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mtu (Dynamic Profiles)


Hierarchy Level


Configure a per-subscriber maximum transmission unit (MTU) on a logical interface. A subscriber logical interface can specify MTU through its dynamic profile for the same underlying physical interfaces. The dynamic logical interface MTU must be no greater than the physical interface MTU minus the dynamic VLAN header size). You can configure either a static value or the predefined variable, $junos-interface-mtu. The value of the variable is returned by RADIUS during authentication in the Framed-MTU attribute (12). By default, the variable value is the MTU of the payload.

If you specify the predefined variable but RADIUS does not return a value in the Framed-MTU attribute,



MTU for the subscriber logical interface. You can specify a static value or the predefined variable, $junos-interface-mtu.

Required Privilege Level


Release Information

Statement introduced in Junos OS Release 18.1R1 on MX Series routers.