Using a firewall filter to prevent or allow datagram fragmentation

You can define a firewall filter term to prevent or allow datagram fragmentation by setting or clearing the Don't Fragment flag in the IPv4 header of packets that are matched by the filter. Specify the desired action at the [edit firewall family inet filter filter-name term term-name then action] hierarchy level. 

• To prevent fragmentation of the IP datagram, include the dont-fragment set action in a term to set the dont-fragment bit to one. 
• To allow fragmentation of the IP datagram, include the dont-fragment clear action in a term to clear the dont-fragment bit to zero.