mtu (MTI view)

Function

The mtu command sets the MTU for a multicast tunnel interface (MTI).

The undo mtu command restores the default MTU of an MTI.

By default, the MTU of an MTI is 1472 bytes.

Format

mtu mtu

undo mtu

Parameters

Parameter	Description	Value
mtu	Specifies the MTU value of an MTI.	The value is an integer that ranges from 46 to 1500, in bytes.

Views

MTI view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

If the length of a VPN multicast packet is equal or close to the MTU of the outbound interface of the public network instance, the length of the GRE-encapsulated public network multicast data packet is larger than the MTU of the outbound interface of the public network instance. In this case, the local PE must fragment the encapsulated packet and sends it through the outbound interface of the public network instance. Upon receiving the packet, the remote PE reassembles the packet.

You can set the MTU of the MTI to a smaller value so that VPN multicast packets can be fragmented before being encapsulated using the GRE. The remote PE does not need to reassemble the packets, improving efficiency.

Precautions

If the MTU is set too small and the size of packets is large, packets are broken into a great number of fragments, and may be discarded by QoS queues.

Example

# Set the MTU of MTunnel 10 to 1400.

<HUAWEI> system-view
[HUAWEI] interface mtunnel 10
[HUAWEI-MTunnel10] mtu 1400