Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!intercon!amanda@mermaid.intercon.com
From: amanda@mermaid.intercon.com (Amanda Walker)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: UDP - How unreliable?
Message-ID: <1629@intercon.com>
Date: 14 Dec 89 15:08:55 GMT
References: <1039@anasaz.UUCP>
Sender: news@intercon.com
Reply-To: amanda@mermaid.intercon.com (Amanda Walker)
Lines: 22

In article <1039@anasaz.UUCP>, john@anasaz.UUCP (John Moore) writes:
> [about UDP]
> I would like to know how, in practice, it can lose messages, and how
> frequently it really will do this. Question applies to both Ethernet
> LAN's, and such LAN's connected via Bridge over lower speed lines.

This depends almost entirely upon the physical configuration of the
network in question.  On a single lightly loaded Ethernet, UDP is
pretty reliable.  The more gateways you have to go through, especially
when low-speed links are involved, the higher the chances that your
datagrams will be dropped, either because of accumulated errors or
simply insufficient buffering in one of the gateways.

UDP is most useful as a cheap way to get packets around a local network
when retransmission is either unnecessary or easy to figure out how to do.
For any application that needs to work over arbitrary distances or needs
confirmation that the data actually got to the other end, TCP is probably
the way to go.

Amanda Walker
InterCon Systems Corporation
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