IPV6_Service:Ipv6 address assignment to VMs takes almost 40 to 60 secs from ODL controller

1.Create network
2.Crate ipv6 subnet and attach the subnet to router
neutron subnet-create net1 2001:db8:cafe::/64 --ip-version 6 --ipv6-ra-mode slaac --ipv6-address-mode slaac --name ipv6s1
neutron router-interface-add R1 ipv6s1
Added interface 2069a6ff-3310-4fb8-afd4-c0760a006bcf to router R1.
3.Boot CSS VM
4.login to VM
5.ifconfig <interface (eth0)> down
6.sudo ifconfig eth0 up

neutron port update is sending as null port id due this issue.Its waiting for the RA mutlicast packets to get assign the ipv6 address from the ODL.

This is reason why its taking long duration to get assigned ipv6 address to VM.