North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: T3 Latency
The rule of thumb I use is that the speed of light in fiber-optic cable is roughly 2x10^8 m/sec. 2x10^8 m/sec = 200,000,000 m/sec = 200,000 km/sec = 200 km/msec =~ 130 mi/sec I once worked with a customer whose first hop out was ~30ms, regardless of the load on the line (a t3, iirc). Sure enough, he was on a very large SONET ring that travelled the north-south length of the US roughly twice before his traffic went elsewhere. ......Matthew ---------- M. F. Ringel Network Engineer Akamai Technologies, Inc. [email protected] On Sat, Feb 17, 2001 at 07:37:48AM +0000, Walter Prue wrote: > > Chuck, > > The question posed by Chris, "how long is your access line"?, is a rather > important data point before answering your question. I have a T3 that is > about 15 miles long. It runs between two 7500 routers. Its minimum ping > round trip time with 100 byte pings is 2 ms. It is not very heavily loaded > with peaks of about 10 Mb/s today and the max round trip time was 21 ms. > > So that should give you some minimal bounds of what you might expect. As > the saying goes your mileage may vary. Speed of light does play in here, > if the circuit is longer. Also intervening electronics such as a frame cloud > or telco muxes also add latency. > > Walt >
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