[Users] Multi-homed, dual stack (ip4/ip6) Debian - Network Issues

Kir Kolyshkin kir at openvz.org
Tue Mar 4 20:16:30 PST 2014 

In general, network related issues are not among the easiest to reply 
to, because
unless this is something very obvious, it requires some considerable 
time to understand
the specifics of the setup, and no one has that time. Me included.

As much as I wish to help, I think the best way for you is to get an 
OpenVZ support contract.
That way you'll have engineers who deal with such stuff on a daily 
basis, and they will surely
be able to help (or find a bug and forward it to developers). It's here:

http://www.parallels.com/support/virtualization-suite/openvz/

PS please understand I don't want to sell anything, I just want to help.

On 02/26/2014 08:50 PM, Axton wrote:
> A little more information to add.
>
> *_I rebooted the server, which resulted in the state where I cannot 
> reach ipv6 devices on the other side of my router:_*
> *root at cluster-02:~# ping6 google.com <http://google.com>*
> PING google.com <http://google.com>(atl14s08-in-x09.1e100.net 
> <http://atl14s08-in-x09.1e100.net>) 56 data bytes
> ping: sendmsg: Network is down
> ping: sendmsg: Network is down
> ^C
> --- google.com <http://google.com> ping statistics ---
> 2 packets transmitted, 0 received, 100% packet loss, time 999ms
>
>
> *_Here is the route and neighborhood information while in this broken 
> state:_*
> *root at cluster-02:~# ip -6 route*
> 2001:xyz:abc:40::/64 dev vmbr40  proto kernel  metric 256  expires 
> 2147157sec mtu 1500 advmss 1440 hoplimit 0
> fe80::1 dev venet0  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev vmbr30  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev vmbr40  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1.40  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1.30  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev venet0  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev veth10000.40  proto kernel  metric 256  mtu 1500 advmss 
> 1440 hoplimit 0
> fe80::/64 dev veth10000.30  proto kernel  metric 256  mtu 1500 advmss 
> 1440 hoplimit 0
> default via fe80::225:90ff:fe09:9b81 dev vmbr40  proto kernel  metric 
> 1024  expires 11sec mtu 1500 advmss 1440 hoplimit 64
> *root at cluster-02:~# ip -6 neigh*
> fe80::225:90ff:fe09:9b81 dev vmbr30 lladdr 00:25:90:09:9b:81 router STALE
> 2001:xyz:abc:40::10 dev vmbr40 lladdr 00:25:90:09:9b:81 router REACHABLE
>
>
> *_Just to reconfirm things are not working after print the 
> route/neighborhood information:_*
> *root at cluster-02:~# ping6 google.com <http://google.com>*
> PING google.com <http://google.com>(atl14s08-in-x09.1e100.net 
> <http://atl14s08-in-x09.1e100.net>) 56 data bytes
> ping: sendmsg: Network is down
> ping: sendmsg: Network is down
> ^C
> --- google.com <http://google.com> ping statistics ---
> 2 packets transmitted, 0 received, 100% packet loss, time 999ms
>
>
> *_I delete the default ipv6 route:_*
> *root at cluster-02:~# ip -6 route del default via 
> fe80::225:90ff:fe09:9b81 dev vmbr40*
> *
> *
> *
> *
> *_Still unreachable:_*
> *root at cluster-02:~# ping6 google.com <http://google.com>*
> connect: Network is unreachable
>
>
> *_Here is the route and neighborhood information after using ip to 
> delete the route:_*
> *root at cluster-02:~# ip -6 route*
> 2001:xyz:abc:40::/64 dev vmbr40  proto kernel  metric 256  expires 
> 2147157sec mtu 1500 advmss 1440 hoplimit 0
> fe80::1 dev venet0  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev vmbr30  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev vmbr40  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1.40  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1.30  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev venet0  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev veth10000.40  proto kernel  metric 256  mtu 1500 advmss 
