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Hierarchy Level


For a generic routing encapsulation (GRE) tunnel, enable fragmentation of GRE-encapsulated packets whose size exceeds the maximum transmission unit (MTU) value of a link that the packet passes through. The don’t-fragment (DF) bit is not set in the outer IP header of GRE-encapsulated packets.

To enable the reassembly of fragmented GRE-encapsulated packets on GRE tunnel interfaces at the endpoint of the GRE tunnel, include the reassemble-packets statement for the interface.


The reassemble-packets statement is not supported on MPC10E line card in Junos OS Release 19.3.


If you do not include the allow-fragmentation statement, fragmentation of GRE-encapsulated packets is disabled.

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 9.2.

Statement introduced in Junos OS Release 19.3 for MPC10E line card.