MTU (Maximum Transmission Unit) refers to the maximum packet size that a network can transmit, in bytes. MTU determines the maximum number of bytes that the sender can send in one packet. If the MTU is too large and exceeds the maximum value supported by the receiver or a device on the transmission path, packets may be fragmented or even dropped, increasing the network transmission burden. If the MTU is too small, the actual amount of transmitted data is too small, affecting transmission efficiency.
ACOS supports configuring MTU for virtual networks, including system networks and VM networks, and physical network ports.
When configuring the MTU of a virtual network, if the MTU of any corresponding physical network port is smaller than the MTU of the virtual network, you must select Increase the MTU of the associated physical network port to ... at the same time during configuration. The system automatically adjusts the MTU of the physical network ports to be the same as the MTU of the virtual network. If the MTU of any corresponding physical network port is larger than the MTU of the virtual network, the system does not decrease the MTU of the associated physical network ports at the same time.
After the MTU of a VM network is modified, if a VLAN virtual NIC uses the VM network, the virtual NIC automatically applies the same MTU. If the virtual NIC is an SR-IOV passthrough NIC, it does not automatically apply the MTU of the VM network. If the virtual NIC is an E1000 virtual NIC, only an MTU of 1500 is supported.
When modifying the MTU, ensure that the MTU of all nodes on the link is consistent. Therefore, the MTU of the physical switch connected to the physical network port must also be adjusted accordingly.
