Server didn't become ssh-able!

[changzhi]

Error occurs When I install Ironic in devstack. The console display:
2015-12-01 09:07:04.821 | ++ ironic_ssh_check /opt/stack/data/ironic/ssh_keys/ironic_key 10.250.11.127 22 stack 15
2015-12-01 09:07:04.821 | ++ local key_file=/opt/stack/data/ironic/ssh_keys/ironic_key
2015-12-01 09:07:04.821 | ++ local floating_ip=10.250.11.127
2015-12-01 09:07:04.821 | ++ local port=22
2015-12-01 09:07:04.821 | ++ local default_instance_user=stack
2015-12-01 09:07:04.821 | ++ local active_timeout=15
2015-12-01 09:07:04.821 | ++ timeout 15 sh -c 'while ! ssh -p 22 -o StrictHostKeyChecking=no -i /opt/stack/data/ironic/ssh_keys/ironic_key stack@10.250.11.127 echo success; do sleep 1; done'
2015-12-01 09:07:19.825 | ++ die 725 'server didn'\''t become ssh-able!'
2015-12-01 09:07:19.825 | ++ local exitcode=0
2015-12-01 09:07:19.825 | [Call Trace]
2015-12-01 09:07:19.825 | ./stack.sh:1325:run_phase
2015-12-01 09:07:19.825 | /opt/stack/devstack/functions-common:1746:source
2015-12-01 09:07:19.825 | /opt/stack/devstack/extras.d/50-ironic.sh:29:prepare_baremetal_basic_ops
2015-12-01 09:07:19.825 | /opt/stack/devstack/lib/ironic:816:configure_ironic_auxiliary
2015-12-01 09:07:19.825 | /opt/stack/devstack/lib/ironic:731:ironic_ssh_check
2015-12-01 09:07:19.825 | /opt/stack/devstack/lib/ironic:725:die
2015-12-01 09:07:19.829 | [ERROR] /opt/stack/devstack/lib/ironic:725 server didn't become ssh-able!
2015-12-01 09:07:20.834 | Error on exit

And my local.conf is http://paste.openstack.org/show/480462/

Did anyone meet the same error as me?

[changzhi (changzhi)]

Set IRONIC_SSH_TIMEOUT=10 in local.conf and rerun stack.sh can resolve this problem.