Unable to communicate with other servers with the same IPv6 prefix
Environment
- Red Hat Enterprise Linux 6.4
- IPv6
Issue
- ping (ping6) to other servers with the same IPv6 prefix fails
- This problem started after the following message was observed in the messages file
server01 ntpd[2161]: Deleting interface #11 eth1, 2002:4403:0:0:250:56ff:fef3:4263#123, interface stats: received=0, sent=0, dropped=0, active_time=2592679 secs
Resolution
- Bring the local interface down and back up again
or - Add the route to the local prefix back in manually
ip -6 route add 2002:4403::/64 proto kernel metric 256 dev eth1
Root Cause
If an auto-configured address is created after the static address with the same prefix and then the auto-configured address's life time expires and the address is removed the prefix route is also deleted. Bugzilla 1130235 has been added to address this issue.
Diagnostic Steps
- network trace shows no neighbour solicitation messages for the other server
- network trace shows that the ICMPv6 echo packet was sent to the default router's MAC address
- The routing table showed only 1 route to the static address on the target prefix over the lo device
grep 20024403 /proc/net/ipv6_route
20024403000000000000000000000200 80 00000000000000000000000000000000 00 00000000000000000000000000000000 00000000 00000001 00000000 80200001 lo
[root@ThinkStation ~]#
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