What is the optimal MTU size for 1 Gbps?

Question

Computer networks

How to calculate the optimal MTU size for 1 Gbps? The gateway under ununtu 12 was installed and configured for a 100 Mbps network. They changed the provider and the channel was increased to 1 Gbps.

Answer 1

By increasing the MTU, we increase the packet size and the ratio of the header of the frames to the payload of this frame. Due to the fact that the amount of payload data in relation to the headers increases, the percentage of bandwidth utilization increases. But no one guarantees you that the frame will not be damaged along the way and it will not need to be sent again, so the more packets the more data will need to be sent (they say, due to a small error in a couple of bytes, you will have to send a new data block in a couple of kilobytes ).
Let's say the standard MTU size is suitable for everyone, jumbo frames were invented at a time when the number of packets was too large and the switches / routers did not have time to process it all and this did not allow the network bandwidth to be used to its full capacity, now there seems to be no such problem.
In short, I hope you get the idea. The more reliable the network, the higher you can set the MTU.

Answer 2

Here, Ethernet is in the tags, there is no more input data. Therefore, we will assume that we mean L2-MTU. You can talk about L3 separately, but the principles are the same.
If the network is office, everything is connected only via cable without RRL or satellite sections, you can set the maximum of those supported on the equipment (9000, on some 1700 on switches, depends on the equipment). True, you will not notice the difference compared to, for example, 1600.

Answer 3

If the question is theoretical (well, you never know, the teacher tests your knowledge), then there is such a Mathis formula that estimates the upper bound on TCP performance depending on MSS (i.e. MTU), RTT and packet loss probability. Read more here
If the question is applied, then I would ask you to clarify what kind of "speed 1 Gbit / s" is meant. What is the topology of the network, between which of its nodes do you need such a speed, through which devices the traffic you are interested in goes, how exactly this speed is set (i.e. either it's just a gigabit ethernet interface, or you need to steadily transfer user data at this speed).
In my opinion, when there is a separate compact SAN connecting servers and disk shelves, increasing the MTU makes sense. If, for example, it is supposed to generate traffic to the Internet, to end users, then I think you will not notice the effect (the MTU somewhere on user access will probably be less than yours)

Answer 4

Anyone at speeds up to 10 gigabits with sending large packets should not even think about changing the mtu and switching to jumbo frames

Answer 5

If you just have a gateway, without certain traffic features, then changing the MTU will give you a minimal performance boost. I wouldn't recommend touching it at all.