Does having multiple RJ45 jacks degrade the Internet signal a lot?

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Exactly. :-)
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wrote:

Something just dawned on me and I apologize that I didn't recognize it much earlier.
When you talked about disabling the 4200's router and how it then forwarded all ports to a single IP, I should have recognized the situation and complained right away. I think we agree that disabling the router section essentially turns the 4200 into a DSL-Ethernet bridge. Bridges operate at Layer 2 and have absolutely no concept of ports. Therefore, they can't do any port forwarding.
Port forwarding refers to rewriting the destination IP when the destination port matches a certain value, and bridges don't rewrite destination IP's. Your description of port forwarding led me to believe that the router section was still active, since only the router can do port forwarding, but I see now that you were talking about standard bridge behavior and not port forwarding at all. The use of "port forwarding" when port forwarding wasn't involved was unfortunate.
You also mentioned that, with the 4200's router section disabled, you can only plug in one computer, and you made it seem like a limitation, saying additional computers wouldn't work. Again, though, that's standard bridge behavior. Your DSL ISP probably only allows you one IP address. If you need more, you need a router. (You also tangled up the port forwarding stuff into that mess, but it has no place there.)
Next, you mentioned that the 4200 can only do NAT to one device with the router section disabled. Again, that's not quite right. Bridges don't do NAT. (Bridges operate at L2 and have no concept of IP addresses.) What you should see is the single IP address allocation allowed by your ISP. There's no NAT involved unless the router section is active.
This clears up just about everything for me. Let me know if you have any questions or clarifications.
I'm avoiding the VPN stuff. I'll test it myself someday, just to satisfy my curiosity.
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Not exactly a conflict, but a simple routing problem. Let's say your modem's LAN interface is 192.168.1.254 (/24), as you suggested above. Now you connect a router to the modem's LAN interface, and you configure the router's LAN interface to be 192.168.1.1 (/24). Both devices are using the 192.168.1.x/24 subnet.
Given that scenario, there are no addressing conflicts, but you won't be able to reach the LAN interface of the modem because there's a router between you and the modem. You fire off a packet to 192.168.1.254 and your PC's network stack checks its netmask, determines that the target IP address is within that netmask, so it uses ARP to translate the IP address to a MAC address. Well, it doesn't get a reply since ARP doesn't pass through a router. Ergo, no communication from the PC to the modem. The fix, as you stumbled upon, is to use a different subnet (or at least a more restrictive subnet mask).
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On Mon, 26 Dec 2011 22:38:06 -0600, Char Jackson wrote:

I wonder what would explain how I can connect to the broadband router's web page (eg 192.168.1.1) and to the radio on top of the antenna (eg 10.100.0.1) from the same wireless laptop inside the house.
I can connect to both - but since the laptop is 192.168.1.(something), by all rights, it should only connect to the broadband router (which is on the same subnet).
How it still can connect to the antenna radio (which is on a wholly different subnet) is beyond my understanding.
BTW, here's a daylight picture of the antenna wiring.
What do you guys do to secure wires when you go down an antenna?

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On Fri, 30 Dec 2011 09:03:27 +0000 (UTC), Chuck Banshee

I assume you're able to connect to the WISP radio via your broadband router. That's what routers do, they act as an interface between two or more networks.

That doesn't look quite as good as I'd hoped. Just thinking out loud, I wonder if you'd get more stability, more protection from the elements, and more protection from general damage by putting the vertical run inside a small conduit, and solidly attaching the conduit to the pole.
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On Fri, 30 Dec 2011 11:26:57 -0600, Char Jackson wrote:

When I look back at it, it 'does' look a little shoddy just wrapped around the pole like a barber-shop twist.

That's a GREAT IDEA!
I could also, I guess, put the wire INSIDE the water pipe mast but I like the idea of strapping PVC conduit to the pole, alongside the pole, with the wire running down.
PS: I wish I thought of that 'before' I did it - but this suggestion will help others and I can do it in my retrofit when I add the TV antenna!
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On Fri, 30 Dec 2011 21:23:31 +0000 (UTC), Chuck Banshee

Hopefully, someone who's done it will weigh in before it's officially declared a good idea. I suppose you'd cap the top of the conduit to keep most of the water and some of the critters out, or use two 90 degree fittings so that the Ethernet cable enters the conduit going up, over, and then down the length of the pole. Or something like that.
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wrote:

