MTU - Please Reply Ian

[Wake]

Now MTU is something I recently learned, and a lot of people don't really understand it and many router,consoles,computers, etc... don't go in huge detail with it as well they just let it sit as automatic and that's that. But after lots of tweaking and trying my best to make it matter I've come to talk about my results and see if maybe anyone or Ian can discuss this with me.

 

So originally my MTU was set to 1500, and after review I saw that when I had my R1 in it stayed at 1500. And trust me I've tried every trick in the book but I couldn't really find any success in making my connection (Lag) better than it was. Don't get me wrong, before all this the R1 had its ups and downs and I still love the thing. It's just I can't sit around and play xbox and sometimes feel serious lag and I can't do anything about it. So I started doing major research on MTU and I did some ping test with other MTU values and experimented with this a few times. Currently I'm at 1480, which I got to because when doing tests on my X1 I saw that the Xbox gives you that as default. Which was weird because I had 1500 set on everything else. After completely switching all MTU on PC,Router,Xbox. I saw great results in gameplay. I felt like I was playing amazingly, and maybe it was a good lobby or so, but after days of good results I found that this might have actually worked.

 

So my question is does MTU "matter" and is this just a thing I did and I'm lucky it helped but it's not like its a major breakthrough.

 

So thanks for reading guys.

 

  -Blake

[faulko]

Others in "the know" will answer better then me but that im aware MTU is relation to packet size or similar.

When you have a higher MTU then your provider, this opens the door for packet fragmentation, fragmentation = more packet needed to be sent/recieved.

Will you see a different if corrected to no fragmentation required, no i doubt it, unless you have an incredably unstable connection then you a purely contributing to an already present issue.

Ive seen various stuff about the net and some swear by using a mtu in the 1300's, i tried it and made the game worse.

We see alot of this type of stuff around the net and i can only assume that folks are trying to create a lan feel game online, it doesnt work never has and never will, there are just to many differences in ping and traffic flow across the world.

Sometimes the basics are enough and thats all you will get. Trying harder and harder to get that ultimate "lan feeling" edge will only result in 1 thing, more frustration. Sometimes we just have to deal with it and move on.

Try this http://www.letmecheck.it/mtu-test.php and adjust your devices.
 

These are my results and i didnt see any difference, well maybe alittle but im better that was a placebo.

 

 

Sending 32 bytes to 124.168.136.6 <- not fragmented

Sending 750 bytes to 124.168.136.6 <- not fragmented

Sending 1125 bytes to 124.168.136.6 <- not fragmented

Sending 1313 bytes to 124.168.136.6 <- not fragmented

Sending 1407 bytes to 124.168.136.6 <- not fragmented

Sending 1454 bytes to 124.168.136.6 <- FRAGMENTED!

Sending 1430 bytes to 124.168.136.6 <- not fragmented

Sending 1442 bytes to 124.168.136.6 <- FRAGMENTED!

Sending 1436 bytes to 124.168.136.6 <- not fragmented

Sending 1439 bytes to 124.168.136.6 <- FRAGMENTED!

Sending 1437 bytes to 124.168.136.6 <- FRAGMENTED!

Sending 1436 bytes to 124.168.136.6 <- not fragmented

 

From the tests we did, we can assume that 1436 bytes is the largest unfragmented packet size. The MTU size would be 1464, made up from 1436 payload and 28 ICMP/IP Headers and payload information.

 

The current maximum payload size is not divisible by 8. The actual size of the payload (data) will be limited to: 1432

The maximum MTU size for 124.168.136.6 is: 1464

[Od1n]

just did a test, my Xbox MTU is 1480 so smaller than my maximum MTU

will it be benefitical to increase my MTU to 1492?

 

testresult:

"The maximum MTU size for XXXXXXXXX is: 1492"

[faulko]

I wouldn't think anyone would notice a huge improvement Od1n, but i don't know the full ins and outs of it all and i could be totally wrong.

I can say thou is that ive tried all sorts of ideas over the years and not 1 has made a noticeable improvement so i just gave up and did the basics and just let it be what it is.

One thing the duma has proven to me thou is the closer the ping of all the lobby members the better then game play. Start adding 50-70ms difference in the 1 lobby and it all goes pear shaped.

Unfortunately there is only 1 server in AUS/NZ that im aware of and every one plays of that, 15ms-100ms, since i cant kick them out we in AUS/NZ just have to deal with it and get on with it.

try it thou, it cant hurt. 

[Netduma Fraser]

It is definitely good to have your MTU's set to the same so that you avoid fragmentation. If you tested it and found the MTU without fragmenting to be the same as Xbox it would stand to reason that it would be optimal to have them set at that value. So it would only help you by doing it, but as far as being a massive improvement I wouldn't have thought so. Could be wrong but thats my thoughts on it, glad to see you're having a good experience

[Od1n]

so using your max MTU (unfragmented) is the best?

 

i mean i can see that you preferably would want to use an unfragmented MTU, but 32 bytes or 750 bytes are also unfragmented, so the question is where is the optimum

[Netduma Fraser]

so using your max MTU (unfragmented) is the best?

