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RWIN? Any ideas?


RL317
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I went to the TCP Analyzer website because I wanted to see what using auto MTU would do on my Netduma and PS4; I normally use 1492 set manually as I'm on a PPPoE line, and wanted to make sure using auto on the PS4 didn't set it to 1500.

 

Anyway further down the page, something caught my eye. It said my RWIN was not optimised at 68000 or so, because it was not a multiple of my MSS (MTU -40 right?). It then suggests using one of the following values:

 

63888 (up to 2 Mbit lines, depending on latency. MSS * 44)

127776 (1-5 Mbit lines, depending on latency. MSS * 44 * 2)

255552 (2-14 Mbit lines, depending on latency. MSS * 44 * 2^2)

511104 (8-30 Mbit lines, depending on latency. MSS * 44 * 2^3)

1022208 (25-60 Mbit lines depending on latency. MSS * 44 * 2^4)

 

If I load up this page on my phone using Google Chrome, it says this:

 

"Default TCP Receive Window (RWIN) = 87616

RWIN Scaling (RFC1323) = 6 bits (scale factor: 2^6=64)

Unscaled TCP Receive Window = 1369

 

You seem to be using Google Chrome. Note that Chrome can modify the TCP Window for sockets it creates under some OSes, and therefore servers may not get your correct RWIN value. You may want to test with a different browser. FAQ

For optimum performance, consider changing RWIN to a multiple of MSS.

Other RWIN values that might work well with your current MTU/MSS:

 

63888 (up to 2 Mbit lines, depending on latency. MSS * 44)

127776 (1-5 Mbit lines, depending on latency. MSS * 44 * 2)

255552 (2-14 Mbit lines, depending on latency. MSS * 44 * 2^2)

511104 (8-30 Mbit lines, depending on latency. MSS * 44 * 2^3)

1022208 (25-60 Mbit lines depending on latency. MSS * 44 * 2^4) "

 

Question: is RWIN in any way relevant to gaming? Because it's apparently supposed to be a multiple of MSS I assumed it might play into MTU somehow, which obviously needs to be set to your line type's optimal value or you're going to have issues. Does RWIN have the same effect, or is it only related to webpages and browsing? If anyone could clear that up, that'd be great. It seems I can only change the RWIN using commands on a computer so maybe it is only specific to browsers.

 

Edit: I should add I'm not gaming on PC ;)

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Sometimes you have to think, I have far to much time on my hands, .lol.

Seriously, from a gaming point of view I think you are thinking far to much,.

Remember it takes around 300 to 400 ms to blink your eyes.

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Sometimes you have to think, I have far to much time on my hands, .lol.

Seriously, from a gaming point of view I think you are thinking far to much,.

Remember it takes around 300 to 400 ms to blink your eyes.

Haha I know, I was just wondering if it had an impact because I was unfamiliar with the term

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Haha I know, I was just wondering if it had an impact because I was unfamiliar with the term

 

You and me both!

I just saw a lot of numbers and acronyms, that was me out straight away  :huh:

 

I left the link to your post in the 'general' section too so more people will see it.

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