PPP can be encapsulated over Ethernet and it can be used to offer authentication over Ethernet connections. It cannot be used for Multilinking Ethernet connections. When using PPPoE we need a server and a client.
Server Side
Configuring the server makes use of the Virtual Template/Virtual Access interfaces. We configure the Virtual Template interface, but the Virtual Access interface will be up/up in the process. Its configuration will be taken from the Vitual Template interface.
First define the Virtual Template that will hold the PPP configuration:
R1(config)# int VIRTUAL-TEMPLATE-INT
R1(config-if)# ip address IP-ADDR NETMASK
! define IP assignment for clients:
R1(config-if)# peer default ip address {CLIENT-IP | pool [IP-POOL]| dhcp-pool [DHCP-POOL] |dhcp}
See PPP 101 for details about client IP assignment.
Then, configure the Broadband Access Group that points to the Virtual-Template interface:
The last step is to enable PPPoE on the physical interface and assign it to the BBA-Group:
R1(config)# interface FAST-ETHERNET-INT
R1(config-if)# pppoe enable group {GROUP|default}
Client Side
On the client side, we have to make use of Dialer Interfaces. Dialer Interfaces will look for a physical interface available in their Dialer Pool before initiating connections
R2(config)# interface DIALER1
! By default Dialer interfaces have encapsulation set to HDLC.
R2(config-if)# encapsulation ppp
!Get the IP address from the server
R2(config-if)# ip address {negotiated|IP-ADDR NETMASK}
R2(config-if)# dialer-pool POOL-ID
! What pool shoud I use?
Physical interfaces are assigned to Dialer Pools:
R2(config)# interface FASTETHERNET0
! Link the Ethernet Interface to the Dialer interface via the dial-pool.
R2(config-if)# pppoe-client dial-pool-number POOL-ID
! What pool am I a member of?
R2(config-if)# no shut
R2(config-if)# end
Additional information about Dialer Interfaces, can be found here.
After a little while we will see the assigned IP address on the interface and the PPP /32 ip route:
R2#sh ip route
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Dialer1
99.0.0.0/32 is subnetted, 1 subnets
C 99.0.0.10 is directly connected, Dialer1
R2#sh ip int brie
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES unset up up
FastEthernet0/1 unassigned YES unset administratively down down
Virtual-Access1 unassigned YES unset up up
Dialer1 99.0.0.10 YES IPCP up up
R2#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/24/52 ms
R2#
If we want to enable authentication, just configure the PPP interfaces on each device, that is the Virtual-Template on the Server and the Dialer interface on the Client.
