http://www.cavemen.co.za said:
Packetloss is generated by a MTU that is set too high.
I think that is a bit of a blanket statement to make. Packetloss is caused by many things, MTU certainly being last on the list of culprits, generally, and then only if the frame sent is larger than what the device can transmit.
http://www.cavemen.co.za said:
My results are as follows ... showing that even with 100% signal , the MTU is too high.
Packet needs to be fragmented but DF set.
You cannot transmit a ping with the exact same size of the MTU. The IP protocol has a header length of 20 bytes, and ICMP has an additional overhead of 8 bytes, so the maximum ping payload you can request on a 1352 mtu = 1352 - 28 = 1324 bytes. That's the maximum you can ping unfragmented, and it's also why you got the fragment errors when you pinged with "ping /f /l 1352".
It's got nothing to do with whether your connection can handle it or not. With a 1352 mtu you have to account for fixed overheads before trying a "don't frag" ping.
On ethernet the maximum unfragmentable ping = 1500 - 28 = 1472 bytes.
http://www.cavemen.co.za said:
So for me , my MTU needs to be 1208.
Wrong, you can set your MTU to 1208+28 = 1236 and things will still work
It is strange that 1208 gave you your first unfragmented reply - the iBurst MAC is perfectly capable of transmitting a 1352 frame. (this is partially due to the additional PPPoE overhead)
Your guide is more of a "misguide" than anything else. I don't know what your setup is, but for most people an MTU of 1352 is perfectly operable.
The bigger the MTU the better transfer rates you can achieve, so simply reducing the MTU to a small value can have a negative impact on performance. If you wanted to be absolutely safe you could set your MTU to the internet minimum of 576, and be sure that every router everywhere on the internet will be able to forward your traffic - except performance would suck.
I'd suggest studying some more, and reworking your blog post.
