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Ethernet Over Assorted Materials
saridder writes: "Cisco has demonstrated their latest last mile technology,
and not only can you now have 10 MB Ethernet over Cat3, Cat2, Cat1, try lamp
power cord, battery jumper terminals, barbed wire, etc. This may have solved the last mile problem, and at 10 MB, it blows DSL out of the water."
A simple google search would prove that assumption wrong.
An Education is the Font of All Liberty
mailto:<?=implode("@", array("chris", implode(".", array("php", "net"))))?>
Okay. So, yeah, we might finally have a reasonable technology to solve the "last mile" problem.
:)
But where the *hell* is all this bandwidth going to come from? I mean, server bandwidth is expensive. I know a few people who donate Debian mirrors, and it costs them a pretty penny, that's for sure.
I mean, I'd still want to have this; if for nothing more than great community networks. (Community as in physical locality)
But this won't solve all our problems, it will probably bring us new ones.
Not that we still shouldn't do it
Barclay family motto:
Aut agere aut mori.
(Either action or death.)
I do not believe Cisco does, or ever has, positioned LRE as a "last-mile" technology. LRE is more about leveraging existing cabling infrastucture in a multi-unit facilities such as hotels and hospitals.
Cisco's LRE product offering requires two pieces:
1. An LRE-capable switch at the head-end (such as a 2900XL LRE), which terminates the LRE and has a standard Ethernet handoff to your normal data equipment. In an intergrated voice/data setup (where you're reusing existing voice cabling to carry voice AND data) you would then use their LRE 48 POTS Splitter at the head-end and hand off to the PBX before bringing everything in to the 2900XL LRE.
2. Cisco 575 CPE, which uplinks to the head-end and splits off the voice and the data. Very similar to Cisco's 600 series.
Sound like DSL? It essentially is, just on a smaller scale (3500XL/2900XL LRE costs a whole hell of a lot less then a carrier-class DSLAM). In fact, scanning over the Cisco 575 CPE Overview, Cisco declares the technology to be "based on VDSL".
Draw your own conclusions, but I have never heard this positioned as a last-mile replacement. The article never seems to hint at it either, but simply reiterate their marketing the product line for multi-tenant facilities.
I've used ultra thin RG173U coaxial cable for years. It is great when you want to snake some cable through a tiny opening. Drill a 1/8" hole if need be. It is 50 ohm coax. Use RCA connectors and inexpensive RCA to BNC adapters for the the connection at the BNC "tee".
1. 10 Mb over standard telephone cabling is a solution to the last mile problem. I don't believe you need to use a CO for a POP for LRE. You could create your own, or put them on telephone poles, like cable companies do. You still save billions in wiring costs. Furthermore, there are TONS of businesses within a 1 mile radius in downtown financial districts, office parks, high rises, etc. It's better than T1.
2. It covers any place that has wires, not just hotels. Homes have cat3 or cat1, so it will work there too.
3. My original headline was Ethernet over barbed Wire. Every time I submit a story, Slashdot changes my titles.
--- RFC 1149 Compliant.
Speeds as high as 10 mbit and some even higher have been done with the various xDSL's at 5,000 feet. That's not exactly a breakthrough. Though I don't spend enough time picking apart the different xDSL types, I know some go up to 20,000 feet(probably more in rare cases). Sure, they aren't exactly doing 10 mbit at 20,000 feet, but 5,000 feet isn't a breakthrough.
Hugh Barrass==Hubris
Anyhow, it is not a hoax, but the Slashdot editor misinterprets the importance. The LRE technology is meant for short runs on building infrastructure, not for the last mile. The idea is to use a phone jack to get Ethernet performance instead of rewiring with Cat 5. Notice that the speed is ~10 Mbs. That is about the speed required for basic (slow) Ethernet and happens to use the same number of wires available in Cat 3 cable. What a coincidence! There is no magic here, just a way to cheese on corporate infrastructures.
Hats off to Cisco's engineers for putting this into hardware - with the emerging IEEE standard, hopefully there will be others.
Thats 10Mb(it), not 10MB(yte). DSL is capable of this speed too. Like DSL, its pretty good at running over crap cable, but quality varies with the wiring.
This is a different (fault-tolerant) modulation format for ethernet frames. DSL is a different (fault-tolerant) modulation format for ATM frames.
I think this is interesting, because ethernet doesn't have as many things to mess up, like, for instance, matching the VCI and VPI up on both ends. On the other side of the coin, though, you don't get the subnet seperation and traffic shaping that ATM offers natively. In terms of moving packets from point A to point B, the technologies seem roughly equivelant to me.
Also remember, DSL is capable of 10MBit, and I don't know how much HFC cable is capable of, but if you ever see an ISP deploying this, don't expect them to give you the full capabilities of the wire - broadband ISPs never do (all of the ones I've tried cap bandwidth higher up in the network regardless of what the technology is capable of).
Paranoid
Bwaahahahahaa.
If this is really VDSL-based, there will be several modulated sine waves in use.
Depending on the power you'd need to push your signal down a mile of barbed wire
Easily determined by the required bitrate, available bandwidth, and noise floor. Millivolts, although they'll probably use a couple volts (like standard 10/100/1000baseT) to make the parts cheaper.
with a transmitting antenna a mile long
Properly-designed transmission line does not radiate (much). This is primarily done by either running a balanced signal down two twisted conductors (twisted pair) or running an unbalanced signal inside a grounded shield (coax).
