6to4 borkeness (Was: Google and IPv6)

Wed Mar 19 17:26:32 CET 2008

> FWIW, my experience with 6to4 is more positive than Jeroen's. It
> works almost all the time for me, except when someone breaks the
> 2.0.0.2.ip6.arpa zone, but that hasn't happened for months. Mind
> you, many of the ISPs that I regurally use have their own relays
> or a relay close by.
> 
> For me, debugging 6to4 hasn't proved that much harder than anything
> else. You can find the relay at your end by tracerouting to
> 192.88.99.1.  It's true that the reverse path is hard to debug, but
> that's the same no matter what you're using. It was a little easier
> in IPv6 when we had RH0 (though I know Jeroen prefers looking glasses
> for this sort of thing).

Ok, so I've noticed that I'm not able to reach hinet.net at all, pretty
consistently.  It's possible the site is just broken on it's own, but I
do see a significant discrepancy in traceroutes from my network and from
he.net's looking glass.  Perhaps this would be a good chance to help me
learn how to debug my routes better.  Just let me know if this is a lost
cause without hinet.net's help.  Here's from my machine:

-------------8<-----------------
~> tracepath6 -n 2001:b000:0:0:0:0:0:1021
 1?: [LOCALHOST]                      pmtu 1500
 1:  2002:4775:eda1:2::                 0.392ms 
 1:  2002:4775:eda1:2::                 0.329ms 
 2:  2002:4775:eda1:2::                 0.327ms pmtu 1480
 2:  2002:c058:6301::                  81.636ms 
 2:  2002:c058:6301::                  79.926ms 
 3:  2001:4978:1:410::ffff             82.114ms asymm  4 
 4:  no reply
 5:  2001:1888::1:a:2                 450.096ms asymm  2 
 6:  2001:b02a:0:b::1                 432.455ms asymm 12 
 7:  no reply
...

:~> traceroute6 -n 2001:b000:0:0:0:0:0:1021
traceroute to 2001:b000:0:0:0:0:0:1021 (2001:b000::1021) from
2002:4775:eda1:2::3:0, 30 hops max, 24 byte packets
 1  2002:4775:eda1:2::  1.895 ms  0.078 ms  0.491 ms
 2  2002:c058:6301::  76.131 ms  74.929 ms  74.745 ms
 3  2001:4978:1:410::ffff  137.605 ms  74.744 ms  75.724 ms
 4  * * *
 5  2001:1888::1:a:2  360.029 ms  519.85 ms  359.913 ms
 6  2001:b02a:0:b::1  334.673 ms  535.475 ms  334.666 ms
 7  2001:b000::1021  442.407 ms  334.678 ms  335.287 ms
------------->8-----------------

And then nearly every trace from all of the different he.net locations
look like:

-------------8<-----------------
AMS-IX Amsterdam, NL :

Tracing the route to IPv6 node 2001:b000::1021 from 1 to 30 hops

  1   278 ms    8 ms   12 ms 2001:470:0:3f::1 
  2    77 ms   77 ms   77 ms 2001:470:0:3e::1 
  3   156 ms  156 ms  156 ms 2001:470:0:33::1 
  4   157 ms  167 ms  157 ms 2001:470:0:32::2 
  5   294 ms  289 ms  300 ms 2001:504:d::ae 
  6   289 ms  289 ms  289 ms 2001:288:3b0:7::20 
  7   298 ms  288 ms  289 ms 2001:288:3b0:3::1 
  8   310 ms  300 ms  300 ms 2001:288:3b0:4::2 
  9   305 ms  289 ms  289 ms 2001:288:3b0:5:0:1:7419:1 
 10   290 ms  297 ms  302 ms 2001:b000::1021 
Storing [core1.ams1.he.net trace ipv6 2001:b000:0:0:0:0:0:1021]

...

Equinix Ashburn, VA :

Tracing the route to IPv6 node 2001:b000::1021 from 1 to 30 hops

  1  1105 ms   75 ms   88 ms 2001:470:0:35::1 
  2   206 ms  219 ms  207 ms 2001:504:d::ae 
  3   207 ms  212 ms  275 ms 2001:288:3b0:6::20 
  4   206 ms  206 ms  214 ms 2001:288:3b0:3::1 
  5   206 ms  206 ms  213 ms 2001:288:3b0:4::2 
  6   208 ms  218 ms  207 ms 2001:288:3b0:5:0:1:7419:1 
  7   218 ms  211 ms  216 ms 2001:b000::1021 
Storing [core1.ash1.he.net trace ipv6 2001:b000:0:0:0:0:0:1021]

...

Hurricane Fremont-2, CA :

Tracing the route to IPv6 node 2001:b000::1021 from 1 to 30 hops

  1     9 ms   <1 ms   <1 ms 2001:470:0:30::2 
  2   135 ms  152 ms  147 ms 2001:504:d::ae 
  3   152 ms  148 ms  152 ms 2001:288:3b0:7::20 
  4   147 ms  153 ms  147 ms 2001:288:3b0:3::1 
  5   153 ms  147 ms  152 ms 2001:288:3b0:4::2 
  6   148 ms  153 ms  148 ms 2001:288:3b0:5:0:1:7419:1 
  7   152 ms  148 ms  152 ms 2001:b000::1021 
Storing [core1.fmt2.he.net trace ipv6 2001:b000:0:0:0:0:0:1021]
------------->8-----------------

Note how none of the he.net traces goes through 2001:1888::1:a:2 or
2001:b02a:0:b::1, and the latter has a wicked asym.

However, if I use sixxs.net's traceroute from your.org, which I guess I
am 6to4 tunneling through:

-------------8<-----------------
IPv6 traceroute
IPv6 traceroute from uschi02.sixxs.net @ Your.Org, Inc., AS19255 to 2001:b000:0:0:0:0:0:1021 :

Hop  Node                         Loss%  Sent   Last   Avg  Best Worst StDev       ASN        Organisation
  1. 2001:4978:1:400::ffff         0.0%     5    3.5   3.4   3.3   3.5   0.1    [.us] United States 19255      YOUR.ORG, INC.
     sixxs.ge-0.0.0-30.core1.chi.bb6.your.org.
  2. 2001:1888::1:8:1              0.0%     5  115.5 114.9 114.4 115.5   0.5    [.us] United States 6435       LavaNet, Inc.
     tunnel-your-lavanoc.lava.net.
  3. 2001:1888::1:a:2              0.0%     5  493.2 412.2 326.1 546.2 101.5    [.us] United States 6435       LavaNet, Inc.
     tunnel-chttl-tw.lava.net.
  4. 2001:b02a:0:b::1              0.0%     5  264.0 281.2 264.0 320.1  25.1    [.tw] Taiwan            HiNet Taiwant
  5. 2001:b000::1021              20.0%     5  267.8 266.2 264.3 268.4   2.2    [.tw] Taiwan            HiNet Taiwant

When the ASN of a prefix is blank then the prefix doesn't have an route6 entry in the registries. 

------------->8-----------------

It seems to work ok, though there is some loss I guess.  Other things I
should try?

thanks again,
tim