Frame Relay can be used to group multiple physical interfaces in one logical interface, much like an EtherChannel interface available on the Ethernet Switches. It offers load-balancing and higher availability since the link will be up as long as one physical connection is up.
In order to do this, bothe the DTE and DCE device must be configured to support this configuration. As you will see, this is not an end-to-end configuration, but rather a local config, between the DTE and the local DCE. The DCE will switch the frames to the other DTEs just as with normal Frame Relay encapsulation
!On R2
R2(config)# interface serial1/2
R2(config-if)# ip address 123.0.0.2 255.255.255.0
R2(config-if)# encapsulation frame-relay
R2(config-if)# no shut
Verification
The logical MFR1 interface can be used just like a physical frame-relay interface. It can also be set up with subinterfaces. By default, dynamic Inverse ARP mappings will be assigned to the Multilink interface:
R1#sh frame-relay map
MFR1 (up): ip 123.0.0.2 dlci 102(0x66,0x1860), dynamic,
broadcast,, status defined, active
To verify the status of a Multilink bundle use:
R1#sh frame-relay multilink
Bundle: MFR1, State = up, class = A, fragmentation disabled
BID = MFR1
Bundle links:
Serial1/0, HW state = up, link state = Up, LID = Serial1/0
Serial1/1, HW state = up, link state = Up, LID = Serial1/1
