What is an MTU and why is it important?

MTU and fragmentation?

• My idea is to increase my computers throughput to my router. My router will then fragment the packets to a smaller size for more response for gaming. Will this work? What I've done is found the max MTU size without fragmentation. Tripled the size of the packet by that number for more throughput. Then set the MTU size for my router to fragment. Which could be equal to the MTU that's at the limit for my ISP or smaller for more responsiveness I assume. Is this a good idea for creating more responsiveness? I assume yes because I experienced more responsiveness for my game. MW3 of an average of 4 to 6 kills a match to 31. I notice a heck of a lot less lag. Then comes the question of the ISP's priority of the packets. Which i was wondering of a good website on information on how the ISP usually sets up QoS for packets. Thanks for the time and please no BS answers.

• Answer:

  I wouldn't do that. Even at 100mbps a maximum length ethernet frame will take a matter of 150 microseconds to transmit. Most home routers are comparatively underpowered and do not offer anything like wirespeed performance - typically they willl take somewhere between 200 and 500 microseconds simply to make a forwarding decision. This is something that has to be paid on a per packet basis - it doesn't really matter how big the packet is. Decreasing the MTU therefore means that you are increasing the number of packets and the amount of time spent performing this processing. You're unlikely to notice much difference when gaming since the packets will not be full length as a rule anyway, but you will notice the effect when downloading stuff. Worse still, if the router has to fragment incoming packets as a result of the reduced MTU that is an additional layer of processing and will take even longer. As for what strategies the ISP will adopt when managing their network that varies between providers. Most will prioritise web traffic ahead of other traffic types and many will throttle bandwidth-intensive uses such as file sharing. Ultimately, though you can't make definitive statements about ISPs generally. One thing we can be clear on is that they will have set their own policies according to what they think best: nothing you can alter on YOUR router will affect the traffic in the slightest once it hits THEIR network.