MTU requirement for Streaming

Description

MTU stands for "Maximum Transmission Unit." It refers to the maximum size of data packets that can be transmitted over a network in a single transmission. A data packet is a fundamental unit of data used for transmitting information across a network. It is a formatted block of data that contains both the actual data to be transmitted (payload) and additional information used for routing and delivery (headers). So in other words, MTU is the largest data packet that can be sent from one device to another without being fragmented into smaller pieces.

If the data packets size exceeds the MTU, the data must be fragmented into smaller packets for transmission. Upon reaching the destination, the packets are reassembled to reconstruct the original data. While fragmentation allows data to be transmitted across networks with varying MTUs, it can also introduce some overhead and potential performance issues. For example:

1. Increased Overhead: The header information is duplicated in each fragment, which increases the overall overhead of the transmission.

2. Fragment Loss: If one or more fragments are lost during transmission, the receiving device cannot properly reassemble the original packet, leading to retransmission requests and potential delays.

3. Delay and Latency: The reassembly process can introduce some latency and processing overhead on the receiving device.

Let's consider an example where data needs to be sent from Computer A to Server A, but it must pass through Router B and Router C. Computer A, Server A, and Router B all have an MTU of 1500 bytes. However, Router C has a smaller MTU of 1400 bytes. In this scenario, when the data packet reaches Router B and needs to be forwarded to Router C, it will be fragmented into two parts: one with 100 bytes and the other with 1400 bytes.

To maintain efficiency and minimize delays during packet transmission, it's advisable to avoid fragmentation whenever possible due to increased overhead and potential retransmission requests if fragments get lost during transit. To ensure smooth data transfer, it's essential to configure the MTU appropriately on all network devices along the path, so data packets can be transmitted without the need for fragmentation.

Solution

Dolby.io streaming services can accommodate packets of any size, but larger packets are preferred for optimal performance. If a packet is too small, it may become fragmented during transmission, but in general, properly sized packets should arrive without issues. However, if any fragment of a packet is lost, the entire packet is considered lost.

To ensure smooth streaming, we recommend using an MTU of 1500, but it should not be set below 500 due to the risk of fragmentation. Most networks support an MTU above 1000, making it unlikely that users will encounter compatibility issues. You can select the largest MTU value supported by your network or simply rely on the network's default settings.

Setting the MTU depends on the operating system of your device. You can configure the network settings and specify the desired MTU value using the command prompt (on Windows) or terminal (on macOS and Linux).

Conclusion

In conclusion, the Maximum Transmission Unit (MTU) plays a crucial role in data packet transmission over networks. To maintain efficient data transfer, it is recommended to configure the MTU appropriately on all network devices to avoid fragmentation.

Affected Product

• Dolby.io Streaming

References

• What is MTU