Re: [colorforth] bulk transfer protocol

["Samuel A. Falvo II" <kc5tja@xxxxxxxx>]

On Wednesday 05 May 2004 11:52 am, howerd.oakford@xxxxxxxxxxxx wrote:
> TCP is general purpose, but in practice uses packets consisting of 512
> bytes of payload plus 20 bytes of header info.
> The 512 bytes matches one disk sector on many ( older ) OS's.

I'm unfamiliar with this "common" usage.  When I was working for the ISPs 
I managed, our MTUs were regularly set to 1500 octets, which seemed to 
work well, EXCEPT for our dial-up modem users, which used 576.

> The Internet guarantees that packets less than 576 bytes will not be
> fragmented by the IP layer, so these packets will arrive complete (
> not as several IP packets ).

This is perhaps true for wired networks.  For wireless, especially those 
relying on X.25 or (especially) AX.25 as layer-2 protocols, it's common 
to fragment packets at 256 octets.

Not trying to make trouble, but the point is, "Never assume anything."

--
Samuel A. Falvo II


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