After I ran upgrade to CentOS 6.6, the ipv6 connectivity breaks down after a period of about 5 minutes. When I initate ping to another host in the same subnet, communication to and from that host is possible again for a few minutes and then breaks down again.<br />
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Configuration:<br />
# brctl show<br />
bridge name bridge id STP enabled interfaces<br />
br0 8000.6c626dcf364b no eth0<br />
<br />
# ifconfig br0<br />
br0 Link encap:Ethernet HWaddr 6C:62:6D:CF:36:4B<br />
inet addr:192.168.0.66 Bcast:192.168.0.255 Mask:255.255.255.0<br />
inet6 addr: 2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b/64 Scope:Global<br />
inet6 addr: fe80::6e62:6dff:fecf:364b/64 Scope:Link<br />
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When I boot the machine, it obtains an ipv6 prefix from the network routing advertisor and sets up an IP address. ipv6 connectivity on this address works for several minutes, but then suddenly stops working. The ipv6 address is no longer pingable from another machine within the same network:<br />
<br />
veriton$ ping6 2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b<br />
PING 2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b(2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b) 56 data bytes<br />
^C<br />
--- 2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b ping statistics ---<br />
3 packets transmitted, 0 received, 100% packet loss, time 2016ms<br />
<br />
Same when I try to ping the link-local address with fe80::6e62:6dff:fecf:364b%eth0<br />
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However, when I initiate a ping6 from my CentOS machine to the remote machine within the same network:<br />
<br />
# ping6 veriton<br />
PING veriton(2001:XXXX:XXXX:XXXX::2) 56 data bytes<br />
64 bytes from 2001:XXXX:XXXX:XXXX::2: icmp_seq=1 ttl=64 time=1.22 m<br />
<br />
it works. and by then, also reverse-ping works again (of course), but only for several minutes:<br />
<br />
veriton$ ping6 2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b<br />
PING 2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b(2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b) 56 data bytes<br />
64 bytes from 2001:XXXX:XXXX:XXXX:6e62:6dff:fecf:364b: icmp_seq=1 ttl=255 time=1.25 ms<br />
<br />
Because the default route is advertised as a link-local address and return path will be the global ipv6 address, so also all outgoing connections will stuck within a few minutes.<br />
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I have connected devices with several different physical paths and switches, so problems in network hardware can be eliminated.<br />
<br />
When I reboot back to kernel 2.6.32-431.29.2.el6 the problems are gone.
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