# mtu

#### Syntax

mtu mtuSize

no mtu

#### Release Information

Command introduced before JunosE Release 7.1.0.

#### Description

Sets the maximum allowable size in bytes of the maximum transmission unit for interfaces on cOCx/STMx, CT3, COCX-F3, Ethernet, or POS modules. The no version restores the default value, which varies according to module type. This command is not available for the Ethernet interface on the SRP module.

#### Options

- mtuSize—Maximum allowable size of the MTU; default and range varies with interface type:
  - Interfaces on cOCx/STMx, CT3, and COCX-F3 modules—Number in the range 4–9996; default value is 1600
  - Interfaces on Ethernet modules—Number in the range 64–9188, except on the FE-2 and FE-8 I/O modules, where the range is 64–9042; you cannot configure MTU on Ethernet interfaces on the SRP module; default value is 1518
  - Interfaces on POS modules—Number in the range 1–9996; default value is 4470

#### Mode

Interface Configuration