High ping time from a Hong Kong tunnel to China IPv6 sites

[karlc]

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?

[snarked]

Probably.  Note that network topology doesn't always equal geographic topology.