Cisco WAN :: 2821 - Configure Router To Use 2 ADSL Lines With Dialer And Modem In RFC2684 Mode?

I want to configure my router to use 2 ADSL lines each with a dialer and a modem in RFC2684 mode. I have a 2821 (IOS 12.4) with an HWIC-4ESW.
 
My network topology is like this :

ADSL Modem 1 (RFC2684) --
(Fa0/0/0)
Router -- (Gi0/1) MyLAN
(Fa0/0/1)
ADSL Modem 2 (RFC2684) --/
 
1. I configure my DSL Modem in RFC 2684. The first use 172.16.0.2/29 and the second 172.16.0.3/29. I connect this devices to Fa0/0/0 and Fa0/0/1.
 
2. I configure Vlan1 to use the network configured on my modem :

interface Vlan1
ip address 172.16.0.1 255.255.255.248
 
3. I try to ping my devices :

#ping 172.16.0.2
 Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.0.3, timeout is 2 seconds:
!!!!!

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