Argh. I've never seen it done by running the cables through the mast, even with a tilt up mast derrangement. <http://www.floatograph.com/rmmast/ <http://www.solarwheel.co.uk/tilt-up.php <http://members.westnet.com.au/page3/tilt_over_tower.htm <
http://www.photomast.ca/Bulletin_Board/Trailer.jpg
Drivel: This isn't a tilt over mast, but is kinda cool for keeping the antennas from digging a hole in the ground when lowered. <http://nn4zz.com/tiltplate.htm
However, running coax up the center of a monopole for cellular service is standard procedure. The differnce is that the monopole is MUCH larger than the suggested water pipe mast. This offers easier access, additional support points, and less of a mess. Monopoles do have their problems, as these links illustrate: <http://802.11junk.com/jeffl/SCCARC-talk-2010-06-18/Burning-Towers.htm
The problems with running wires down the center of a mast are not very obvious: 1. The top of the mast looked like a coax "fountain" with all the cables dripping out of the top in all directions. It was truely ugly. 2. There is no way to secure the cables except at the top of the mast. The entire weight of the coax is supported only at the top. I would have expected the cables to stretch slightly. Instead, the sharp turn made by the coax cables going out the top caused the center conductor to cold flow through the dielectric, eventually shorting the cable. 3. If the mast is tilt over, as is quite common, the cable out the bottom has to include a rather lenthy service loop. If you're going to secure it short pipe stub, you run the risk of cutting the cable if you lower the mast to the ground.
Bottom line: Lousy idea.
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# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
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wrote:

<snip> We were talking about a vertical conduit, not the mast.

Single Ethernet cable in this case. When taken in context with the looks of the concrete base and the overall appearance of a water pipe mast, the level of beauty is not out of line.

Yes, there are ways to secure the cable but they haven't been discussed.

I haven't heard of any plans to tilt this mast.

You're probably right, even though each of your objections doesn't actually apply in this case.
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Photomast looks real Rube Goldberg. Just how expensive is a news van with telescoping mast?
In the photomast wmv file, it looks like they get it tilted up just in time before a car go barreling by.
My recollection is there are military antennas where the mast is the coax, so to speak. That is, support and RF feed are one item.
In any outdoor design, there is the school of "weep hole", and the school of watertight. Some people claim sealed units really aren't sealed, so whatever water does get in will eventually do damage. Hence they come up with a weep hole. The other school of thought is to seal everything up like a drum.
I bought an old NEMA box, which in theory is sealed, but noticed they stuffed it with desiccant packs.
Back to CAT5, I notice Moto Canopy setups leave the data cable exposed.
Come to think of it, I've seen some satellite hookups where the coax is in the LNB(F) support arm.
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wrote:

Marine boxes are sealed and do a good job. We'd add a block of camphor before we closed them up and over near 40 years of working off shore never had a box leak (save ones that were mechanically damaged)
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On 1/3/2012 12:49 AM, NotMe wrote:

I suspect Jeff is closer to reality, though I don't doubt your boxes didn't leak. For electronics, just moisture in the air is enough. You would probably need a nitrogen purge and pressurization scheme for electronics. Some camera housings work that way.
Camphor fumes are to reduce rust. I don't know the chemistry behind this, so I don't know how effective this scheme is for electronics.
A weep hole doesn't keep out salt.
Fry's has the satellite F connectors. I'm not really impressed with the satellite coax they sell, though I use their patch cables for temporary setups.
Quad shielded coax has been at buzzword status for a while. Almost like drop forged. [Yeah, we dropped that wrench before shipping it to Harbor Freight.] Yeah, there are four shields. Not the greatest shields.....
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Not nitrogen. Too expensive. Just dry air will work.
In a past life, I designed marine radios for Intech Inc. We learned quite a bit about water proofing. Much of it was learned the hard way. Most of my radios would work after the boards were soaked with a bucket of water. There's no magic there, just use low impedances for literally everything and fairly wide trace spacing. However, I had to also deal with vendor supplied SCADA hardware, which was full of dense PCB layout, high impedances, RF sensitive design, and other nightmares. Kinda like what you find in the typical consumer grade wireless router. The decision was made to not modify the design, but rather to protect the sensitive SCADA boards. I won't go into all the things that didn't work, but I will say that the only thing that worked every time was a pressurized box, vertically mounted boards (so that they drain) and dry air. To prevent condensation in case the dry air went away, there was a small heater to keep the temperature above the dew point. My idea of dry air was a bicycle pump with an air compressor dryer filter attached. Add a gauge, a desiccant cartridge, and the usual warning labels. If you think you can do better with other technology, you're welcome to try.

