1. TROUBLE DESCRIPTION
1.1. Trouble summary
To ping6 across VMs , ipv6 stateful mode subnet need to be added to the router or else ping6 will fail
since MAC addreess getting resolved only adding  to the router. Looks like design need to be change
 ostinato@ostinato:~$ ifconfig
ens3      Link encap:Ethernet  HWaddr fa:16:3e:fa:22:9c  
          inet addr:10.10.10.8  Bcast:10.10.10.255  Mask:255.255.255.0
          inet6 addr: 2001:db8:aaaa::f/128 Scope:Global
          inet6 addr: fe80::f816:3eff:fefa:229c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:9000  Metric:1
          RX packets:13341 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13350 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1169148 (1.1 MB)  TX bytes:1169279 (1.1 MB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:160 errors:0 dropped:0 overruns:0 frame:0
          TX packets:160 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1
          RX bytes:11840 (11.8 KB)  TX bytes:11840 (11.8 KB)

ostinato@ostinato:~$ ping6 2001:db8:aaaa::a
PING 2001:db8:aaaa::a(2001:db8:aaaa::a) 56 data bytes
64 bytes from 2001:db8:aaaa::a: icmp_seq=1 ttl=64 time=0.411 ms
64 bytes from 2001:db8:aaaa::a: icmp_seq=2 ttl=64 time=0.280 ms
^C

1.3. Frequency of fault
Seen multiple times

1.4. Workaround and Recovery
Need to add to the router

1.5. System impact

ipv6 stateful mode is not working as expected

1.6. Known problem within the OpenStack community?
NA

2. Configuration data
2.1. HW Configuration details
EBS, HP or DELL:
Number of subracks:
Number of blades:
EMC (Yes or No):
Switches used (X670V, X770 or BD):

2.2. SW Configuration details
CEE-  CEE8RC2
CSC - 19.1.1.0-269
CSS -2.8.2.css5.R2C