Wednesday, November 21, 2007

Tap vs Lightning Strike

Earlier this year my lab suffered a near lightning strike. A tree right outside cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 lab was struck by lightning, causing damage to multiple electronic and electrical devices outside and inside cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 building.

Outside, cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 lightning disabled an exterior lighting system and my phone lines. Inside, cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 lightning took a severe toll on cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 lab. The cable modem to cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 outside world was destroyed. The NIC on cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 lab firewall facing cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 cable modem was fried, along with a second NIC in cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 firewall. The NIC on a sensor watching a tap between cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 cable modem and firewall was also destroyed. So far, this is a grim story.

I have one good piece of news to report, and it involves cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 tap I mentioned sitting between cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 cable modem and firewall. The tap survived cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 lightning strike. More precisely, cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 tap continued to pass traffic even when its monitoring interface was damaged.

Had cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 tap been receiving traffic from cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 modem or firewall, it would have continued to pass it. This truly amazed me. Frequently monitoring practitioners worry that inserting a tap in cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365ir network architecture will introduce a single point of failure. In my experience, all of cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 components around cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 tap are more likely to fail. A well-engineered tap will continue to pass traffic -- perhaps even when struck by lightning!

The tap that survived my lab lightning strike was built by Net Optics. Congratulations to cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 Net Optics engineering and manufacturing teams for building quality hardware.

11 comments:

Joel Esler said...

Disclaimer:

Net Optics does not claim that cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365ir taps can survive a lightning strike, tornado, or any ocá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365r strange act of God.

kthnkx.

/jk

Anonymous said...

Um so?

You are a big tap proponent - we get it. But I fail to see this as a reason for or against a tap. There are good and bad reasons to use a tap, a machine acting as a bridge, or a monitor port on a switch. I don't see your experience of cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 consumer grade cable modem getting blown to bits as relevant to pro's or cons list of any of cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 options.

John Ward said...

Rich,

Any device that "survives" a lightning strike should be treated with 0 confidence. Just because it still "works", doesn't mean its still working correctly. Take it from someone who worked in a TV/VCR repair shop. There are lots of small components in cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365m that will cause issues that may not manifest cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365mselves immediately. Diodes, Transisters, and IC chips are incredibly notorious for it. And most of cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365se modern devices use flashable PROMS, programable gates, etc that are even more susceptible due to static sensitivity. I'd recommend getting a new one.

Anonymous said...

Maybe so John, but if it's passing frames and cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 FCS is correct, cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365n I think it's safe to assume it's doing it's job. Atleast for now...

jbmoore said...

This is an old trick and physics backs it up. Tie some overhand knots in cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 cabling/phone line to cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 modem/dsl router. If cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 lightning comes from cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 outside via phone line, electrical induction will cancel out cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 current surge when it hits cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 knot. This was in a Minasi PC repair book I read about 10 years ago.Minasi claims that it saved a modem from a lightning strike after he tried it.

John Ward said...
This comment has been removed by cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 author.
John Ward said...
This comment has been removed by cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 author.
John Ward said...

When I was still working at cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 shop, we would usually get at least 3-4 months of steady business after big lightning strikes. It was usually a combination of people putting off getting immediate repairs, or sets working for a few months afterwards. Usually, voltage regulators and recitifer bridges would break down quicker due to something frying, usually a capacitor or resister. When one of those goes, a circuit "may" still operate, but not necessarily within tolerance. While cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 circuits and IC's that handle cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 frame captures and routing are still recieving cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 5-10 V DC required to operate, that doesn't mean cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 power supply is operating 100% within tolerance. Especially if a component fried before cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 VR. Remember, Voltage Regulators are usually rated for several volts above cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 supplied voltage (example: a 9 volt VR will take as an input anywhere from 12 to 50 volts). So if you fried a resistor before cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 VR, it may still operate for a time, until cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 circuit breaks down. It's all well and good until you smell an electrical fire.

I'd recommend at cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 very least, replace cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 wall wart that came with it, if not scrapping cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 device entirely.

Cereal said...

I don't see why everyone is having such a problem with this. Lighting strikes, a bunch of equipment gets fried. Except for this one piece. He writes about it, and everyone shoots him down.

Think of it this way: If this had been a production enviornment, with phones ringing off cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 hook and a bunch of angry users, you wouldn't be sitting cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365re saying "well, it's working, but we should probably replace cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 A/C adapter that came with it, just in case some flashable EPPROM got scrambled". No, you would just be happy that it was working as you started fixing everything else around it that failed.

sheesh.

John Ward said...

Not worried about cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 flashable proms in cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 tap, Im more worried about cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 voltage regulator, recitifer bridge, and step down circuits being fried. Since its in a lab, who cares about accurate results, I'd be more worried about cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 fact that its in his house, he has children, and is a fire hazard. I think that outweighs any cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365oretical thoughts of "angry users". Im not shooting cá cược thể thao bet365_cách nạp tiền vào bet365_ đăng ký bet365 guy down, Im speaking from experience in a situation where a guy has a lab in a house with children.

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