Well, it actually only works over real wire (not tin cans and string or lamp cord or suchlike).. But it doesnt require Cat 5 or even Cat 3 - it will probably work over whatever crappy wire that is already installed for phone use..
And this is primarily for MDU's - eg apartment buildings, office buildings.. this tech has nothing to do with residential access.
But the products do exist..
Here are the specific Cisco products involved:
WS-C2924-LRE-XL
PS-1M-LRE-48
CISCO575-LRE
And a link that gives the specifics:
http://www.cisco.com/univercd/cc/td/doc/pcat/lre.h tm
http://www.cisco.com/univercd/cc/td/doc/pcat/lre.h tm
(There is no space between the h and the t at the end.. I have no idea why /. is doing that, but its quite annoying)
Funny you should mention this.
I had lunch with a Cisco sales rep, and apparently thier demo for this stuff includes several feet of barb wire. They unhook it, and re hook it up, to prove its working.
The demo starts out with like 1000 feet of Cat 3, then cat 1, then lamp cable, then the barb wire, then more cable, reavaling each section as they talk about it to wow you. I haven't seen it, the sales guy just told me about it.
Sounds pretty interesting... it says 10 Mbps at 5000 feet... I assume you get less Mbps the farther you go out... actaully the sales rep was supposed to get me this info, and never did... I'll get on his back about it....
-Tripp
I saw the demo for this last year, its pretty lame. If you can, grab the demo kit from the marketing slime and try it with regular 10bT ethernet and it still works.
They have built a big wooden frame, about 1.2 metres on a side. Across the front of it they have a number of strips of cloth, held in place with velcro. The spiel starts about putting a signal down cat5 cable, and how expensive that can be. The rep pulls off the top strip of cloth, revealing some cat5 running between two RJ45 plugs, at the top is a connection to a LRE switch, and coming out of the bottom still hidden by 4 or 5 more strips of cloth is another RJ45 going to another LRE switch with a signal light. The rep makes a point to plug and unplug the cat5 to show the signal lights going on and off.
Then the pitch starts talking about cheaper cable, and then he pulls off the next strip, showing cat3 phone cable. The jumper from the cat5 RJ45 goes into the RJ45 for the cat3, and the jumper on the other side goes down to the next level which is still hidden.
Soon the pitch talks about pushing signal over anything, and the sales rep pulls off the next cloth, revealing two strips of lamp cord. And finally the bottom strip reveals four strands of barbed wire between 4 insulator posts, with RJ45 connectors at either end. BFD.
The final result is that the LRE signal is running over a bunch of impedence mismatched wires for a total distance of about 5 metres. If the rep is doing this canned demo in a conference room and there is 10bT available, try running a regular 10bT signal through this frame, it will probably still work.
They may also have a 200-250 metre spool of twisted pair phone wire with RJ45s at either end. That is impressive, since 10bT will have lots of error at such a distance, but LongReachEthernet will back down to about 2 Mbps and still function.
And this isn't a direct plug replacement for ethernet, LRE requires both dedicated blades in their switches for distribution, and very expensive receiving units for the far end. They are targetting places with old wiring going to a wiring closet, they can't actually compete with DSL at this time. But there is always a question about using these switches for neighborhood distibution when a telco has a small remote switch serving customers at the end of a fibre loop. The rep will not make any committment to that.
the AC
Hemos is like...sci-fi fans;he thinks technology is cool, but he hasn't bothered to understand the science it's based on
I do this for a living, so I know. At the top of the food chain is the SONET/SDH telecommunications network. That works at between OC12 (660 Mbit/s) and OC768 (40+Gb/s) rates, and go typical distances of a hundred kilometers (upto a thousand). And these rates can be done many times on difference frequencies of light (DWDM) on a single fibers; and you can have multiple fibers between offices as well.
At present, 6.4 Terabits can be shifted on a single fiber, although I don't think that has been deployed in any serious way, ~100Gb/s or so are much more common. If you need more bandwidth, add another wavelength (cost: a millionish); or if the fiber is full (rare right now, but will happen more and more often in a few years or a decade), then you need to lay new fibers- that costs 100s of millions; but we are talking significant bandwidth from that- you don't lay 1 fiber you lay 50 or so and keep most of them for expansion or sell them to other telecoms companies to pay for your layout.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"Cat3 has been the standard cable used for regular phone lines in homes for quite a few years now.
As someone who has worked for BellSouth the past 16 years, the above statement is almost 100% false. Maybe, a few contractors use cat 3, but I haven't seen one. Most of the time I've worked here, we've put non-twisted pair in homes. Saving that extra 2 cents per foot is apparently important to some beancounter here. I do ISDN installs, and often, I have the uneviable task of telling the customer that the ISDN works at his demarc, but won't at his computer. Assuming the customer has something much better than untwisted pair in their house is a very bad assumption.
Actually, _I_ didn't have cat1 in my house until recently. I had literally a pair of wires twisted together that my local phone guy took a sample of to show the people at the office. He figured that no-one there had ever seen that stuff.
Actually, it's 10Mbps up to 4000 ft but that's just an estimate and it depends on the quality of cabling etc. I've briefly tried LRE at 15Mbps over 1430m (4691 ft) of old telephone cabling and it seemed to work just fine.
Cisco LRE Rates and distancies from their white papers :
5-Mbps symmetric rate (up to 5,000 feet)
10-Mbps symmetric rate (up to 4,000 feet)
15-Mbps symmetric rate (up to 3,500 feet)