Joshua D Boyd
jdboyd at cs.millersville.edu
Sat Sep 28 19:21:34 CDT 2002
On Sat, Sep 28, 2002 at 08:15:15PM -0400, Dave McGuire wrote:
> On Saturday, September 28, 2002, at 05:11 PM, dave at cca.org wrote:
> >> Yeah, that'd be great if ATM didn't SUCK.
> >Why does ATM suck? Tiny packet size?
> 53-byte cells. Router CPUs spending all their time reassembling
> packets. 53 bytes is even significantly smaller than the smallest
> possible TCP packet size in a telnet session (71 if memory serves? too
> tired to add it up right now).
53bytes is prime, which is pretty stupid. Ideally it would a multiple
of 2, 4 or 8 bytes. But, also stupid is that the payload on that 53byte
packet is 48 bytes. Why 48 bytes? Because certain countries couldn't
decide between 64bytes and 32 byte payloads. Reportedly, telecom people
wanted 32bytes and datacom people wanted 64bytes. So the committee
compromised at 48 bytes, which in either case (datacom or telecom) is
worse than the other options.
In my opinion, ATM was networking by suits. Still, it would be kinda
cool to have, but only if it was the fast stuff not those 25mbit cards
that are so cheap currently.
Joshua D. Boyd
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