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Robust Timing Over the Internet
ChelleChelle writes "The NTP (Network Time Protocol) system for synchronizing computer clocks has been around for decades and has worked well for most general-purpose timing uses. However, new developments, such as the increasingly precise timing demands of the finance industry, are driving the need for a more precise and reliable network timing system. Julien Ridoux and Darryl Veitch from the University of Melbourne are working on such a system as part of the Radclock Project. In this article they share some of their expertise on synchronizing network clocks. The authors tackle the key challenge — taming delay variability — and provide useful guidelines for designing robust network timing algorithms."
How about GPS receiver + exact known location?
I would think just eliminating an unknown latency and replacing it with a known one (radio waves generally travel at a consistent rate) would get you a pretty accurate time. If you add one more known variable which is the exact location of the device, then you should be able to get an even more accurate time.
Microsoft refuses to consider the notion of clocks accurate to within 2 seconds.
I'm surprised the article didn't mention PTPd, which is an implementation of the IEEE 1588 precision time-synchronization standard. I was under the impression that was the standard way to solve this sort of problem when NTP wasn't enough.
I don't care if it's 90,000 hectares. That lake was not my doing.
It's not clear to me the financial system needs such high precision timing.
My cynicism tells me they need it now to implement fraudulent micro-second trading, where see what you're buying, correlate with other people's buys and then buy a fraction of a second ahead of you.
At any rate, it's not clear they need it, or that giving it to them won't lead to instability.
Maybe someone should actually design a financial system, and design one that can use imprecise, or precision timing.
NTP is accurate to within 10 milliseconds in any decent connection. Get a really good, stable, low latency connection and hook yourself up to a stratum 1 server and you can cut that number down tenfold ...
Can anyone explain what kind of financial application would require bigger accuracy?
I understand that certain scientific experiments require more accuracy than that, but those guys are probably already hooked up to stratum 0 servers directly.
Why on earth would any financial system (yes, even the stock market) require 10ms time accuracy? They were able to rip us off with fucking sand clocks. NTP should be enough for them.
WTF am I doing replying to an AC at 5 A.M on a Friday night?
let's do away with the arbitrage, gambling, and bullshit from wall street. make them own a stock for ONE WHOLE DAY. No more of this low-latency trading bullshit.
A Capital Gains Tax that started at 95% and decreased ~2.5% per month would go a long way towards fixing many problems (/avoiding them in the first place).
Network issues. If say, on average, once every 25 polls, ntpd doesn't get realistic data from higher stratum servers because of the network, don't let ntpd crank up the frequency to ridiculous values like it does when this occurs.
There are realistic values for the frequency on every machine with a good clock. It is ridiculous to set the frequency below or above these values.
Last time I checked, there is no way in ntpd to configure these values. The typical ntp guru reply will be: "Get a decent network connection". The author in TFA noted that such a "decent connection" is virtually impossible to achieve because of "variable delay". He also noted that it is sometime better to trust yourself, which is kind of what that script does.
Everything I write is lies, read between the lines.
Author of TFA also mention:
"More generally, the algorithm should be designed never to overreact to anything. Remember, its view of the world is always approximate and may be wrong, so why try to be too clever when inaction works so well? Unfortunately, feedback algorithms such as ntpd have more reactive strategies that drive the clock more strongly in the direction of their opinions. This is a major source of their nonrobustness to disruptive events."
I fully agree with this and I realized it several years ago while testing ntpd in various configurations.
Everything I write is lies, read between the lines.
Hi!
Last few years, most cellular operators are rolling out IP to the base stations.
For HSPA/LTE speeds, E1/T1 PDH/ATM is out of the question,
and as IP is rolled out, GSM gets there as well.
Accurate timing is essential: even transmitter frequency is synchronized over IP,
and keeping 2 GHz accurate to 100 Hz is not simple.
Local oscillator can do it short term, but external correction is needed as well.
Beside GPS (used in IS-95), several systems are used.
IEEE 1588v2 is obvious one. Works.
Some vendors do it with modified NTP: generate a lot of requests, and do some statistic processing.
Thus, most of the jitter can be compensated, and accuracy can be kept.
Normally, it works over intranets, with NTP having high priority, but it is used over internet as well
(femto and pico base stations).
Real life tests indicate it works, just do not put it over ADSL ;-)
73
Iztok
That's a ridiculous idea. It would increase volatility tremendously, increase spreads tremendously, increase mispricing tremendously, and of course destroy any semblance of liquidity for half the securities out there. Saying that arbitrageurs are skimming is like saying market makers are skimming. Partly true, but it completely ignores the positive effects of their actions for the market.
Infinite time means everything that can happen, will. You being you is absolutely incidental. You do not exist.
Who the hell isn't greedy. If you were offered more money at work, would you turn it down. Most people wouldn't. And all your colleagues are going to get paid more.
This is all these people are doing, they are doing there jobs, and they get paid bonuses for doing it well.
It is ignorant and stupid to pretend that this situation is just that simple.