The mpls fragment enable command enables packet fragmentation on a board that provides the MPLS transit node function. After this command is run in the slot view of a board that provides the MPLS transit node function, the board compares the packet length with the effective MTU before sending a packet that contains an inner IPv4 header and less than or equal to five layers of labels. If the packet length is greater than the effective MTU, the board fragments the packet.
The undo mpls fragment command disables packet fragmentation on a board that provides the MPLS transit node function.
By default, packet fragmentation is disabled on a board that provides the MPLS transit node function.
Usage Scenario
If PEs do not fragment packets or MTUs cannot be negotiated on a network with both Huawei devices and non-Huawei devices, to prevent packet loss, run the mpls fragment enable command to enable the fragmentation on a transit node (including a P).
Precautions
Packet fragmentation on the MPLS P node takes effect on MPLS packets that only have less than or equal to five labels and inner IPv4 labels. If the DF flag is set to 0 in the IPv4 header, fragmentation is performed. If the DF flag is set to 1, fragmentation can be performed only after the ipv4 force-fragment enable command is run.
In VS mode, the mpls fragment enable command can be run in the slot view only on the admin VS to be shared by all VSs and is unconfigurable on VSn.