> 1440 hoplimit 0
> fe80::/64 dev veth10000.30  proto kernel  metric 256  mtu 1500 advmss 
> 1440 hoplimit 0
> default via fe80::225:90ff:fe09:9b81 dev vmbr40  proto kernel  metric 
> 1024  expires 10sec mtu 1500 advmss 1440 hoplimit 64
> *root at cluster-02:~# ip -6 neigh*
> fe80::225:90ff:fe09:9b81 dev vmbr30 lladdr 00:25:90:09:9b:81 router STALE
> 2001:xyz:abc:40::10 dev vmbr40 lladdr 00:25:90:09:9b:81 router STALE
> fe80::225:90ff:fe09:9b81 dev vmbr40 lladdr 00:25:90:09:9b:81 router STALE
>
>
> *_I then attempt to re-add the route (though it does not show to have 
> been deleted):_*
> *root at cluster-02:~# ip -6 route add default via 
> fe80::225:90ff:fe09:9b81 dev vmbr40*
> RTNETLINK answers: File exists
>
>
> *_I now attempt to access the machine on the other side of my router 
> and things work:_*
> *root at cluster-02:~# ping6 google.com <http://google.com>*
> PING google.com <http://google.com>(atl14s08-in-x01.1e100.net 
> <http://atl14s08-in-x01.1e100.net>) 56 data bytes
> 64 bytes from atl14s08-in-x01.1e100.net 
> <http://atl14s08-in-x01.1e100.net>: icmp_seq=1 ttl=57 time=59.7 ms
> 64 bytes from atl14s08-in-x01.1e100.net 
> <http://atl14s08-in-x01.1e100.net>: icmp_seq=2 ttl=57 time=61.1 ms
> ^C
> --- google.com <http://google.com> ping statistics ---
> 2 packets transmitted, 2 received, 0% packet loss, time 1000ms
> rtt min/avg/max/mdev = 59.782/60.448/61.114/0.666 ms
>
>
> *_Here is the route and neighborhood information after the changes 
> above:_*
> *root at cluster-02:~# ip -6 neigh*
> 2001:xyz:abc:40::10 dev vmbr40 lladdr 00:25:90:09:9b:81 router REACHABLE
> fe80::225:90ff:fe09:9b81 dev vmbr30 lladdr 00:25:90:09:9b:81 router STALE
> fe80::225:90ff:fe09:9b81 dev vmbr40 lladdr 00:25:90:09:9b:81 router 
> REACHABLE
> *root at cluster-02:~# ip -6 route*
> 2001:xyz:abc:40::/64 dev vmbr40  proto kernel  metric 256  expires 
> 2147157sec mtu 1500 advmss 1440 hoplimit 0
> fe80::1 dev venet0  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev vmbr30  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev vmbr40  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1.40  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev eth1.30  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev venet0  proto kernel  metric 256  mtu 1500 advmss 1440 
> hoplimit 0
> fe80::/64 dev veth10000.40  proto kernel  metric 256  mtu 1500 advmss 
> 1440 hoplimit 0
> fe80::/64 dev veth10000.30  proto kernel  metric 256  mtu 1500 advmss 
> 1440 hoplimit 0
> default via fe80::225:90ff:fe09:9b81 dev vmbr40  proto kernel  metric 
> 1024  mtu 1500 advmss 1440 hoplimit 64
>
>
> On Wed, Feb 26, 2014 at 12:05 AM, Axton <axton.grams at gmail.com 
> <mailto:axton.grams at gmail.com>> wrote:
>
>     *Synopsis: *Servers are connected to a series of vlans.  When
>     server boots with vz enabled in the inittab, the HN cannot reach
>     routed ipv6 hosts.  VEs can reach routed ipv6 hosts.
>
>     I have tried to narrow down the cause of the issue to the extent
>     that I can, so the information presented below uses the fewest
>     variables required to illustrate the issues I see.   In practice,
>     these servers are connected to more than two vlans and there are
>     many CT's on each HE, which have different combinations of vlan
>     access.  For the purposes of this conversation I am only
>     referencing 2 vlans since I can consistently reproduce the issue
>     with just 2 vlans.
>
>
> snipped
>
>     Any help is appreciated.
>
>     Thanks,
>     Axton Grams
>
>
>
>
> _______________________________________________
> Users mailing list
> Users at openvz.org
> https://lists.openvz.org/mailman/listinfo/users

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