Configure GRE tunnel to start on reboot?

I’m trying to configure GRE tunnel (between 2 VBOX ubuntu server 12.04 LTS on win 7 host) but it keep failed.

The configuration in /etc/network/interfaces

# VBOX A
ip address 172.168.1.1 /24
ip tunnel 10.0.201.1 /24

# VBOX A
iptunnel add tunX mode gre remote 172.168.1.1 local 172.168.2.1 ttl 225
ifconfig tunX 10.0.201.1/24
ifconfig tunX up
ifconfig tunX pointopoint 10.0.201.2
ifconfig tunX multicast

# VBOX B
ip address 172.168.2.1 /24
ip tunnel 10.0.201.2 /24

seting tunnel di VBOX B
iptunnel add tunY mode gre local 172.168.2.1 remote 172.168.1.1 ttl 225
ifconfig tunY 10.0.201.2/24
ifconfig tunY up
ifconfig tunY pointopoint 10.0.201.1
ifconfig tunY multicast  

But ifconfig shows the tunnel is up

Are there any other way to configure the GRE tunnel to start on reboot beside /etc/network/interfaces configuration???