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[kezzaman]

hello,

Can talktalk give some1s line a fixed mtu, for example 1364?

[GunJack]

not to my knowledge...... but it may depend on which DSLM/MSAN you're on. If you're on a TT one (ADSL2+) then their default MTU is/was 1432. If on an ex-tiscali one it will be 1458. If you must, try changing this in your router, but I doubt it'll make much difference. If on W7/vista, probably best setting the router for 1500 (see below).

Plus, vista and W7 auto-tune the pc's mtu to match what the network is supplying anyway. So as long as your router is at or above the network's mtu, and running vista or W7, there shouldn't in theory be a problem.

Actually, setting your mtu too low will deffo lead to packets being fragmented, and so introducing more scope for error during the fragmenting/reconstituting of the packets....better set too high than too low if on vista/W7....IMHO of course

If running XP, then try setting the router to 1432 or 1458 depending on which kit you're on, and using something like TCPOptimiser to set the MTU on the pc to match..

[kezzaman]

Its actually more about xbl i care about and not my laptop thats working fine. On sites ive read that the higher the mtu the better and on some sites i read its better to be lower and also divisible by 8. I dont know whats best for PC's but i know that 1364 is the optimum for gaming on xbl, microsoft told me in an email.

[kitz]

MTU will be affected by the minimum MTU at any point between your machine to the remote server.

>>> i know that 1364 is the optimum for gaming on xbl,

1364 is the MINIMUM and NOT necessarily the optimum. 
Setting it too low WILL result in fragmentation. 

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If you wish and just out of interest, you could use your laptop to see what the MAXIMUM MTU size your ISP uses - Working out your maximum MTU.

However I would NOT recommend setting the router to 1364 as this will likely cause fragmentation at some point and TBH I would think leaving the router MTU at 1500 would be best.
Theres a very good reason for that.  MTU is end to end point and therefore if you set it too low then the router itself will become the point of fragmentation.
Leaving it at 1500 will just allow packets to pass through unhindered by the router and let the xbl and the game sever negotiate their own MTU.

I dont know much about the XBL but afaik you cant tweak the MTU settings on the machine itself, the very last thing you want as a gamer, is for your router to become the point of fragmentation.  You just have to ensure that the router's MTU is equal to, or more than your maximum MTU size for your ISP's network.

>> on some sites i read its better to be lower and also divisible by 8.

Since you cant tweak the MTU on the xbox machine itself.. these are all rather moot points.
If you were talking about tweaking on the local machine itself then we can start talking optimum MTUs and why its good to be divisible by 8 etc.  Other than that all you can do is make sure that your router doesnt become the point of fragmentation.

[kezzaman]

Man i dunno...

Ive tried many different mtu values and what usually would happen is some would just be terribly laggy and 1500 was 1 of those tbh, but some would be good to start of with but then deteriorate with time, these values were 1432 and 1458, but the best was 1364. So 1432, 1458 and 1364 would all good to begin with then after a day or 2 they'd all become laggy, im guessing because of fragmentation, but in the end 1364 was deffinately the least laggyest, i contacted microsoft and they confirmed 1364 was the optimum value for gaming on their console.

But anyway i believe in all those circumstances my packets were fragmentating and i really cant think why, ive tried different routers and if its not the router and its not xbl what else can cause fragmentation, im thinking something at the exchange...

1 thing i remember seeing but i cant blummin find it now, its that my exchange (EMHORSL) was twinned with a neighbouring village, i think it was that my exchange is connected to theirs, dunno if the dslam on my 1 runs on a different mtu than their 1. Im just guessing at anything here, im determined to find a solution.

[burakkucat]

Have you tried asking for advice on the TalkTalk members forum? I would suspect that there are a number of people frequenting the gaming forum who would possibly have an idea, from practical experience. 

[kezzaman]

Ive tried everything, being looking for a solution for years, with 3 different ISPs. 

