Target:

we config the R5 to dial pppoe to R1, and gain the IP address.

top

                                                            R5
                                                              |
                                                              |(PPPOE)
                         PC-----------------------R1-------------------R2
                                                               |                    |
                                                               |                   (×××)
                                                               |                    |
                                                               |           
                                                              R3------------------R4
pppoe(PC-R1)    ------ 10.1.1.0/24------

PPTP(PC-R2)     ------------------192.168.1.0/24--------------

configuration

R5

interface Dialer1
 ip address dhcp
 encapsulation ppp
 dialer pool 1
 dialer-group 1
 ppp authentication pap callin
 ppp pap sent-username xxx password 0 xxx

vpdn enable
vpdn ip udp ignore checksum
!
vpdn-group adsl
 request-dialin
  protocol pppoe
interface FastEthernet0/0
 pppoe enable
 pppoe-client dial-pool-number 1