How to implement the multihop VPN?

Hi guys
I want get a multihop VPN by OPENWRT, currently I set it to work for single using strongSwan and xl2tpd and L2TP/IPSec protocol, it's work fine all. Then I wanna throught the package from VPN1(ppp0) to VPN2(ppp1).
anybody have the good ideas?

the interface list was below:

eth0.2    Link encap:Ethernet  HWaddr F0:B4:29:71:71:B0
          inet addr:192.168.2.151  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::f2b4:29ff:fe71:71b0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:75300 errors:0 dropped:0 overruns:0 frame:0
          TX packets:61454 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:28563603 (27.2 MiB)  TX bytes:13016694 (12.4 MiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:159 errors:0 dropped:0 overruns:0 frame:0
          TX packets:159 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1
          RX bytes:13604 (13.2 KiB)  TX bytes:13604 (13.2 KiB)

ppp0      Link encap:Point-to-Point Protocol
          inet addr:10.20.0.24  P-t-P:1.0.0.1  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:35984 errors:0 dropped:0 overruns:0 frame:0
          TX packets:44892 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:21072150 (20.0 MiB)  TX bytes:6357224 (6.0 MiB)

ppp1      Link encap:Point-to-Point Protocol
          inet addr:10.20.0.10  P-t-P:1.0.0.1  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:3 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:30 (30.0 B)  TX bytes:30 (30.0 B)

and the route table was below:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         1dot1dot1dot1.c 0.0.0.0         UG    0      0        0 ppp0
1.0.0.1         *               255.255.255.255 UH    0      0        0 ppp0
1.0.0.1         *               255.255.255.255 UH    0      0        0 ppp1
108.59.8.41     192.168.2.1     255.255.255.255 UGH   0      0        0 eth0.2
151.236.34.170  192.168.2.1     255.255.255.255 UGH   0      0        0 eth0.2
192.168.1.0     *               255.255.255.0   U     0      0        0 br-lan
192.168.2.0     *               255.255.255.0   U     0      0        0 eth0.2
192.168.2.1     *               255.255.255.255 UH    0      0        0 eth0.2

and the firmwall rule:

iptables -A forwarding_rule -i ppp0 -o br-lan -j ACCEPT
iptables -A forwarding_rule -i br-lan -o ppp0 -j ACCEPT

iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -o ppp0 -j MASQUERADE

Does resolve it via iptables NAT forward´╝č