Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!interlan.interlan.COM!kasten
From: kasten@interlan.interlan.COM (Frank Kastenholz)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  Reliability of TCP/IP
Message-ID: <8908281553.AA01532@interlan.interlan.com>
Date: 28 Aug 89 15:53:38 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 28


TCP/IP as a suite IS reliable (or at least as reliable as the rest of the
network world:-). Where the confusion may have arisen is that IP, in and
of itself is NOT reliable. In a middle to large sized network, IP datagrams
can and ARE dropped, lost, duplicated, corrupted, misordered, etc, etc.
The TCP layer corrects for this. To quote from the TCP Spec (RFC 793):

	"This document focuses its attention primarily on ....
	computer communication requirements, especially robustness
	in the presence of communication unreliability and availability
	in the presence of congestion"

and
	"Very few assumptions are made as to the reliability of the
	communication protocols below the TCP layer. TCP assumes it can
	obtain a simple, potentially unreliable datagram service from the
	lower level protocols."

and finally, 

	"The TCP must recover from data that is damaged, lost, duplicated,
	or delivered out of order by the internet communication system."

TCP/IP is reliable. 

Cheers
Frank Kastenholz
Racal InterLan