Maximum transmission units (MTUs) in devices

Maximum transmission units (MTU)

What is MTU size

MTU represents the maximum payload size of a network packet that can be transmitted across a network. It specifies the largest data size that can be encapsulated within a packet and sent from one device to another without being divided into smaller fragments. Maximum transmission unit size is measured in bytes, including the data payload and the packet headers.

Maximum transmission unit explained

When data is transmitted over a network, it is divided into packets for efficient delivery. These packets consist of a header section and a payload section. The header contains control information, such as source and destination addresses, while the payload contains the transmitted data. The MTU size determines the largest packet size that can be transmitted between two networked devices - across all intermediate network components.

US carriers

• AT&T: 1420 bytes

• Verizon: 1428 bytes

• T-Mobile: 1420 bytes

International

The recommended MTU size is 1400 bytes, which is internationally compatible with most mobile networks.

Other common MTU values

• LAN connection to LAN client: 1500 bytes

• WiMAX wireless WAN connection: 1400 bytes

• Cable/DOCSIS modem wired WAN connection: 1500 bytes

• DSL modem wired WAN connection: 1492 bytes

Resources

Refer to these resources for additional information.

• Tech tip - What MTU value should I use for my cellular connection?

• Cellular network — Importance of MTU on UPF performance & UE connectivity