Also, if we're going to go for bigger MTUs, going from 1500 to 9000 is basically worthless, if we really want to do something, we should go for 64k or even bigger.
I agree but we need to work with what we have. Practically everything currently appearing at a peering point will support 9000. Getting equipment that would support 64000 would be more difficult.
About 1500 MTU degrading performance, that's a TCP implementation issue, not really a network issue.
True, but TCP is what we are stuck with for right now. Different protocols could be developed to handle the small packets better.
Interrupt performance in end systems for high-speed transfers isn't really a general problem, and not until you reach speeds of several gigabit/s. Routers handle PPS just fine, this was "solved" long ago after we stopped using regular CPUs in them.
We are starting to move to 10Gig + peering connections. I have two 10G peering ports currently on order. "several gigabits/sec" is here today.
Increasing MTU on the Internet is not something driven by the end- users, so it's not going to happen in the near future.
It depends on what those end users are doing. If they are loading a web page, you are probably correct. If they are an enterprise user transferring log files from Hong Kong to New York, it makes a huge difference, particularly the moment a packet gets lost somewhere. At some point it becomes faster to put data on disks and fly them across the ocean than to try to transmit it by TCP with 1500 byte MTU. Trying to explain to someone that they are not going to get any better performance on that daily data transfer from the far East by upgrading from 100 Mb to GigE is hard for them to understand as it is a bit counter-intuitive. They believe 1G is "faster" than 100Meg, when it isn't. If you tell them they could get a faster file transfer rate by using a an OC-3 with MTU 4000 than they would get by upgrading from 100Mb ethernet to GigE with MTU 1500, they just don't get it. In fact, telling them that they won't get one iota of improvement going from 100Mb to GigE doesn't make sense to them because they believe GigE is "faster". It isn't faster, it is fatter. And yes, TCP is the limiting factor but we are stuck with it for now. I can't change what protocol is being used but I can change the MTU of the existing protocol. I believe the demand for such high-bandwidth streams is going to greatly increase. This is particularly true as people move out of academic environments where they are used to working on Abilene (Inet2) and move into industry and the programs they built won't work because it takes two days to send one day's worth of data. There are end users and there are end users. It depends on the sort of end user you are talking about and what they are doing. If they are watching TV, they might want a higher MTU. If they are on Twitter, they don't care. Industry end users will have different requirements from residential end users.
They are just fine with 1500 MTU. Higher MTU is a nice to have, not something that is seriously hindering performance on the Internet as it is today or in the next few tens of years.
I disagree with that statement because I believe that the next few years will see an increased demand for high-bandwidth traffic that needs to be delivered quickly (HDTV from Tokyo to London, for example). One of the reasons people aren't interested is because they don't know. They are ignorant in most cases. They just know "bandwidth". They believe that if they get a fatter pipe, it will improve their viewing of that Australian porn. Then they pay for the upgrade and it doesn't change a thing. It doesn't change the data transfer rate at all. They go from a 10Meg to a 100Meg pipe and that file *still* transfers at 3Meg/sec. If they could increase the MTU to 9000, they might get 15Meg/sec. But you are correct, going to an even higher MTU is what is really needed but going for what is attainable is the first step. Everyone can physically do 9000 at the peering points (or at least as far as I am aware they can) and the only thing that is preventing that is just not wanting to because they don't fully appreciate the benefit and believe it might break something. Increasing MTU never breaks PMTUD. PMTUD is only needed because something in the path has a *smaller* MTU than the end points. The end points don't care of the path in between has a larger MTU.