcro some rechargeable batteries under the table top and wire them up as an uninterruptible five volt supply. He's done the construction so far with this future plan in mind; eventually powering the garden path lights (but not the other tree/bush/wall lights) when he upgrades them from halogen to LED. The umbrella powered hub is juicy enough to run simultaneously my MagicJack, an optical mouse, a pocket printer and my terabyte buffalo external USB harddrive and still charge his mobile while talking/surfing/file transfers. Too bad my laptop input requires 5A 19V or I'd try that hookup too. Now you've got me curious. The next time I visit my pop, I think I'll pack a Pi and an extra unpowered hub and give it a go in the garden with a wired mouse and keyboard, oh, problem - no HDMI display there. Well, it runs WiFi and Bluetooth each dongle in a USB socket already, and rarely anymore do I flip on that display anyway. Most of the time it's headless anyhow, running Xming client and server over the laptop PuTTY for queries and display. That low power Pi-B+ has replaced my 450Watt/Hour sucking dedicated desktop tower for serving in-house intranet pages, mp3 files and a household inventory (shopping list) Wiki. "Don't stand there gawking with the 'fridge door open! You know what's in there - check the Wiki! (and remember to markdown what you knicked.)" "You know I don't like mustard and you have twelve kinds in the door." Confidentially, I don't like mustard either.

== Go Solar Power == Here in the States, the 99.9 Cent Only store and Dollar Tree have both stocked solar garden path LED lamp stakes. I've purchased a dozen for later hacking because each came with a white LED, a single pole double throw switch, a crude regulator/daylight sensing charger chip, a rechargeable six Volt NiCad battery. (same as my desktop computer, that the electronics store wants $16 for, and the cash register folks wants $32 for.) And, of course, the .5cm2 solar array to cap it off. I considered kit-bashing some in parallel to power a garden Pi 'round the clock, I figured out six would be sufficient to run a Pi all day and collect enough charge to run it at night, given 3 days in a row of rain before undervolt. Again that Pi I/O would be WiFi dongle and Bluetooth Dongle equipped, but headless and without keyboard or mouse, (but it could use them with the Bluetooth when needed,) configured as a public share of music while running an FM radio antenna on GPIO 3 fed with repeating all of the .mp3s in the broadcast folder continuously in alphabetical order (sorry no live MagicMicrophone capability.) That's as far as I can help because that's a possible project I've not yet built. You may now want to inquire if there are others who solar power their Pi.

You could go solar on the cheap, juicy enough to broadcast WiFi and FM or enough perhaps to drive the copper data back to your router, I'm just sayin'.

"Adrian" wrote in message news:9j$ snipped-for-privacy@ku.gro.lloiff...

plugged

net.

the

I

else's.

MAC

a

out

much

netbook,

That's because the Netbook provides sufficient current on the data lines of your Ethernet to secure and maintain an IP address. I'll bet your Ethernet cable is of unshielded stranded wire as well. Ohms my... and yet you still resist the solution energetically.--(o=8>wiz

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On Mon, 8 Jun 2015 16:38:11 -0700, "DisneyWizard the Fantasmic!" declaimed the following:

The traditional reason was for BLOCK CONTROL... One could have a locomotive in each block, and via switches (not turnouts), define which speed control was connected to which block.

These days, they likely feed full voltage to the rails, overlay an RF control signal, and use a micro-process controlled ESC in the locomotive to vary the speed in response to the RF commands.

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four in an oval?

tracks (while warming them) is too great at the back of the oval, warming the track instead which causes the model locomotive to slow down to the resisted and now lower voltage at the point of pickup.

which

locomotive to

True that Wulfraed, I did have a qualifier which didn't make the final edit:

The example stated was one attempt of two to explain without math that resistance increases linearly with conductor length. Nowadays I spend much more time around 1/8 scale Live Steam operation, besides, the greatest R-Pi audience may be most familiar with the HO gift set as a toy train 'round the tree at Christmas and probably never picked up a copy of Model Railroader, much less a book on control and signaling. I did consider the special case of those familiar with modern digitized speed control, and you and I are certainly special case, on the fringe of the undervolt Pi problem. Now to bring it back on topic, how about speaking up about signaling and control of model railroads powered by Raspberry Pi?! In the Venn diagram of the Universe of Disney, I could tell you more than you ever wanted to know about the intersection of Trains and Walt Disney. Come visit and pick my brains -->

for a schedule, map and more information about the only FREE Disney Theme Park in the world.

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In message , DisneyWizard the Fantasmic! writes

The DC section of the power lead is about a metre long (pretty much a standard type of supply), and it is the same power supply that I was using in the house, where it was working fine. The guttering is all plastic (and the power supply crosses it at a right angle), and no critters have nibbled the power supply.

Adrian

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