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Author Topic: Strange traceroute behavior with IPv6 tunnel  (Read 2531 times)

ricrjhl

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  • Posts: 4
Strange traceroute behavior with IPv6 tunnel
« on: February 16, 2011, 11:46:54 AM »

Hello All,

Situation is as follows:

    - Ubuntu 10.10 server (64 bits) with latest patches
    - HE tunnel to Amsterdam
    - Beyond the things below nothing else is modifyed on the server

There are two ways i can setup my tunnel:

1. By adding entry below to /etc/network/interfaces
Code: [Select]
auto he-ipv6
iface he-ipv6 inet6 v4tunnel
     endpoint 216.66.84.46
     address <MyIPv6 tunnel endpont>
     netmask  64
     up ip -6 route add default dev he-ipv6
     down ip -6 route del default dev he-ipv6

2. Manually using the following script
Code: [Select]
ip tunnel add he-ipv6 mode sit remote 216.66.84.46 local <MyIPv4>  ttl 255
ip link set he-ipv6 up
ip addr add <MyIPv6 tunnel endpoint>/64 dev he-ipv6
ip route add ::/0 dev he-ipv6

Both work but there is a difference which can be seen when i do a traceroute6 over the IPv6 connection

1. Traceroute6 to heise.de with "By adding entry below to /etc/network/interfaces"
Code: [Select]
traceroute to heise.de (2a02:2e0:3fe:100::8) from <MyIPv6 tunnel endpoint>, 30 hops max, 24 byte packets
 1  * * *
 2  * * *
 3  * * *
 4  * * *
 5  * * *
 6  redirector.heise.de (2a02:2e0:3fe:100::8)  22.275 ms  22.164 ms  23.276 ms

2. Traceroute6 to heise.de with "Manually using the following script"
Code: [Select]
traceroute to heise.de (2a02:2e0:3fe:100::8) from <MyIPv6 tunnel endpoint>, 30 hops max, 24 byte packets
 1  <MyTunnelName>.ams1.ipv6.he.net (<Tunnel endpoint at he.net>)  20.525 ms  20.378 ms  19.956 ms
 2  gige-g2-20.core1.ams1.he.net (2001:470:0:7d::1)  15.225 ms  15.633 ms  13.341 ms
 3  10gigabitethernet1-1.core1.fra1.he.net (2001:470:0:47::2)  30.86 ms  24.918 ms  25.022 ms
 4  te3-1.c101.f.de.plusline.net (2001:7f8::3012:0:1)  136.741 ms  630.423 ms  337.335 ms
 5  te6-1.c13.f.de.plusline.net (2a02:2e0:1::1e)  21.389 ms  21.222 ms  23.284 ms
 6  redirector.heise.de (2a02:2e0:3fe:100::8)  25.96 ms  22.307 ms  21.208 ms

Why does the first tunnel not show any reponses from the systems in between me and heise.de whilst the other one does ?  If anyone has an idea why please let me know.

Richard.
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ricrjhl

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  • Posts: 4
Re: Strange traceroute behavior with IPv6 tunnel
« Reply #1 on: February 16, 2011, 01:27:59 PM »

No help needed anymore, found the problem. The solution is adding 1 extra line to /etc/networks/interfaces for the definition of the he-ipv6 interface. You need to specify "ttl".

Correct entry would then look as follows:
Code: [Select]
auto he-ipv6
iface he-ipv6 inet6 v4tunnel
     endpoint 216.66.84.46  # HE Amsterdam
     address <MyIPv6 tunnel endpont>
     netmask  64
     ttl 255
     up ip -6 route add default dev he-ipv6
     down ip -6 route del default dev he-ipv6

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