5 ms·
Depends on what you do. For what I do, Ethernet is acceptable as long as the latency is below 1 ms. Here're some quick stats for what I consider good enough th
by devereaux 8y ago
Depends on what you do.
For what I do, Ethernet is acceptable as long as the latency is below 1 ms. Here're some quick stats for what I consider good enough this specific usecase:
rtt min/avg/max/std-dev = 0.069/0.095/0.121/0.016 ms
Generally it is better to keep things simple and use existing stuff whenever possible.
If we are talking about very low latency (say below 30 us) you may need many other things first, like a good timesource.
Then indeed, when you start rolling your own stratum1 NTP servers, rolling your own protocols can be a sensible answer to the problem you have.
- MuffinFlavored 8y agoAt a high level, what do you do with HFT? You aren't doing the trading, right? You just manage the systems behind it? So what is? Are there really bots "in production" that are making buying and selling decisions tied to real money so quickly that <1ms is needed?
- walrus01 8y agoI'm not directly involved with it, but tangentially at a network engineering level. In things like the NYC-Chicago path, 1 millisecond is an ETERNITY. The actual people working for HFT firms are probably not going to provide much insight into what's going on behind the scenes, due to very restrictive NDAs, security policies and litigious corporate overlords.
- dmurray 8y agoThe advantage is being first. If you learn in Tokyo that a stock is going to go up, you can buy all of the available stock in New York, or cancel your order to sell it. It's going to take you 50 ms to get that information to New York, but if your competitor takes 49 ms, you lose money; if he takes 51 ms, you make money. So 1 ms is important, and so is any time difference big enough to outweigh the noise in the exchange's ordering of events. I know people measuring and caring about speed gains of single-digit nanoseconds, roughly equivalent to replacing your two-metre cables with one-metre cables. The end customer (whoever actually wants to buy stocks) doesn't need the price to update every millisecond. But no one has yet figured out a better way to run an electronic exchange than "first come, first served". Source: also worked in HFT for a long time.
- kevin_thibedeau 8y agoWhy would you screw around with NTP when you could just use PTP capable infrastructure?
- devereaux 8y agoI have my reasons. I see PTP as a good complement to NTP.