Network latency -- how long does it take for a packet to travel halfway around the world?

Possible Duplicates:
How does geography affect network latency?
How much network latency is “typical” for east - west coast USA?

If I'm hosting an app in NY, what kind of delay can I expect for a user to get a single packet if they're in Australia, i.e. roughly the maximum distance from NY?

I'm looking for the maximum latency I'm likely to encounter on a regular basis -- if Australia's not the right destination point to consider, feel free to substitute another point.

Thanks!

Michael

From serverfault kaneuniversal

• This is hard to come by information, as You might know, because it is related to the individual endpoints and the way they are switched to the destination, especially partly even how their individual provider is switched and prioritized over the deep sea cables between the continents. Also it wildly differs from desination continent to destination continet as sometimes traffic for one continet is routed throgh another continent (read sea cables). Also it seems that the part between fiber lines and each endpoint is what brings the latency, so it seems to be more about the customer's internet connection than the Backbone You're sitting on. Be sure to have a look at the links provided by Zypher and Ward.

  If latency is a problem, think about a content delivery network, which serves each continent on the continent. That might help if You don't need data written to Your NY server in realtime.

  Cisco has some tiny bits for VOIP, but worthwile to read, there is a forum thread with some user measurements. The numbers differ wildly but never forget that users often mix up ping and lateny (like in the forum posts).

  Personally I would expect about 200 milliseconds end to end just to be sure.

  The thing I would do, would be to take an edonkey client with latency readings (I believe azureus has this) and have a look at connections from my destination to interesting spots on the map. That way You have raeal life end to end latency data.

  From deploymonkey

• If you had a fiber optic cable straight from NY to Sydney, the distance latency by itself would be ~90ms. Realistically you'd be lucky to stay under 200ms.

  From Chris S