Thoughts on increasing MTUs on the internet

Thu Apr 12 18:08:05 UTC 2007

On (2007-04-12 19:51 +0200), Iljitsch van Beijnum wrote:
 
> 8 bytes preamble
> 14 bytes ethernet II header
> 20 bytes IP header
> 20 bytes TCP header
> 12 bytes timestamp option
> 4 bytes FCS/CRC
> 12 bytes equivalent inter frame gap
> 
> 90 bytes total overhead, 52 deducted from the ethernet payload, 38  
> added to it.
> 
> 90 / (1500 - 52 = 1448) * 100 = 6.21
> 
> 90 / (9000 - 52 = 8948) * 100 = 1
> 
> Also note that the real overhead is much bigger because for every two  
> full size TCP packets an ACK is sent so that adds 90 bytes per 2 data  
> packets, or increases the overhead to 9% / 1.5%.

Aren't you double penalizing? Should it be:
[ytti at nekrotuska ~]% echo "90 / (1500+38) * 100"|bc -l     
5.85175552665799739900

Or other way to say it:
[ytti at nekrotuska ~]% echo "100-(1448/(1+7+6+6+2+1500+4+12)*100)"|bc -l
5.85175552665799740000


-- 
  ++ytti