How to change the Camera's MTU Size

Introduction

In computer networking, the maximum transmission unit (MTU) of a communications protocol of a layer is the size (in bytes) of the largest protocol data unit that the layer can pass onwards. MTU parameters usually appear in association with a communications interface (NIC, serial port, etc.). Standards (Ethernet, for example) can fix the size of an MTU; or systems (such as point-to-point serial links) may decide MTU at connect time.

A larger MTU brings greater efficiency because each network packet carries more user data while protocol overheads, such as headers or underlying per-packet delays, remain fixed; the resulting higher efficiency means an improvement in bulk protocol throughput.

A larger MTU also means processing of fewer packets for the same amount of data. In some systems, per-packet-processing can be a critical performance limitation.

However, this gain is not without a downside. Large packets occupy a slow link for more time than a smaller packet, causing greater delays to subsequent packets, and increasing lag and minimum latency. For example, a 1500-byte packet, the largest allowed by Ethernet at the network layer (and hence over most of the Internet), ties up a 14.4k modem for about one second.

Large packets are also problematic in the presence of communications errors. Corruption of a single bit in a packet requires that the entire packet be re transmitted. At a given bit error rate, larger packets are more likely to be corrupt. Their greater payload makes re transmissions of larger packets take longer. Despite the negative effects on re transmission duration, large packets can still have a net positive effect on end-to-end TCP performance.

Changing the Camera’s MTU Size

You can change the MTU-Size in the cameras configuration file.

  1. Open the cameras Admin Menu, and select “Edit configuration file”.

  2. Search for the SECTION ethernet

  3. Add the line ETH0_MTU=xxxx

Where xxxx is the desired MTU size, default is 1500.

Save this setting, and reboot the cam for changes to take effect.

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