Westermo RedFox Series - Manual (Page 428)

Westermo OS Management Guide
Version 4.17.0-0
Context Interface Configuration context
Usage Configure a non-default maximum transmission unit (MTU) size (in bytes)
for this interface. The MTU size is the packet size a network interface will
pass to the link layer for transmission, i.e., the maximum payload of the link
layer protocol.
The default is to let the MTU depend on the type of link layer (auto mode).
For interfaces associated with Ethernet and DSL links this implies a default
MTU of 1500 bytes.
For PPP interfaces (PPPoE), the MTU is set to 8 bytes less than the MTU of
the associated VLAN interface, which typically implies a PPP interface MTU
of 1492 bytes (1500 − 8). This value is set at the time of PPP interface
creation; if the VLAN interface MTU is changed afterwards, the PPP interface
MTU is not updated automatically. Note: The operational MTU can change
based on the PPP connection negotiation, see
section 33.3.19 .
The MTU of GRE interfaces defaults to 1476 bytes.
Use ”mtu <68-1500>” to set a non-default MTU size. Use ”no mtu” to spec-
ify that the interface should let its MTU be the default MTU of the associated
link type.
Use ”show mtu” to how the interface maximum transfer unit (MTU) size
setting.
Default values
❼ VLAN interfaces: Auto (”no mtu”) For Ethernet and DSL links, this im-
plies MTU 1500 bytes.
❼ GRE interfaces: 1476 bytes (”mtu 1476”)
❼ PPP interfaces (PPPoE): Typically 1492 bytes (”mtu 1492”, i.e., 8 bytes
less than the associated VLAN interface)
19.6.9 Interface TCP MSS Size
Syntax [no] tcp-mss <40-1460|auto>
Context Interface Configuration context
Usage Enable/disable TCP-MSS clamping on this interface.
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