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Connection problems from host to inet via ipv6

Shadow Hawkins on Monday, 26 April 2010 11:24:49

I have a quite odd problem with my ipv6 setup. I don't know exactly it stared to behave like this, but for whatever reason I can't use ipv6 for external connections until I ping the host in the network from the router. Now a bit more detailed description. The network looks something like this:

+-------+ +--->| Host1 | | +-------+ | +--------+ | +-------+ | Router |<----+--->| Host2 | +--------+ | +-------+ | . . . . . . | | +-------+ +--->| HostN | +-------+

Now. I can ping6 any of the hosts from Host1 but not the router. Same for any of the other hosts. So: Host1->Host2 works Host1->Router fails Host2->HostN works Host2->Host1 works HostN->Router fails For the failed ones I get Destination unreachable: Address unreachable But if I ping6 from Router to Host1 then I can ping6 back from Host1 to Router and use ipv6 for other stuff. At the same time Host2 or any other still doesn't ping6 Router. So I have to ping6 from Router to any of the hosts to make them able to use ipv6 for internet traffic. That was everything is ok till one of the host reboots. After that I have to ping6 it from the Router again to make it work. Some data from Router and Host1: Router before ping6 to Host1

ip -6 addr show dev eth1 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000 inet6 2001:15c0:668f:1::1/64 scope global valid_lft forever preferred_lft forever inet6 fe80::207:e9ff:fe00:c9dc/64 scope link valid_lft forever preferred_lft forever ip -6 route show dev eth1 2001:15c0:668f:1::/64 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0 fe80::/64 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0 ff00::/8 metric 256 mtu 1500 advmss 1440 hoplimit 0 ip -6 neigh show <empty>

Router after ping6 to Host1

ping6 2001:15c0:668f:1::3 PING 2001:15c0:668f:1::3(2001:15c0:668f:1::3) 56 data bytes 64 bytes from 2001:15c0:668f:1::3: icmp_seq=1 ttl=64 time=0.722 ms 64 bytes from 2001:15c0:668f:1::3: icmp_seq=2 ttl=64 time=0.169 ms ip -6 neigh show 2001:15c0:668f:1::3 dev eth1 lladdr 00:16:e6:85:e9:47 STALE fe80::216:e6ff:fe85:e947 dev eth1 lladdr 00:16:e6:85:e9:47 STALE ip -6 addr show dev eth1 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000 inet6 2001:15c0:668f:1::1/64 scope global valid_lft forever preferred_lft forever inet6 fe80::207:e9ff:fe00:c9dc/64 scope link valid_lft forever preferred_lft forever ip -6 route show dev eth1 2001:15c0:668f:1::/64 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0 fe80::/64 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0 ff00::/8 metric 256 mtu 1500 advmss 1440 hoplimit 0 Host1 before ping6 from Router ip -6 addr show dev eth0 3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000 inet6 2001:15c0:668f:1::3/64 scope global valid_lft forever preferred_lft forever inet6 fe80::216:e6ff:fe85:e947/64 scope link valid_lft forever preferred_lft forever ip -6 route show dev eth0 2001:15c0:668f:1::/64 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 ff00::/8 metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 default via 2001:15c0:668f:1::1 metric 20 mtu 1500 advmss 1440 hoplimit 4294967295 ping6 2001:15c0:668f:1::1 PING 2001:15c0:668f:1::1(2001:15c0:668f:1::1) 56 data bytes From 2001:15c0:668f:1::3 icmp_seq=1 Destination unreachable: Address unreachable From 2001:15c0:668f:1::3 icmp_seq=2 Destination unreachable: Address unreachable ip -6 neigh show 2001:15c0:668f:1::1 dev eth0 FAILED Host1 after ping6 from Router ip -6 addr show dev eth0 3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000 inet6 2001:15c0:668f:1::3/64 scope global valid_lft forever preferred_lft forever inet6 fe80::216:e6ff:fe85:e947/64 scope link valid_lft forever preferred_lft forever ip -6 route show dev eth0 2001:15c0:668f:1::/64 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 ff00::/8 metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 default via 2001:15c0:668f:1::1 metric 20 mtu 1500 advmss 1440 hoplimit 4294967295 ping6 2001:15c0:668f:1::1 PING 2001:15c0:668f:1::1(2001:15c0:668f:1::1) 56 data bytes 64 bytes from 2001:15c0:668f:1::1: icmp_seq=1 ttl=64 time=1.14 ms 64 bytes from 2001:15c0:668f:1::1: icmp_seq=2 ttl=64 time=0.162 ms ip -6 neigh show 2001:15c0:668f:1::1 dev eth0 lladdr 00:07:e9:00:c9:dc router STALE

Anyone has an idea what could be the problem? And if you need more data just ask for it.

Connection problems from host to inet via ipv6

Shadow Hawkins on Sunday, 25 April 2010 13:59:25

Meh, looks like the board managed to break the drawing a bit... sohere a link to the picture http://img717.imageshack.us/img717/4021/omrezjev.png

Connection problems from host to inet via ipv6

Jeroen Massar SixXS Staff

on Monday, 26 April 2010 11:28:19

Use the [ code ] blocks as indicated on the right. Fixed that for you.

Connection problems from host to inet via ipv6

Jeroen Massar SixXS Staff

on Monday, 26 April 2010 11:27:54

Anyone has an idea what could be the problem? And if you need more data just

ask for it.

You most very likely have a multicast issue either in one of the hosts or your router or in the network equipment in between. Sometimes putting equipment in promisc helps there, but that is avoiding the issue. What (switch?) is connecting your hosts and the router? If it has a 'IGMP snooping' or other such multicast options, try disabling/toggling it.

Connection problems from host to inet via ipv6

Shadow Hawkins on Monday, 26 April 2010 21:50:40

The switch connecting them is a Netgear GS108. So it shouldn't be a problem with it. Will try tomorrow since I will have tim to get some tcpdumps and post them if that will help. But since I will have time go over the whole ipv6 setup on the network too see if I will find any error in it.

Connection problems from host to inet via ipv6

Shadow Hawkins on Wednesday, 28 April 2010 18:12:51

So, I managed to figure out what the problem was/is (I think). Jeroen, as you wrote that it could be a multicast issue you were right. It was on the router side since as it looks like the in kernel driver for the NIC (r8169) has some multicast problems what I was sure was fixed in one the of the 2.6.2x kernels. Installed the driver from Realtek and now it works. So, thanks for the help.

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