How is the MTU of an AR interface changed

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The network layer limits the size of data frames. When a network layer device receives an IP packet, it determines the outbound interface and obtains the MTU configured on the interface. The IP layer then compares the MTU with the packet length. If the packet length is longer than the MTU, the device fragments the IP packet. Each fragment has the smaller or equal size as the MTU.
If forcible unfragmentation is configured, some packets may be discarded when transmitted at the IP layer. Therefore, large packets must be forcibly fragmented to prevent packet loss on the network. The mtu command is used to set the size of a fragment.
The MTU value can be configured for Layer 3 interfaces only. The commands are as follows:
[Huawei] interface gigabitethernet1/0/0
[Huawei-GigabitEthernet1/0/0] mtu 1200
[Huawei-GigabitEthernet1/0/0] restart

Other related questions:
How to configure the MTU for an interface on a CE series switch
The procedure for configuring the MTU for an interface on a CE series switch is described on the right.

Can we change MTU for vlan interface ?
yes, we can. For example: [HUAWEI] interface Vlanif 100 [HUAWEI-Vlanif100] mtu 1492

How can I set the MTU value of the conference endpoint?
The default MTU value of the conference endpoint is 1500. You can choose System Settings > Network > Common Settings on the web page of the TE to change the value.

Is the MTU of an interface configurable
The maximum transmission unit (MTU) of Layer 3 interfaces is configurable. The MTU of Layer 2 interfaces is not configurable.

How is the TCP MSS of an AR interface changed
The TCP MSS specifies the maximum length of TCP packets that can be received by a device. When setting up a TCP connection, the local and peer devices negotiate an MSS value to determine the maximum data length of TCP packets. If the length of TCP packets sent from the peer device exceeds the MSS value, the packets are fragmented. To prevent TCP packets from being fragmented, you must configure a proper MSS based on the maximum transmission unit (MTU). The MTU determines whether IP packets will be fragmented. If the size of an IP packet exceeds the MTU, the IP packet will be fragmented. To ensure that a complete packet is transmitted properly, the MSS value plus all the header lengths (TCP header and IP header) cannot exceed the MTU. For example, if the default MTU value of an Ethernet interface is 1500 bytes, to ensure that packets are not fragmented, the maximum MSS value can be 1460 bytes. 1460 = 1500 �?20 (TCP header) �?20 (IP header) You are advised to set the MSS value to 1200 bytes. An improper TCP MSS value may lead to slow network access. To set the TCP MSS, run the following commands: [Huawei] interface gigabitethernet1/0/0 [Huawei-GigabitEthernet1/0/0] tcp adjust-mss 1200

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