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

Wed Feb 26 20:50:24 PST 2014

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(atl14s08-in-x09.1e100.net) 56 data bytes
ping: sendmsg: Network is down
ping: sendmsg: Network is down
^C
--- 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(atl14s08-in-x09.1e100.net) 56 data bytes
ping: sendmsg: Network is down
ping: sendmsg: Network is down
^C
--- 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(atl14s08-in-x01.1e100.net) 56 data bytes
64 bytes from atl14s08-in-x01.1e100.net: icmp_seq=1 ttl=57 time=59.7 ms
64 bytes from atl14s08-in-x01.1e100.net: icmp_seq=2 ttl=57 time=61.1 ms
^C
--- 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> 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
>
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