Bad 6to4 routing through AS1103 AS2914

[Daniel G. Kluge]

Hello there,
I'm using everybody's favorite random bit-bucket 6to4, and found some  
strange routing.

The IPv6 trace goes as follows from AS8404 (Cablecom CH) to AS559  
(Switch CH):

traceroute6 to oreius.switch.ch (2001:620:0:1b::b) from 2002:4d39:xxx: 
1337::1, 30 hops max, 12 byte packets
1  2002:4d39:xxxx:1337::1 (2002:4d39:xxxx:1337::1)  0.858 ms  0.427  
ms  0.413 ms
2  2002:c058:6301:: (2002:c058:6301::)  138.943 ms  134.219 ms   
123.884 ms
3  v2-1-1-2076.xsr01.asd002a.surf.net (2001:610:f01:9012::13)   
124.987 ms *  126.991 ms
4  ft-500.xsr03.asd001a.surf.net (2001:610:e08:32::34)  143.284 ms   
147.892 ms  125.722 ms
5  surfnet.rt1.ams.nl.geant2.net (2001:798:22:10aa::1)  79.299 ms   
86.309 ms  113.57 ms
6  so-6-2-0.rt1.fra.de.geant2.net (2001:798:cc:1401:2201::1)  79.536  
ms  76.094 ms  72.934 ms
7  so-6-2-0.rt1.gen.ch.geant2.net (2001:798:cc:1201:1401::1)  72.457  
ms  73.24 ms  82.032 ms
8  switch-gw.rt1.gen.ch.geant2.net (2001:798:12:10aa::2)  73.404 ms   
72.459 ms  90.758 ms
9  swils2-10ge-1-3.switch.ch (2001:620:0:c006::2)  33.574 ms  45.307  
ms  31.616 ms
10  swicp2-g1-0-28.switch.ch (2001:620:0:c048::1)  30.143 ms  61.292  
ms  34.204 ms
11  oreius.switch.ch (2001:620:0:1b::b)  33.33 ms  29.719 ms  35.477 ms

So the problem seems to be the 6to4 relay on hop 2, which is actually  
at Surfnet (AS1103), and looks fine:
traceroute to 192.88.99.1 (192.88.99.1), 64 hops max, 40 byte packets
5  213.46.160.45 (213.46.160.45)  21.763 ms  36.532 ms  19.972 ms
6  de-fra01a-rd1-10ge-0-0.aorta.net (213.46.179.5)  19.749 ms  20.109  
ms  19.652 ms
7  nl-ams05a0-rd1-pos-2-0.aorta.net (213.46.160.197)  34.924 ms   
36.641 ms  35.109 ms
8  nl-ams02a-ra1-10ge-3-0-0-0.aorta.net (213.46.183.101)  39.883 ms   
35.190 ms  36.001 ms
9  nl-ams04a-ri1-ge-5-0.aorta.net (213.46.183.78)  36.222 ms  36.830  
ms  36.035 ms
10  gbe3-5-6.xsr03.amsterdam1a.surf.net (145.145.166.45)  35.618 ms   
41.396 ms  35.917 ms
11  tf-500.xsr01.amsterdam2a.surf.net (145.145.80.33)  37.783 ms   
53.958 ms  37.401 ms
12  onweer.surfnet.nl (145.145.19.14)  37.471 ms *  36.670 ms

But then where does the return path go through? Thanks to sixxs'  
distributed traceroute we get:
IPv6 traceroute from nlams05.sixxs.net @ SURFnet, AS1103 to  
2002:4d39:xxxx:1337::1 :
Hop  Node                         Loss%  Sent   Last   Avg  Best  
Worst StDev       ASN        Organisation
   1. 2001:610:1:80bb:192:87:102:9  0.0%     5    0.6   0.6   0.5    
0.6   0.0     1103       SURFnet
   2. 2001:610:f01:9168::174        0.0%     5    1.1   1.4   1.1    
1.6   0.2     1103       SURFnet
      v2-1-1.1661.XSR01.Amsterdam2A.surf.net.
   3. 2001:610:e08:32::34           0.0%     5    1.6   1.5   1.4    
1.6   0.1     1103       SURFnet
      FT-500.XSR03.Asd001A.surf.net.
   4. 2001:7f8:1::a500:2914:1       0.0%     5    1.4   1.4   1.4    
1.5   0.1
      ge-0.ams-ix.amstnl02.nl.bb.verio.net.
   5. 2001:418:0:2000::105          0.0%     5   99.6  99.6  99.3  
100.0   0.3                Verio, Inc.
      p64-1-1-0.r20.asbnva01.us.bb.gin.ntt.net.
   6. 2001:418:0:2000::1e6          0.0%     5   99.6  99.6  99.3   
99.6   0.1                Verio, Inc.
      xe-1-1.r01.stngva01.us.bb.gin.ntt.net.
   7. 2001:418:0:5000::36           0.0%     5  101.1 101.2 101.0  
101.4   0.2                Verio, Inc.
      fa-0-0.gw.stngva.ameri.ca.
   8. 2002:4d39:xxxx::1             0.0%     5  124.9 126.0 124.9  
128.3   1.4                6to4
   9. 2002:4d39:xxxx:1337::1       20.0%     5  126.7 126.9 125.4  
128.8   1.4                6to4


So it seems that AS1103, even though they advertise a 6to4 relay,  
don't have a reverse path, and chuck it over the fence to Verio. But  
in AS2914 the 6to4 gateway seems to be located in the US, so we have  
again the big-pond hopping routes that made IPv6 a PITA to use in the  
beginning.

So could we get something more reasonable, routing-wise? Either  
AS1103 or AS2914 should terminate 2002::/16 locally and send it to  
IPv4-land, or at least send it to someone who will do so in Europe.

Geant in the first traceroute is slightly better, they route  
2002::/16 through Lisbon (fccn.pt, hello Carlos) and back (LIS-LDN- 
PAR-FRA-ZUR).

Cheers,
-daniel (I know I should set up a tunnel, but this is more fun)
P.S. according to GRH AS1103 seems to be missing 2002::/16, so how  
that routes in the first place...