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From: levin@sparkyfs.istc.sri.com (Larry Levin)
Newsgroups: comp.protocols.misc
Subject: Re: Realtime Protocols
Message-ID: <32683@sparkyfs.istc.sri.com>
Date: 1 Oct 90 23:46:44 GMT
References: <24594@uflorida.cis.ufl.EDU> <1990Sep30.194033.16776@hellgate.utah.edu>
Reply-To: levin@beijing.itstd.sri.com.UUCP (Larry Levin)
Distribution: usa
Organization: SRI International, Menlo Park, CA 94025
Lines: 29

In article <1990Sep30.194033.16776@hellgate.utah.edu> haas%basset.utah.edu@cs.utah.edu (Walt Haas) writes:
>In article <24594@uflorida.cis.ufl.EDU> wardc@banana () writes:
>>A friend just asked me an interesting question regarding network
>>protocols.  His company requires a "realtime" protcol.  By realtime they
>>are interested in ensuring that data arrived uncorrupted at the
>>destination within a certain period.  None of the protocols that I'm
>>aware of (TCP/IP, MAP etc.) provide this as an option.  About the only
>>suggestion I could make is to use MAP with token-ring.  Does anyone
>>know of any other protocols that might be appropriate.
>
>Actually I don't believe either MAP or token ring will qualify either.
>What you need is something based on time division.  A company called
>Applitech sells a line of Ethernet bridges using a proprietary protocol

There are alternatives to TDMA.  A timed token protocol such as that
used with 802.4 or FDDI will put a bound on response time and provide
prioritization as well.  Another possible approach that I have used is
a polled/response scheme.  This actually works quite well over any type
of lan.   Ive used this on an Ethernet to get response times down in the
10-100 millisecond range without requiring custom hardware.

By the way, I believe that MAP is still based on the 802.4 timed token
bus standard.

Larry Levin
Information Systems-Engineering Center
SRI International
Menlo Park, CA
levin@itstd.sri.com