Dunno. Most of my stuff was aluminum. There are products that you can insert inside aluminum tubing (such as for hang gliders and antennas) that prevent internal corrosion. I don't know the chemistry offhand.

Actually, a weep hole has its place. If you can't pressurize with dry air, then you have to find a place for the water to escape. Water will eventually evaporate in temperate climates making a weep hole functional. However, puddling is very bad. That's why I mound the boards vertically (so they drain).
The absolute worst idea is somewhat sealed box, that's not pressurized. It works like a water pump. Water collects on the box seams. The sun comes up, heats up the box, causing some of the inside air to leak out. The sun goes down, the box cools off, and a partial vacuum is created inside the box. This sucks the water sitting on the seams into the box. The next day, the process is repeated. Eventually, there's quite a bit of water inside the box. It doesn't just sit on the bottom of the box. It evaporates when warm and condenses on the electronics. It's MUCH better if the water drain out the bottom after every cycle instead of being trapped inside.

I make my own CATV cables. The compression type of F connector is quite waterproof. I've also used it at 2.4Ghz. Works fine. You'll never notice the 50/75 ohm mismatch as the reflections are all lost in the high cable losses. <http://www.qsl.net/n9zia/wireless/75_ohm_hardline.html

Quad shielded exists only because the FCC demanded that CATV leakage be very very very very low. The only thing that does that is quad shielded. If you have an ingress problem, use quad. Otherwise, double shielded (foil + braid) works just fine. My most irritating problem with RG6a/u is the unplated copper center conductor. It like to corrode, especially when the mating connector has tin plated contacts. I've been experimenting with electroless silver plating the copper, which seems to help.
Archived notes on corrosion by a real expert (not me). <http://yarchive.net/electr/galvanic_corrosion.html Worth reading methinks.
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Jeff Liebermann snipped-for-privacy@cruzio.com
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I suspect the old Beldin foil plus braid is better than made in China quad-shield. Yes, quad is more about leakage than "infiltration".
I didn't want to go into this because it gets complicated, but I buy dry air from scuba shops. You need your own tank. Air is cheap. Inspections are not. Tank, hose, regulator and the nozzle set me back $50. When I blow the dust of out something, I don't hit it with refrigerant, which is what canned air does.
The tax laws regarding buying compressed air are interesting in a bizarre way, not that it makes much of a difference in price. If they compress the air at the shop, that is a service, and it has one tax rule. If they get a big tank of compressed air and use it to fill your tank, it is stored inventory, and the tax rule is different.
I have no idea what it takes to keep nitrogen at home. I'd have to research where to buy it. The only nitrogen I ever used was bought by some corporation and it was the mad scientist liquid type. All that said, since nitrogen isn't being used in life support like scuba air, I think it would be relatively cheap.
NEMA with desiccant inside is used a lot, so some people think sealed is fine. I have no surveys to back this up, just personal observation with a very limited sample.
On some GPSs, the weep hole is visible. It has a membrane valve. A friend got this brilliant idea to seal up the weep hole. He took a trip in an airplane with the GPS and the keys got sucked down due to the pressure change. Sometimes when I go camping, I can't open the ammo cases because the pressure change has sucked them down. So yeah, sealed isn't all that good in some situations.
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Ok, you opened this can of worms. What you want is *DRY* nitrogen. The stuff the dive shop sells is good enough. (I used to dive but gave it up after all my stuff got ripped off). Basically, truly dry nitrogen has to come from a cryogenic tank, which is expensive. The measure if dryness is the dew point, or the water content in ppm. Look for something like -70F N2 dew point or <10ppm.
A somewhat less critical source is the local drag racing tire supplier. For some magic reason, they like to fill the tires with dry nitrogen. The local Costco also does that.
Oh, if you're wondering why it has to be dry, think of the inside of the pressurized box in terms of acid rain.
However, all this is overkill. What you want is any minimally reactive gas that's dry. You could use CO2 if you could find a suitable dryer. For pressurizing outdoor boxes, you only need 2-5 psi differential pressure. Any more and you'll blow out the seals. I learned that by pressurizing a radio to about 40 psi which caused the plastic front panel, keyboard, and display to fragment and spray shards all over the lab. Therefore, all you need is a bicycle pump and a dryer from an air compressor. You won't get -70F dew point, but it will be good enough.
Incidentally, the sloppy way to test if you're doing it right is to put the radio in the freezer for at least 24 hrs. If you then open the case, and find frost and snow on everything inside, you have a problem.

