Configuring Multilink PPP using multiple E1/T1

In networking, the Point-to-Point Protocol, or PPP, is a data link protocol commonly used to establish a direct connection between two networking nodes. It can provide connection authentication, transmission encryption privacy, and compression.

MLPPP aggregates multiple physical links into a single logical bundle. More specifically, MLPPP bundles multiple link-layer channels into a single network-layer channel. Peers negotiate MLPPP during the initial phase of Link Control Protocol (LCP) option negotiation. Each system indicates that it is  multilink-capable by sending the multilink option as part of its initial LCP configuration request.

Insert the E1/T1 WIC into router. Router config will be showing such like statement:

card type command needed for slot/vwic-slot 0/0

Means you have a T1/E1 VWIC for which you did not specify whether you want to use the T1 or E1 functionality. This is done via the card-type command:

card type e1 0 0

This example assumes that you want to use the E1 functionality of the VWIC in slot 0/0.
Now configure the E1 as under:

!
controller E1 0/0/0
framing NO-CRC4
channel-group 0 timeslots 1-31
!
controller E1 0/0/1
framing NO-CRC4
channel-group 0 timeslots 1-31
!

network-clock-participate wic 0  ----->for sync clock, on both links

!

Now to bundle a couple of E1s configure a Multilink interface as under:
[Router 1]

!
interface Multilink1
ip address 192.168.100.1 255.255.255.252 ----> Assigning IP address to interface.
ppp multilink
ppp multilink group 1
!

Next define ppp encapsulation on E1 serial interfaces. Note that the Serial interfaces are assigned to a Multilink group. The Serial Interfaces have no ip address. The Multilink interface has ip address that is for the Multilink group.

!

interface Serial0/0/0:0

no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1
!
interface Serial0/0/1:0

no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1
!

[Router 2]

!
interface Multilink1
ip address 192.168.100.2 255.255.255.252
ppp multilink
ppp multilink group 1
!
interface Serial0/0/0:0

no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1
!
interface Serial0/0/1:0

no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1
!

You may activate other features like tcp-header compression on the link. Note that ip processing features on the link will be processed based on multilink interface.