MTU - Benefits of large L2 MTU

When configuring a network, ensuring that the Layer 2 MTU is configured as large as possible is beneficial to improve the efficiency of traffic transmission. But this is only one of various parameters that must be configured. The MSS that is used in association with TCP is also an important part of ensuring efficiency across the network, and affects the level of efficiency that is actually achieved.

The reason for having a larger MTU (like 9000 bytes for example) is to increase the efficiency of data transfer. By increasing the amount of data that can be transferred in a single packet, you reduce the overhead of the IP and TCP headers on a per-byte basis. So by giving transmitting devices the option of using up to 9000 bytes MTU, any devices that take advantage of it will enjoy more efficient CPU usage and lower latency. However, all devices in the network path must support the larger MTU, or else fragmentation will occur, which can decrease performance.

Ultimately however, it is up to the end devices sending the traffic that decide the size of the MSS and this depends on the applications be using, as well as the capabilities of the devices themselves.

Links

https://networklessons.com/ip-routing/pppoe-mtu-troubleshooting-cisco-ios/