nanog mailing list archives

Re: T3 Latency


From: Charles Scott <cscott () gaslightmedia com>
Date: Sat, 17 Feb 2001 09:33:02 -0500 (EST)



Matthew:
  Appears to be a typo in your final number of 130 mi/sec, but I get where
you're going with this. I'm just having a problem trying to figure out how
I end up with a couple thousand fiber miles from Northern Michigan to
Chicago. Should be interesting to sort this one out.

Thanks,

Chuck


On Sat, 17 Feb 2001, Matthew F. Ringel wrote:


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



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