Whats the true mtu here?
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Whats the true mtu here?
25-04-2021 10:04 AM - edited 25-04-2021 10:05 AM
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All I want to know is why my line or router links at 1488 is the line mtu 1488 or is mtu created in the home through the router I.e my xr500 setting it to 1492 should work optimally when intact it doesn't?.
Is there anyone that fully understands the line management and what the mtu max really is and why the plusnet router is set to 1488 there has to be a reason for shipping them and giving them to people to use with that mtu value.
Any help much appreciated
Thank you
Re: Whats the true mtu here?
25-04-2021 11:10 AM - edited 25-04-2021 11:18 AM
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I've been down this path. I presume you've done something similar but using your gaming portal instead.
FWIW Mine is 1488 (I'm not on a PN router or service) and seems ok
Re: Whats the true mtu here?
25-04-2021 11:34 AM
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Re: Whats the true mtu here?
25-04-2021 11:56 AM
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There's a lot of information about MTU and MSS (maximum Segment Size) available on the web - some of it is almost intelligible to a layperson. Here's a simple and incomplete overview...
Basically, MTU is the maximum packet size that can be sent over TCP. Each packet is made up of a header section and a data section. The MSS is basically the maximum size of the data section - and that is really just the MTU minus the header size.
Each protocol has a different header size, and individual applications may also add header information.
If a packet it larger than the MTU it will be split by the sender and sent as multiple packets - this is known as fragmentation. In the vast majority cases that works just fine. The cases where it doesn't may be due to the extra delay introduced, or by an application (e.g. games) not accepting split packets (often seen as dropped packets or broken connections).
Things such as VPNs or L2TP add to the packet header size - these are not always apparent to an end user as some ISPs may route traffic using L2TP, and the only visible impact is a lower MSS. A lot of the MTU discovery tools really report MSS - which is why you add some value (28 for icmp) to the result to arrive at an MTU to use.
The MTU applies to the whole path to each destination, so you can find that testing MTU for different destinations will report different values.
In general you may find a MTU that is lower than the detected maximum is more robust, and is unlikely to degrade throughput by a noticeable amount.
Re: Whats the true mtu here?
25-04-2021 1:59 PM
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I just wondered if there was a yes or no answer to plusnets infrastructure running at 1488 or the pppoe max of 1492.
Thank you
Re: Whats the true mtu here?
25-04-2021 2:34 PM
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The point is that the MTU is path dependent - only part of that path is within the Plusnet network. There isn't a defined value that is correct for all paths.
The MTU within Plusnet's network will depend on a number of factors, including whether you have a dynamic IP or a static IP (I understand the static IPs are routed over L2TP, so will have a lower MTU).
Re: Whats the true mtu here?
25-04-2021 4:07 PM
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My PS5 is wired and ports forwarded and haven’t had any issues with gaming on it.
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If it fixed it click 'This fixed my problem'
Re: Whats the true mtu here?
25-04-2021 4:57 PM - edited 25-04-2021 4:59 PM
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I've tried wired I've set up a geo filter to only connect me to the same server every time to eliminate randomness and different levels of ping to and from multiple random servers.
Nat type opened ports forwarded dmz tried it all. Mtu is definitely the difference in my tests so far.
As previously mentioned 1492 is max on my xr500 netgear router. On plusnet hub 1 it's 1488. After setting my netgear to 1488 or lower gaming is alot more consistent.
I guess as mtu isn't a massive factor when browsing or streaming I'll just find the best mtu that works for me over time.
I was just hoping there was a best/optimal for gaming so I didn't have to do this. Don't want it too low and only send x amount at a time but don't want it too high where everything is fragmented slowed down or lost
Re: Whats the true mtu here?
25-04-2021 5:59 PM
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If you have a gaming router then why not use that? Simply get a modem, a model 3B Huawei HG 612 works fine and can be picked up cheaply from an auction site, and scrap the Plusnet hub.
Router settings are here. https://www.plus.net/help/broadband/broadband-connection-settings/
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Re: Whats the true mtu here?
25-04-2021 6:13 PM
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And then figure out why the increased mtu to 1492 is affecting things
Thank you
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