I notice that when I access to certain China IPv6 sites from the Hong Kong tunnel server (216.218.221.6),
the response time is pretty high considering the distance between China and Hong Kong.
With some curiosity, I start a traceroute to some of the China IPs,
The route goes through the Pacific Ocean twice (hkg1->tyo1->lax2->cngi) before it reached to China.
traceroute to fhk.a.sohu.com (2001:250:208:4000:2000:2:0:2) from 2001:470:18: ??? ?::2, 30 hops max, 16 byte packets
1 ??? ?.tunnel.tserv20.hkg1.ipv6.he.net (2001:470:18: ??? ?::1) 22.068 ms 21.228 ms 21.214 ms
2 ge3-13.core1.hkg1.he.net (2001:470:0:ba::1) 24.715 ms 22.48 ms 24.305 ms
3 10ge3-1.core1.tyo1.he.net (2001:470:0:26a::1) 69.823 ms 71.439 ms 74.788 ms
4 10ge15-2.core1.lax2.he.net (2001:470:0:294::1) 177.837 ms 173.27 ms 173.806 ms
5 cngi-bjix-as-ap-as23911.10gigabitethernet16-5.core1.lax2.he.net (2001:470:0:2a2::2) 171.821 ms 169.559 ms 171.569 ms
6 2001:252:0:302::1 (2001:252:0:302::1) 316.41 ms 322.472 ms 314.04 ms
7 2001:252:0:100::1 (2001:252:0:100::1) 317.197 ms 315.988 ms 316.438 ms
8 2001:252:0:1::1 (2001:252:0:1::1) 313.98 ms 314.283 ms 313.913 ms
9 pku-bj-v6.cernet2.net (2001:da8:1:1b::2) 313.725 ms 315.406 ms 314.876 ms
10 2001:da8:1:50d::2 (2001:da8:1:50d::2) 315.486 ms 315.191 ms 315.801 ms
11 cernet2.net (2001:da8:ac:fff2::2) 314.634 ms 314.549 ms 315.562 ms
12 2001:250:208:f02::2 (2001:250:208:f02::2) 316.082 ms 314.845 ms 314.516 ms
13 2001:4438::1:f002 (2001:4438::1:f002) 315.09 ms 315.128 ms 314.944 ms
14 2001:250:208:4000:2000:2:0:f002 (2001:250:208:4000:2000:2:0:f002) 316.178 ms 317.678 ms 315.865 ms
15 2001:250:208:4000:2000:2:0:f00a (2001:250:208:4000:2000:2:0:f00a) 316.855 ms 324.645 ms 317.474 ms
...
When I check on lg.he.net I found out that there are others routes to the cngi network, through hkg->HKIX->cngi,
which I think the response time will probably be much better than the current path for people using the hkg tunnel.
I wonder the reasons why the previous route is preferred,
is it because the two networks have direct peering in lax?
Probably. Note that network topology doesn't always equal geographic topology.