[burakkucat]

I really don't know what to suggest.

I have been with TalkTalk, on a LLU'd line, for four and a half years. I am not a gamer. I have the MTU set to 1432 in my router and likewise set in my desktop workstation. In my laptop, MTU is set to automatic, as it depends upon what I am doing & where.

 

[GunJack]

i contacted microsoft and they confirmed 1364 was the optimum value for gaming on their console.

I wonder if this is because xbl has been optimised  for gaming in probably their biggest market, ie. USA, and the broadband connections in use over there ??

[kitz]

One thing that must be asked first is that make sure that your router is ping able.  This fact is very important because if your router isn't pingable and you have ICMP turned off this will stop Path MTU  discovery working.... And in effect breaking mtu and even parts of the Internet.

Go to somewhere like grc.com and make sure that ICMP is on and your router is pingable.

See: -  Why is Path MTU Discovery not working?
http://www.kitz.co.uk/adsl/MTU.htm

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Next.. If I were you I would use your laptop to see what the max mtu is for your connection.    

The instructions on how to do this are here
Working out your maximum MTU.  
http://www.kitz.co.uk/adsl/MTU2.htm

Before you do this you must make sure that you router is set at 1500 to ensure that you are not getting any fragmentation at your router and to get a true figure.

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>>>>> contacted microsoft and they confirmed 1364 was the optimum value for gaming on their console

I stand by my original comments.  I would not recommend ever setting a uk router to 1364.   This value is too low for uk networks and at some point u will encounter mtu weirdness ... not necessarily on the Xbox..  but normal day to day traffic on any other machine.

M$ gaming servers for the Xbox live may well use 1364 ( I don't know if they do or don't). But either way .... If PMTUD is working as it should.... Then your Xbox will negotiate the packets for 1364 as long as your router is set at a higher figure.    During transit the packets will pass literally through 100's of other switches and routers therefore you just need to ensure that ur router isn't too low.  Ideally u want to match it with TTs network... So it's in tune with their routers and therefore minimising fragmentation at your router.  Matching it to the max (see my point 2) is going to make sure that u won't get fragmentation that's not going to happen on the TT network anyhow.


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I've just had a very quick google to try find the Xbox live mtu official figure and Microsoft seem to say min 1364 max 1500

.  I have however spotted some horrendous garbage and misinformation on the net about mtu for the Xbox... Particularly on you tube.... Including 2 videos that have literally taken stuff from my site without even understanding what they are doing.   I was in stitches at the vid which lifted info for setting mtu on a vista machine as a supposed cure.   I'm not quite sure how setting mtu on a vista pc is going to affect the mtu for the Xbox ....   And then he wondered why there was a pile of comments from pple saying it either broke their internet connection... Or it didn't work

[kezzaman]

Hello Kitz,

I really apretiate u taking the time to look into this for me, thx for that.

I trialed out having icmp over wan enabled on my dgteam netgear and sadly nothing improved 

Im thinking now that it cant be my network, theres nothing i haven't tried and im pretty sure most players on XBL dont have to go through all this trouble.

It has to be something at the exchange but what  Ive had 3 different isp's bt, virgin and now talktalk. Obviously with talktalk im on a different dslam so cant be that, Whats diifferent about my exchange than most others.... thats the million microsoft points question. 

[kezzaman]

Hello,
 
Ive been intouch with TT and turns out my DLM was already atually disabled, do you think i should trying having it enabled?

[roseway]

DLM is nothing to do with the subject. If your connection is stable, enabling DLM will make no difference, but if it's unstable, then DLM might increase your target noise margin (with a consequent drop in connection speed) to make the connection more stable.

[kezzaman]

Ok thx Roseway,

Another thing, on my router settings under, ATM VC settings i have Service category and in that i have UBR which is what its on, or
CBR, NRT-VBR, RT-VBR and UBR+.

Would changing to any of these help my predicament?