Unexpected speed increase (and a confession)

[UncleBob]

Hi all,

I've had a few router stability issues recently and, having undertaken some research on the interweb thingy, set about changing some of the settings on my router.

I initially had a rather poor 2MB download speed (was 1.7MB after the recent loss of service that affected many of us but picked up again after the recommended router reset).  After my various tweaks I am now getting speedtests indicating a speed of 3MB.  Now I know that is still pretty poor compared to many but its a big jump for me.

My confession is ... I don't really understand what I've done 

Anybody able to enlighten me if I provide some details?

OK, first of all I changed my MTU from the default 1500 to 1480.  I did this after doing some ping tests like this :  ping -f -l [packet size] [www.bbc.co.uk].  I kept going from 1472 downwards in steps of 10 until I was no longer getting 'fragmented packets' in the results.  I then added 28 to the figure. So, 1452 plus 28 gives 1480.  What the heck does that mean?

I then reduced my Beacon Interval from 100 to 75, and my Fragmentation Threshold and RTS threshold from the default 2346 for each to a figure of 2304.  Again, no clue what any of this means.

I feel a little embarrassed to have made these changes without really knowing what I was doing but they seemed to work for a great many people and they also seem to have had a positive outcome for me.  Please put me out of my misery so that at least if I tweak again I'll know why!

[sobranie]

Have a looky here Bob

http://www.kitz.co.uk/

[Niall]

Oddly, after all the problems in the Wrexham area, my line sped up. I know BT were working on things around here, but suddenly my line has it's profile set to the maximum it supports (14000). Downloads are generally around 1.1mb which is nice

[nowster]

Beacon interval is for wireless only. I've set mine to 250ms (4 per second). I'd suggest resetting Fragmentation Threshold and RTS Threshold back to their default values. They're also to do with your wireless LAN.

(Beacon interval is how often the base station sends out an "I'm here" packet. Fragmentation and RTS thresholds control what to do when the wireless signal is less than ideal.)

I would definitely suggest setting your MTU back to 1500. If it worked before, it should continue to work. There are tweaks to the MTU you can make that can yield a small increase in throughput if you can align the PPP packet size with an integer number of ATM frames, but they don't in any way affect your sync speed. (I assume that IDNet's backhaul can handle jumbo IP packets.)

[UncleBob]

Thanks for the replies.

Sobranie : Some useful stuff there for sure.  This is the sort of thing that I'd seen and used as the basis for the MTU change : http://www.kitz.co.uk/adsl/MTU2.htm

Niall : Yes, I suppose it could just be coincidence that my stats changed at the same time that I made the changes.  The cause could indeed be an external factor.  (Perhaps I'll change the settings back again to see what happens ...)

nowster : Sorry, I didn't specify in my OP - I am using a wireless router.  Can you elaborate on why you would return the settings back to what they were previously?  I'm not saying that isn't the right thing to do (I haven't a clue) I'm just curious as to the rationale.