Statement introduced before Junos OS Release 7.4.
Clear the don’t-fragment (DF) bit on all IP version 4 (IPv4) packets entering a generic routing encapsulation (GRE) tunnel. If the encapsulated packet’s size exceeds the tunnel’s maximum transmission unit (MTU), the packet is fragmented before encapsulation. The statement is supported only on MX Series routers and all M Series routers except the M320 router.
When you configure the clear-dont-fragment-bit statement on an interface with the MPLS protocol family enabled, you must specify an MTU value. This MTU value must not be greater than maximum supported value, which is 9192.
Required Privilege Level
interface—To view this statement in the configuration.
interface-control—To add this statement to the configuration.