Multilink Frame Relay

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
MultiLink Frame Relay
First DTE
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!On R1:
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R1(config)# interface mfr1
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R1(config-if)# ip address 123.0.0.1 255.255.255.0
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R1(config-if)# exit
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R1(config)# interface serial1/0
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R1(config-if)# encapsulation frame-relay mfr 1
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R1(config-if)# no shut
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R1(config-if)# exit
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R1(config)# interface serial1/1
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R1(config-if)# encapsulation frame-relay mfr 1
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R1(config-if)# no shut
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Frame Relay Switch
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!On FRS:
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FRS(config)# frame-relay switching
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FRS(config)# interface mfr1
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FRS(config-if)# frame-relay intf-type dce
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FRS(config-if)# exit
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FRS(config)# interface serial1/0
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FRS(config-if)# encapsulation frame-relay mfr 1
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FRS(config-if)# no shut
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FRS(config-if)# exit
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FRS(config)# interface serial1/1
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FRS(config-if)# encapsulation frame-relay mfr 1
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FRS(config-if)# no shut
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FRS(config-if)# exit
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! FRS connects to R2 overs serial 1/2
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FRS(config)# interface serial1/2
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FRS(config-if)# encapsulation frame-relay
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FRS(config-if)# frame-relay intf-type dce
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FRS(config-if)# no shut
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FRS(config-if)# exit
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! Now let's glue them together:
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FRS(config)# connect R1_R2 mfr1 102 Serial1/2 201
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Second DTE
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!On R2
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R2(config)# interface serial1/2
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R2(config-if)# ip address 123.0.0.2 255.255.255.0
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R2(config-if)# encapsulation frame-relay
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R2(config-if)# no shut
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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:
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R1#sh frame-relay map
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MFR1 (up): ip 123.0.0.2 dlci 102(0x66,0x1860), dynamic,
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              broadcast,, status defined, active
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To verify the status of a Multilink bundle use:
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R1#sh frame-relay multilink 
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Bundle: MFR1, State = up, class = A, fragmentation disabled
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 BID = MFR1
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 Bundle links:
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  Serial1/0, HW state = up, link state = Up, LID = Serial1/0
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  Serial1/1, HW state = up, link state = Up, LID = Serial1/1
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Frame Relay Encapsulations – IETF vs Cisco

Frame Relay Switching

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