Cisco CCNP and CCIE Study Notes

I thought I knew multilink PPP well but in looking into the feature this morning, I realized that I had never configured it for serial interfaces; I had always used it in the past with ISDN or in the context of async dial-up. When I tried to see how I could exploit multilink PPP with synchronous serial interfaces, I realized that I didn't know how to configure the bundle interface. I fooled around with virtual-template and virtual-access interfaces for the MPPP bundle interface and then finally had to research the web and find out about the multilink virtual interface that had to be used. There is always more to learn even regarding topics you think you know well!

So, with two routers connected back-to-back via a pair of serial interfaces, I brought up multilink PPP with the following config

Router1

interface Multilink1
 ip address 10.10.10.1 255.255.255.0
 ppp multilink
 ppp multilink group 1
!     
interface Serial2
 no ip address
 encapsulation ppp
 ppp multilink
 ppp multilink group 1
!     
interface Serial3
 no ip address
 encapsulation ppp
 ppp multilink
 ppp multilink group 1

interface Multilink1
 ip address 10.10.10.2 255.255.255.0
 ppp multilink
 ppp multilink group 1
!     
interface Serial2
 no ip address
 encapsulation ppp
 ppp multilink
 ppp multilink group 1
!
interface Serial3
 no ip address
 encapsulation ppp
 ppp multilink
 ppp multilink group 1

Of course this is very basic config and one could add on PPP authentication and a host of multilink features to this as needed.