 

i mean i can see that you preferably would want to use an unfragmented MTU, but 32 bytes or 750 bytes are also unfragmented, so the question is where is the optimum

 

The optimum is the closest you can get to under where you get fragmentation

[major masingil]

So if the console's MTU is 1480 we should set our router's MTU to 1480?  Or do we just keep it as automatic?

[fuzzy clam]

I have lowered my MTU to 1482 as that's what someone had suggested on PS3 that was having good results.And to be honest it didn't make much difference IMO as long as your MTU matches on your routers and your gaming console,you should be good to go.I know some people like to play around with it,but for me leaving it on automatic (1500) seems to be fine.

[Od1n]

The optimum is the closest you can get to under where you get fragmentation

 

thanks a lot Fraser

 

when i set my MTU to 1492 in the R1 settings will it automatically apply to all devices?

[Netduma Crossy]

when i set my MTU to 1492 in the R1 settings will it automatically apply to all devices?

 

Yes

[Od1n]

awesome, thanks Fraser and Crossy

and Wake for bringing this up

[Od1n]

just to double check if i did something wrong

 

when i go into R1 settings - WAN and set my MTU to 1492 and click apply, my Xbox One MTU value still is on 1480 regardless of restarts or whatsoever

is there anything else i need to do in order to change the MTU correctly?

[YEESH_DALE]

How is it that i have no WAN setting on my DUMA? Trying to set a custom MTU is proving impossible.. 

[Netduma Crossy]

How is it that i have no WAN setting on my DUMA? Trying to set a custom MTU is proving impossible.. 

 

Can you make a new thread please DALE and explain what the issue is cause I'm not sure i understand the problem

 

If it is that you can't find the MTU setting, then it is in Settings >> LAN.

[YEESH_DALE]

Done: http://forum.netduma.com/topic/7271-no-mtu-setting-under-settings-not-even-lan-option/

[Netduma Fraser]

just to double check if i did something wrong

 

when i go into R1 settings - WAN and set my MTU to 1492 and click apply, my Xbox One MTU value still is on 1480 regardless of restarts or whatsoever

is there anything else i need to do in order to change the MTU correctly?

 

1480 is default for Xbox so thats what it will take my the looks of it, other devices should use 1492

[Netduma Iain]

Sorry only just saw this thread. In most instances I would think that it makes no difference. MTU is the largest accepted packet size along the path you take on the Internet. If you line up all the networks you go through the one with the smallest MTU is your overall MTU for that path.

 

If you send a packet bigger than the MTU it gets fragmented. This can add latency because the packets have to be reassembled at the other end. This requires waiting for the slowest one. Also it's adds processing so it will reduce throughput as well (add a bit of scheduling latency ).

 

You don't want to make it too small, because the application(game) in this case could send datagrams that are larger and they will have to be fragmented. 

 

I haven't looked at xbox game traffic in a while, but from what I recall about games (well FPS) is they rarely use 1500 byte packets. So setting it to 1480 won't hurt the game, but it could hurt your system downloads.

 

tl;dr  Please don't mess with this setting its unlikely to make a difference and will cause far more harm than it will fix if you don't know what it means. 

[faulko]

just to double check if i did something wrong

 

when i go into R1 settings - WAN and set my MTU to 1492 and click apply, my Xbox One MTU value still is on 1480 regardless of restarts or whatsoever

is there anything else i need to do in order to change the MTU correctly?

i would set your devices to auto or make them the same number, the R1 wont change your xbox's mtu for you,

 

Make your router and modem (both if you have them)  to 1492 leave the rest of devices at auto or 1492, even go 1492 less 28 = 1464 if you really want just to be sure but im positive the 1492 will include the 28 header size.

 

Also and correct me if im wrong but setting your own mtu etc only effects your uploads, d/load packet would be sized by your ISP yes/no?

Having a 1500mtu and your isp sending you 1492 packets wouldnt hurt downloads would it?

 

Of course im no network guy only what i remember reading many moons ago.

[Netduma Iain]

Honestly all of this is theoretical because I've never really done anything practical with MTU, never had to. But from memory these are the scenarios:

 

1) If your PC is aware of the MTU and it is the smallest on the path then the TCP download will be smart enough to detect it as maximum segment size is an TCP establishment option(that is universal as its in the first RFC). So both ends are aware of the MTU (or correctly segment) size. But game traffic is UDP so this won't matter

2) If they do any form of MTU discovery, but I believe its almost useless on the Internet as many routers don't send correct error ICMP messages back. Iirc there is an alternative to traditional MTU discovery but I can't remember the nuance of it.

 

But anyway nearly all of this is irrelevant for this topic as game datagrams are typically way below Ethernet MTU limits. 

[R3M!X]

For those who play Destiny in here. Don't mess with your MTU. There is an exploit doing this that will pretty much make you invincible in PVP thus resulting to a BAN! According to bungie this is Network Manipulation for them so they will take action against you and temporary band or in worst case permanently BAN you.