Long haul latency calculation?
Dear Nanog: I was wondering if there is a benchmark for long-haul circuit latency... For example if I had a T1 circuit with 2900 miles between the two end-points (and assuming the provider is best case scenario) can I do something like (miles*latencyfactor) = 5 ms for 2900 miles? Thanks, Christopher
Hi Chris, On long haul and reasonable bandwidth, I figure as a rough estimate to divide the distance in kilometers by 100 will be a very close approximation to an RTT in ms. For instance I get 147 ms ICMP RTT on the Southern Cross Sydney-Seattle link where the fibre path is about 14700 km. It assumes a transmission speed close to .66 the speed of light. The calculation using miles is a little messier ;-) Bruce
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of Christopher Wolff Sent: Monday, 1 October 2001 12:09 PM To: nanog@merit.edu Subject: Long haul latency calculation?
Dear Nanog:
I was wondering if there is a benchmark for long-haul circuit latency... For example if I had a T1 circuit with 2900 miles between the two end-points (and assuming the provider is best case scenario) can I do something like (miles*latencyfactor) = 5 ms for 2900 miles?
Thanks, Christopher
Christopher Wolff wrote:
I was wondering if there is a benchmark for long-haul circuit latency... For example if I had a T1 circuit with 2900 miles between the two end-points (and assuming the provider is best case scenario) can I do something like (miles*latencyfactor) = 5 ms for 2900 miles?
Speed of light is apprxoximately 2.998e+8 m/s (or 299,800,000 m/s), which is approximately 186,287 miles/sec. 2900 mi / 186,287 mi/s = 0.01557s = 15.57ms. This is the absolute minimum latency you can possibly get over that distance. Switching performance and congestion will make your actual latency somewhat larger. -- David
participants (3)
-
Bruce Morgan -
Christopher Wolff -
David Charlap