No kidding. I have several steel tanks that are ummm.... 10 years out of date and need a hydro test. One spewed some rust when I bled it down. The local gas house wants to give a fabulous $10/ea for them.

I have several air compressors. Well, not counting two that are out on semi-permanent loan, I have 4 air compressors. They're easy to rebuild. However, for when I was blowing out my dive stuff, I used a Gast oil less air brush compressor. It doesn't generate much volume or pressure, but it also doesn't spray oil into the mouth piece.

Yep. Desiccant will dry the air for a while. However, if you're pumping water into the case by alternately heating and cooling the case, it won't last very long. Desiccant works best on pressurized systems.
Incidentally, I still pressurize Heliax coax runs (when possible and except for the local ham repeaters). I recently discovered that one of my original installs was still pressurized after 20 years of neglect. When disassembled, there was no green slime and everything was shiny and new looking.

Chuckle.
Install a one way check valve? I use a bicycle valve or plumbing air bleed valve fitting for filling. It could also be used to equalize the pressure before opening.
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I can see the desiccant being an issue if you don't service the box and change it out. I wonder if they are depending on the heat from the box to keep things dry inside.
I have a downconverters handy. [Learn by destruction stuff from ebay. ;-)] They just use a sealed case. Both have a black fuzzy thing inside, purpose unknown. I don't think it is a desiccant.
Pelican and similar cases have check valves. I just curse and yank really hard and the ammo cases open. It is is impressive on some of the cans with good seals.
I can't believe what they get for ammo cases these days. You would think with a decade of war we would be awash with cases. I was driving around Palmdale, spotted an Army surplus store, and decided to check it out. Small ammo boxes I got for $5 at the flea market were $30. I've bought real transit cases for that kind of money.
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I don't think so. The box won't get hot enough to do anything useful. I think you have to get the desiccant rather hot before it will release the trapped water.

The black fuzzy stuff is a carbon microwave absorbing sheet, intended to absorb RF. The idea is to absorb rather than reflect as in a metal shield.

Locally, we have: <http://www.surplusinc.com They don't even list ammo boxes on their web page. They have a few and yes, they're seriously overpriced. When Ft Ord closed, their supply of goodies dried up. I'm not sure why, but I'm seeing zero military surplus coming back from Iraq and Afghanistan.
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On 1/5/2012 9:16 AM, Jeff Liebermann wrote:

of a bluetooth dongle. If I get motivated I'll open one up again and send a photo.
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wrote:

From your description, they're simply placing the LAN IP in the DMZ, to use common Linksys parlance. No surprise, and no big deal. It's good to see that they do that by default, rather than making the customer jump through port forwarding hoops.

Long before you have a problem with forwarding ports to multiple computers, you have a much bigger problem: there's only one IP address available on the LAN side of the modem, right? So multiple computers don't work because only one of them can acquire an IP address, not because of any port forwarding limitations. As you said, attaching a router as the first device allows multiple computers to then be attached, and port forwarding is then managed within that router. The limitation remains that a given port can only be forwarded to one computer at a time, of course, but at least it's no longer all or nothing.

I wasn't able to parse that paragraph. How is 192.168.1.1 traffic finding its way to the WAN side of the modem? How did it get there? It didn't come from the Internet, since it's not routable, and it didn't come from the direction of the LAN, since there's a device (the router) in that direction that has that address, so where did it come from, the ISP?
Further, if you plug 192.168.1.1 into a web browser and you have a device on your LAN with that address, you'll access that device, (even if that device is a router). If the router is forwarding traffic addressed to itself to its WAN interface, well, it's broken. Replace the router.

Ok, this part relates to a discussion we had recently. Thanks.
Thanks for the warning, but it didn't turn out to be very messy at all. I appreciate the details.
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wrote:

Nope. Look again. The DMZ is usually defined by the router and is only concerned with incoming traffic, not outgoing. In this case, the redirection is happening in the DSL modem, not the router. The router duitifully passes traffic destined to the modem out the WAN port. The DSL modem traps outgoing traffic destined to its management IP address, and redirects it to the internal web server, and not out to the internet. That's quite different from the (misnamed) DMZ feature found in many routers. What makes it a big deal is that it probably breaks a few RFC's, is totally undocumented, and a rather good idea.
More later.... I'm late for a paying appointment.
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