[Gllug] OT: MTU sizes, w/ Broadband

[John Hearns]

On Wed, 2003-05-14 at 15:04, Richard Jones wrote:

> 
> The 48 byte payload size *really* sucks for carrying the most common
> type of packet on the Internet - the TCP ACK. This packet is commonly
> 40 bytes in size, plus some overhead:
> 
> 40 bytes    IP packet
>  8 bytes    SNAP
>  8 bytes    AAL5
> 
> So it's 8 bytes too large to go in one cell. Instead it takes two
> cells. That's 106 bytes to transmit the most common 40 byte packet.

We know, we know (sigh)  'We' being proponents of ATM.
Just use the term 'cell tax' and I'll get all Glaswegian on yo' ass :-) 

The topic has come up before on GLLUG - 48 bytes was a compromise
between the US and Europe, to do with echo cancellation in phone calls.
And, yes, it is anathema to computer science types who, so far as I can
see, think only in powers of 2. Guess it makes it hard for them to buy
eggs, but there you are...





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