Thanks venkata anil.
@Paul. I checked the status of strongswan status and rhel strongswan status(using my patch set). Seems they have almost the same output. 

Ubuntu(not established status):
Command: ['ip', 'netns', 'exec', u'qrouter-9194e4c5-4f45-445f-b32c-c1101f4c215b', 'neutron-vpn-netns-wrapper', u'--mount_paths=/etc:/opt/stack/data/neutron/ipsec/9194e4c5-4f45-445f-b32c-c1101f4c215b/etc,/var/run:/opt/stack/data/neutron/ipsec/9194e4c5-4f45-445f-b32c-c1101f4c215b/var/run', '--cmd=ipsec,status']
Exit code: 0
Stdin:
Stdout: Command: ['mount', '--bind', '/opt/stack/data/neutron/ipsec/9194e4c5-4f45-445f-b32c-c1101f4c215b/etc', '/etc'] Exit code: 0 Stdout:  Stderr: Command: ['mount', '--bind', '/opt/stack/data/neutron/ipsec/9194e4c5-4f45-445f-b32c-c1101f4c215b/var/run', '/var/run'] Exit code: 0 Stdout:  Stderr: Command: ['ipsec', 'status'] Exit code: 0 Stdout: Routed Connections:
ed765a9b-a008-4f3b-96ec-74eea7576ea1{1}:  ROUTED, TUNNEL
ed765a9b-a008-4f3b-96ec-74eea7576ea1{1}:   10.0.0.0/24 === 10.2.0.0/24
Security Associations (0 up, 0 connecting):
  none
 Stderr:


RHEL(not establish status output)
[root@icm ~]# /usr/bin/python /usr/bin/neutron-rootwrap /etc/neutron/rootwrap.conf ip netns exec qrouter-9f798b40-d2b8-4ed2-b060-707947941db4 neutron-vpn-netns-wrapper --mount_paths=/etc:/var/lib/neutron/ipsec/9f798b40-d2b8-4ed2-b060-707947941db4/etc,/var/run:/var/lib/neutron/ipsec/9f798b40-d2b8-4ed2-b060-707947941db4/var/run --cmd=strongswan,status
Command: ['mount', '--bind', '/var/lib/neutron/ipsec/9f798b40-d2b8-4ed2-b060-707947941db4/etc', '/etc'] Exit code: 0 Stdout:  Stderr: Command: ['mount', '--bind', '/var/lib/neutron/ipsec/9f798b40-d2b8-4ed2-b060-707947941db4/var/run', '/var/run'] Exit code: 0 Stdout:  Stderr: Command: ['strongswan', 'status'] Exit code: 0 Stdout: Routed Connections:
33791325-3bb0-4848-94cb-947c1d002668{4}:  ROUTED, TUNNEL
33791325-3bb0-4848-94cb-947c1d002668{4}:   10.6.100.0/24 === 192.168.100.0/24 
Security Associations (0 up, 0 connecting):
  none
 Stderr: 

RHEL(established):
[root@icm ~]# /usr/bin/python /usr/bin/neutron-rootwrap /etc/neutron/rootwrap.conf ip netns exec qrouter-9f798b40-d2b8-4ed2-b060-707947941db4 neutron-vpn-netns-wrapper --mount_paths=/etc:/var/lib/neutron/ipsec/9f798b40-d2b8-4ed2-b060-707947941db4/etc,/var/run:/var/lib/neutron/ipsec/9f798b40-d2b8-4ed2-b060-707947941db4/var/run --cmd=strongswan,status
Command: ['mount', '--bind', '/var/lib/neutron/ipsec/9f798b40-d2b8-4ed2-b060-707947941db4/etc', '/etc'] Exit code: 0 Stdout:  Stderr: Command: ['mount', '--bind', '/var/lib/neutron/ipsec/9f798b40-d2b8-4ed2-b060-707947941db4/var/run', '/var/run'] Exit code: 0 Stdout:  Stderr: Command: ['strongswan', 'status'] Exit code: 0 Stdout: Routed Connections:
d1a377d6-d796-4727-8825-4f5b89b5e483{2}:  ROUTED, TUNNEL
d1a377d6-d796-4727-8825-4f5b89b5e483{2}:   10.6.100.0/24 === 192.168.100.0/24 
Security Associations (1 up, 0 connecting):
d1a377d6-d796-4727-8825-4f5b89b5e483[1]: ESTABLISHED 34 seconds ago, 10.105.0.236[10.105.0.236]...10.105.0.163[10.105.0.163]
d1a377d6-d796-4727-8825-4f5b89b5e483{2}:  INSTALLED, TUNNEL, ESP SPIs: cc17e56a_i c08d390c_o
d1a377d6-d796-4727-8825-4f5b89b5e483{2}:   10.6.100.0/24 === 192.168.100.0/24 
 Stderr: