i have already l2tpv3 tunnel between 2 routers :
l2tp-class l2tpv3.class
authentication
digest secret 7 0701234D4A2A363732010E0F162F3F hash SHA1
password 7 082F4E4F0D3A2A25370A1910223B253B20222D0103
receive-window 100
retransmit retries 10
pseudowire-class cisco-class
encapsulation l2tpv3
interworking ip
protocol l2tpv3 l2tpv3.class
ip local interface Loopback0
ip pmtu
interface Loopback0
ip address 192.168.254.252 255.255.255.255
interface FastEthernet0/2.70
encapsulation dot1Q 70
xconnect 192.168.254.244 1020 pw-class cisco-class
my question is that i am going to setup GRE/IPSEC between the 2 routers , but the 2 loopback interfaces of the lt2pv3 tunnel will be routable through the GRE/IPsec tunnel , is this optimum solution & will it work , or there is a nother solution to secure the l2tp " l2tp/ipsec)