I have a customer with IP transport from Sprint and McLeod and fiber
connectivity to Sprint in the Chicago area. The person making the
decisions is not a routing guy but is very sharp overall. He is
currently examining the latency on trans-Atlantic links and has fixed on
the idea that he needs 40ms or less to London through whatever carrier
he picks. He has spoken to someone at Cogent about a point to point link.
What is a reasonable latency to see on a link of that distance? I
get the impression he is shopping for something that involves dilithium
crystal powered negative latency inducers, wormhole technology, or an
ethernet to tachyon bridge, but its been a long time (9/14/2001, to be
exact) since I've had a trans-Atlantic circuit under my care and things
were different back then.
Anyone care to enlighten me on what these guys can reasonably
expect on such a link? My best guess is he'd like service from Colt
based on the type of customer he is trying to reach, but its a big
muddle and I don't get to talk to all of the players ...
Chicago to London: ~3950 mi
New York to London: ~3470 mi
c == 186,282 mi/sec (in a vacuum)
0.66 * c == 122,946 mi/sec
CHI-LON: 32.128 ms
NYC-LON: 28.224 ms
That is one way, absolute best case, and the cables never run quite
the way you want them to. If he's looking for 40 ms RTT, he is not going to
get it. If he just needs 40 ms one way to London, it is possibly doable,
even from Chicago.
I couldn't readily find lengths for the individual segments of
TAT-14, so as a representative example, we'll use TAT-12/13. From RI to
the UK: 3,674 mi.
( 3674 / (0.66 * c) ) * 1000 == 29.883 ms, doubled for 59.766 ms
RTT.
Real world numbers seem to suggest many carriers run between 70 and
80 ms RTT from NYC to London, and I just measured around 100 ms RTT from
Chicago to a host in the UK.
I have a customer with IP transport from Sprint and McLeod and fiber
connectivity to Sprint in the Chicago area. The person making the
decisions is not a routing guy but is very sharp overall. He is
currently examining the latency on trans-Atlantic links and has fixed on
the idea that he needs 40ms or less to London through whatever carrier
he picks. He has spoken to someone at Cogent about a point to point link.
Paging Scotty, warp factor 4 please!
What is a reasonable latency to see on a link of that distance? I
get the impression he is shopping for something that involves dilithium
crystal powered negative latency inducers, wormhole technology, or an
ethernet to tachyon bridge, but its been a long time (9/14/2001, to be
exact) since I've had a trans-Atlantic circuit under my care and things
were different back then.
The speed of light hasn't changed much.
Propagation delay alone, assuming a 3000 mile straight-line path (probably on the short side) and 0.7 velocity factor in the transport medium is around 45 milliseconds round trip. Chicago to the East coast is about another 1000 miles or 15 ms, so 60ms. is probably a bit on the low side.
Serialization delay depends on bit rate and packet size, easy enough to calculate.
Sprint has probably the lowest latency in the industry; I use them for a Los Angeles - London IPSec VPN. Typical latency is around 140-150 ms rt (70-75 ms one-way)
40 ms RT is not possible in this reality, unless the speed of light is increased or one transimits through subspace (see Star Trek)
I have a customer with IP transport from Sprint and McLeod and fiber
connectivity to Sprint in the Chicago area. The person making the
decisions is not a routing guy but is very sharp overall. He is
currently examining the latency on trans-Atlantic links and has fixed on
the idea that he needs 40ms or less to London through whatever carrier
he picks. He has spoken to someone at Cogent about a point to point link.
What is a reasonable latency to see on a link of that distance? I
get the impression he is shopping for something that involves dilithium
crystal powered negative latency inducers, wormhole technology, or an
ethernet to tachyon bridge, but its been a long time (9/14/2001, to be
exact) since I've had a trans-Atlantic circuit under my care and things
were different back then.
Anyone care to enlighten me on what these guys can reasonably
expect on such a link? My best guess is he'd like service from Colt
based on the type of customer he is trying to reach, but its a big
muddle and I don't get to talk to all of the players ...
I remember voiping over the pond, from Frankfurt, germany to New York.
We had to twist asterisk to even accept the sip. Time was between
80 and 90 msec. The experienced time was higher. Roger, Over and Out
with their interstallar hamradio experience could do it, but to a
normal citizen it was unuseble.
I have a customer with IP transport from Sprint and McLeod and fiber
connectivity to Sprint in the Chicago area. The person making the
decisions is not a routing guy but is very sharp overall. He is
currently examining the latency on trans-Atlantic links and has fixed on
the idea that he needs 40ms or less to London through whatever carrier
he picks. He has spoken to someone at Cogent about a point to point link.
What is a reasonable latency to see on a link of that distance? I
get the impression he is shopping for something that involves dilithium
crystal powered negative latency inducers, wormhole technology, or an
ethernet to tachyon bridge, but its been a long time (9/14/2001, to be
exact) since I've had a trans-Atlantic circuit under my care and things
were different back then.
Anyone care to enlighten me on what these guys can reasonably
expect on such a link? My best guess is he'd like service from Colt
based on the type of customer he is trying to reach, but its a big
muddle and I don't get to talk to all of the players ...
I remember voiping over the pond, from Frankfurt, germany to New York.
We had to twist asterisk to even accept the sip. Time was between
80 and 90 msec. The experienced time was higher. Roger, Over and Out
with their interstallar hamradio experience could do it, but to a
normal citizen it was unuseble.
He'll need a Black & Dekker drill with a hammer attachment, and an
absolutely prodigious stone cutting bit, a convenient wormhole, or a
waiver on the laws of physics.
