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14 February 2011

long traceroutes

Physical distance and network distance have an interesting relationship. Even though intra and inter-city links can be horribly slow and therefore not a good measure of physical distance, the same is not as true for international and inter-continental links.

From the UK (a.a.a.a) to Japan (z.z.z.z) via the Internet:

traceroute to z.z.z.z (z.z.z.z), 30 hops max, 40 byte packets
 1  b.b.b.b (b.b.b.b)  0.710 ms  0.606 ms  0.636 ms
 2  c.c.c.c (c.c.c.c)  3.065 ms  2.447 ms  2.817 ms
 3  d.ukcore.bt.net (d.d.d.d)  2.810 ms  2.793 ms  2.483 ms
 4  e.e.e.e (e.e.e.e)  7.235 ms  6.432 ms  7.068 ms
 5  f.ukcore.bt.net (f.f.f.f)  6.449 ms  6.360 ms  6.221 ms
 6  * g.eu.bt.net (g.g.g.g)  6.151 ms  5.906 ms
 7  h.eu.bt.net (h.h.h.h)  88.322 ms  88.575 ms  88.227 ms
 8  i.eu.bt.net (i.i.i.i)  88.652 ms  88.257 ms  88.850 ms
 9  * * *
10  j.j.j.j (j.j.j.j)  164.092 ms  163.958 ms  163.862 ms
11  k.kddnet.ad.jp (k.k.k.k)  151.157 ms  150.945 ms  150.999 ms
12  l.kddnet.ad.jp (l.l.l.l)  262.545 ms  264.215 ms  262.769 ms
13  m.kddnet.ad.jp (m.m.m.m)  284.810 ms  278.666 ms  276.577 ms
14  n.kddi.ne.jp (n.n.n.n)  270.713 ms  270.666 ms  282.805 ms
15  o.kddi.ne.jp (o.o.o.o)  278.036 ms  278.105 ms  278.458 ms
16  p.kddi.ne.jp (p.p.p.p)  269.161 ms  266.220 ms  270.104 ms
17  q.kddi.ne.jp (q.q.q.q)  279.407 ms  283.477 ms  279.755 ms
18  r.r.r.r (r.r.r.r)  295.864 ms  266.645 ms  267.897 ms
19  s.s.s.s (s.s.s.s)  268.964 ms  268.345 ms  267.745 ms
20  z.jp (z.z.z.z)  265.074 ms  275.107 ms  263.744 ms


The key hops are 6 to 7 (~82ms) [UK-Europe], 8 to 10 (~76ms) [Europe-Japan] and 11 to 12 (~110ms). These represent the respective network distances of the links between UK and somewhere in Europe and between somewhere in Europe and Japan.

From the UK (a.a.a.a) to Australia (z.z.z.z) via a private link:

traceroute to z.z.z.z (z.z.z.z), 30 hops max, 40 byte packets
 1  b.b.b.b (b.b.b.b)  0.522 ms  0.491 ms  0.827 ms
 2  c.c.c.c (c.c.c.c)  2.811 ms  2.788 ms  2.753 ms
 3  d.d.d.d (d.d.d.d)  0.567 ms  0.543 ms  0.515 ms
 4  e.e.e.e (e.e.e.e)  0.467 ms  0.771 ms  0.556 ms
 5  f.f.f.f (f.f.f.f)  6.864 ms  8.488 ms  11.544 ms
 6  g.g.g.g (g.g.g.g)  305.581 ms  306.083 ms  306.598 ms
 7  z.z (z.z.z.z)  305.507 ms  305.506 ms  305.377 ms


In this case, the important hops are 4 to 5 (~8ms) [likely intercity] and 5 to 6 (~295ms) [obviously intercontinental].

An interesting trivia to take away from the latter case is packets travelled half the world and back at a difficult-to-conceive 408 216 000 km/h or 253 653 663 mph. Or in a scientific perspective 0.378*c [where c is approximately the speed of light in vaccum].

My trusty UDP packets travelled half the world and back at an amazing ~37.8% of the speed of light! That's including routing and other network type processing, variable speeds of propagation trough different mediums, etc.