Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!pasteur!ames!zodiac!joyce!milk10!levin
From: levin@milk10.uucp (Larry Levin)
Newsgroups: comp.protocols.iso
Subject: Re: ISDN and OSI relationship
Message-ID: <22155@joyce.istc.sri.com>
Date: 16 Jun 89 00:58:16 GMT
References: <1989Jun15.160207.18925@gpu.utcs.utoronto.ca>
Sender: news@joyce.istc.sri.com
Reply-To: levin@milk10.UUCP (Larry Levin)
Organization: SRI International, Menlo Park CA
Lines: 36

In article <1989Jun15.160207.18925@gpu.utcs.utoronto.ca> craig@gpu.utcs.utoronto.ca (Craig Hubley) writes:
>......  I am interested specifically in connecting private OSI LANs
>to common-carrier ISDN WANs.  I have *no interest* in implementation details
>save those directly relevant to application design.
>
  Frankly I do not think that ISDN is an acceptable bridge media
between LANs.  The problem is lack of bandwidth in ISDN (as opposed to
B-ISDN, the broadband standard) as well as regulatory issues, although
the regulations may differ outside the US.  The first question you
need to ask is if a single 64 Kbps B channel is sufficient for your
inter-LAN traffic.  If all you send is E-mail the answer is probably
yes.  If you try to run a diskless workstation off a file server the
answer is no.  In theory you could use multiple B channels for a
single bridge.  This can be done but the bridge has to transfer each
individual packet over a specific link since splitting the packet may
result in corruption due to differing transmission delays on each
channel.  I dont know of any bridges on the market to this at this
time.  I do recall a company in the Chicago area that sells an "ISDN"
bridge.  the target application in this case is to allow a single PC
or workstation to use a single B channel as if it was an extended
AUI drop-cable.
  As to the regulatory side, take a look at the tarif for T-1 versus a
Basic or Primary ISDN circuit. I admit I dont know the numbers but I
here that T-1 is considered a bargin these days.

  Two final points: In regards to you original question on OSI vs
ISDN,  see "ISDN Technology, Concepts, and Applications" by P.J.
Kuehn, Springer-Verlang Lecture notes in Computer Science, Vol 248.
In regards my response, I expect a number of folks on the net,
especially at the BOCs and Bell Labs have actually tested some of
these assumptions.  If they have opinions or experience contrary to
mine I look forward to reading about it here.

Larry Levin
SRI International
---- My opinions, love em or leave em ---