Network Testbed Emulab.net

gseidman writes: "Have you ever needed to simulate a network? Tired of old ns? Do you just hate dealing with hardware in general? Take a peek at Utah's Emulab.Net. They have over 300 PCs, some StrongARM devices, roughly 5 miles of cabling, a huge and expensive switch, and great software for setting up a virtual LAN. They also have a gallery showing the machine room in various stages of completion (did I mention five miles of cabling?)."

Comments

Simulation is never perfect

[euroderf]

This is the difference between book learning and experience. Sure, you can 'test' a network under idealised simulated conditions, as one might 'test' a plane in a wind tunnel, but till the network is reality, and the secretary spills a cup of coffee on the router or the chief engineer urinates drunkenly on the packet switcher, you can't tell how your network will perform.

What is it with the modern generation who think that simulations will improve their likely performance? It is all idiocy, when I was young we did things with a spanner and looked at das blinkenlights under real world conditions. This is so much nonsense, really, the sort of thing I'd expect to come out of our modern CS courses.

Computing is just an offshoot of down-and-dirty engineering, and none of us should forget it. The day we forget the feel of the netowrk cards in our hands, the smell of the overheating cat5, is the day we lose control over the netowkrks of America, the day that our economy starts going backwards.

Re:This is very cool.

[fnordboy]

Basic research is fine, but I wish that the money poured into it would go towards immediate business applications.

Now that's just silly. Basic research is incredibly important, and it is vital to the economic health of the country (and the world, for that matter) that money is spent on it. Where did the transistors that your nice new Intel chip is made up of come from? Basic research. How about lots of medical technology like MRI machines and x-rays? Basic research. And there are lots of indirect benefits to basic research as well. How about those snazzy digital cameras? The need for high-quality CCDs for astronomy (*cough* hubble *cough*) and for other research applications pushes that. Do you like the world wide web? Thank a bunch of physicists who put it together so they could share their data.

The point of basic research isn't the small, immediate payoff - it's the hope that somewhere along the line, some scientist is going to come up with something that will revolutionize the world - just like the transistor! So I respectfully disagree with you - while it's important for companies to be concerned with their quarterly earnings reports, in the long term, basic research is most certainly worth the investment.

Re:spamming us /. ??

[Atilla]

Have You Ever Heard of Sarcasm?

Re:5 Miles of sloppy cabling...

[monkeydo]

Not only that, but they have 7 slots worth of 48 port 100Mb cards (33.6Gb) and 1 Gb uplink. That might be a little of a bottleneck if more than a few of the nodes are trying to pass upstream traffic.

Just a bit surprised ?

[pruneau]

Those guys just bought those 4 huge 6509C Cisco switches for big bucks.

I assume that One is acting as the main router, and the other are using it. I assume also that the switches are interconnected with 2x1Gb/s fibers, probably full-duplex and load/sharing above the two links.

What surprises me is that those switch fabric supports up to 256Gb/s bandwidth, but they are just connected with 2Gb/s links : talk about some bottlnecks here...

But maybe I did not read enough documents ?

Any comments from the builders of that lab ?

Re:5 Miles of sloppy cabling...

[mac.newbold]

1) It increases the number of wires by 4 per 48. It however lessens the trouble involved if a module fails - apparently you've never had the joy of unplugging, keeping track of, and re-plugging in 48 Cat-5 cables in a hurry. It's not fun. An increase of time in the beginning far outweighs the risks of the increase of time in an outage. I can show you pictures of rats nests and tell you horror stories all day about this.

It increases the number of wires by 8 per 48 (see below), and yes, we've had module failures before, and I have moved 48 cat-5 cables in a hurry. These module failures are so rare that its not even worth the extra time at the beginning to try and make it easier.

2) The standard Cat-5e configuration still only uses 4 wires. The Telco panels are wired as such. For each Telco harmonica you get 12 ports - quite dense enough.

It uses 4 wires when running at 100Mbit, but like I mentioned before, when we go to gigabit over these cat5e cables, we'll need all 8, since the gigabit over copper products we're looking at use all 8 wires in the cable.

3) There's nothing that says that gig won't be supported over telco, just like there's still no set-in-stone standard for gig over cat-5. Nothing even says that cat-5e is going to be required.

Every product on the market that I've seen requires cat5e for its higher standards, and I've never seen a patch panel/telco combination that claims to be able to support the high requirements of gigabit over copper.

Now maybe you would have done it differently, and that's fine. Our needs are different from yours, and our criteria for judgement of our options are probably quite different as well. What we chose to do has worked out very well for us, and we're very happy with the way that things are set up. If you're still not satisfied, perhaps we should just agree to disagree....

Mac