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jtwn
11-04-2005, 13:18
What causes the jump in ping times from one side of the atlantic to the other, i notice that the massive jump is always the hop from when it goes overseas?

Is it just the simple lag time it takes to get from one side of the ocean to the other (i thought fibre was lightspeed?) or are whatever deals with the data at either end overloaded?

SMHarman
11-04-2005, 13:25
The distance - even at light speed 4000 miles takes a little time.
Also the conversion to from fiber data at the fibre switches adds some ms. Also the distance adds more machines and routing points which all will add an extra 20ms or so.

Ignition
11-04-2005, 14:22
The distance - even at light speed 4000 miles takes a little time.
Also the conversion to from fiber data at the fibre switches adds some ms. Also the distance adds more machines and routing points which all will add an extra 20ms or so.

Nah, it's virtually all distance, fibre routes to the USA tend not to be absolutely direct, especially if you remember that they are rings, so if the light can't take the most direct path along the ring due to damage it can easily add an extra couple of thousand KM onto the trip. (Big fibre routes tend to have one side UK->NY and another side from us UK->Continental Europe->Scandinavia->NY).

The delay at the muxes and repeaters is microseconds and not really significant, they are very very good at what they do.

EDIT: PS you're thinking of conversion from optical to electrical, and at multiplexers and repeaters (of which there are numerous repeaters scattered along the Atlantic route) rather than switches, which are short haul layer 2 devices usually used in data centres, etc, and only found on land.

The actual SDH switching is all done at muxes above ground, more optical repeaters. Plenty of these along the way.
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Is it just the simple lag time it takes to get from one side of the ocean to the other (i thought fibre was lightspeed?) or are whatever deals with the data at either end overloaded?

Optical transmission is about 2/3rds light speed - the light is bouncing off the sides of the fibre which adds 50% or so to the distance.

jtwn
11-04-2005, 15:46
Thanks for replies :)