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Re: Solving the need for ISA or USB slots and Serial Ports



Typo - I meant to say TCP.

Don Woodward
KD4APP
AMSAT 33535
kd4app@amsat.org
http://kd4app.webhop.org


----- Original Message ----- 
From: "Michael Kjorling" <michael@kjorling.com>
To: "AMSAT-BB" <amsat-bb@AMSAT.Org>
Sent: Wednesday, July 02, 2003 15:36
Subject: Re: [amsat-bb] Solving the need for ISA or USB slots and Serial
Ports


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On Jul 2 2003 14:59 -0400, Don Woodward wrote:

> UDP is not guaranteed for delivery whereas IP is - do you really want
your

I know this is a little bit off-topic but do feel that this statement needs
correction anyway. IP is not guaranteed for delivery.

The two most commonly used protocols on the Internet for ordinary
applications today are TCP and UDP, which use IP (IPv4 or IPv6) as their
"next lower layer", that is, lower meaning closer to the physical medium
(RF,
electrical cabling, light, whatever).

That is why IPv6 doesn't require TCP and UDP to be redesigned - only the IP
transportation protocol needed reworking. (Ah, the wonders of the OSI
model.)
Likewise, we could just as well run HTTP over a piece of string and two
empty
cans - HTTP only needs to be able to expect that a packet injected in one
end
gets delivered at the other end, and doesn't care about the technicalities
on
how that is accomplished. It would work exactly as well over IPX (which is
from the Novell world and has nothing to do with IP, by the way).

So, if you want to know that the package gets delivered without sending an
acknowledgement yourself, use TCP. If you don't really care (streaming
audio
is one application, DNS name resolution is another) then UDP is often
better
due to its lower latency. (One packet instead of three plus one plus
three.)


Michael Kjörling

- -- 
Michael Kjörling :: michael@kjorling.com :: SMØYBY JO89  ^..^
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