Newsgroups: bit.listserv.big-lan
Date:         Tue, 10 Nov 1992 11:22:56 EST
From:         BIG-REQ@SUVM.BITNET
Subject:      BIG-LAN Digest, Volume 4, Number 75, Tuesday, November 10, 1992

BIG-LAN DIGEST          Tuesday, 10 November 1992      Volume 4 : Issue 75

Today's Topics:

               who is using both single & multi mode fiber
                       Re: A second annual survey?

Moderated by John Wobus, Syracuse University

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Date: Fri, 6 Nov 1992 14:49:25 -0500
From: george_loftus@brown.edu
Subject:      who is using both single & multi mode fiber

Here at Brown University we are writing our 10 Year Media Plan for Voice
and  Data Communications. This is a joint effort between the
Telecommunications Department and Computing & Information Services. My
questions relate to how other schools have dealt with deciding how much
single-mode versus how much multi-mode fiber to install. Also, has anyone
had experience with using single mode fiber for data transmission.

Five years ago, Brown installed a Northern Telecom PBX. During that
installation several runs of single mode fiber were installed between the
sites where satellite PBX switches were installed. This fiber is in service
today for voice only. Subsequently, mulitmode fiber was installed in
locations around campus where the copper voice cable plant was being
upraded. It just made sense to install fiber while the ground was open.

So, now we have dark multi-mode fiber in some parts of the campus, and
single mode (used for voice only) in other parts. Our plans are to install
an ATM backbone (within the next few years) between 4 major sites on campus
(you guessed it, right where the satellite PBX's are located). We would
then star wire adjacent portions of the campus to these major ATM switching
sites with 10-Base-FL (or FOIRL until the 10-based-FL standard is
approved). But with our current installed fiber we do not have multi mode
fiber to each of the four major sites (only 1 is multi-mode and 3 are
single mode).

Now to my questions.

We are trying to determine whether it would be cheaper to install multimode
fiber next to the single mode fiber  and connect all four major sites via
multi-mode or to use single-mode to mulit-mode converters. Has anyone used
such a conveter ? We have gotten informal pricing of approximately
$5000-$6000 per device (with a device needed at each end). Are there
devices that act as multiplexors which would allow me to tie several
multi-mode buildings to the single mode runs that are connecting the major
switching sites ?

I am basing the need to convert single mode to multimode on my limited
research which leads me to believe that there are no current data comm
standards which use single mode fiber. My understanding is that FOIRL,
FDDI, 10-Base-FL and ATM (at 155 Mbps) are all specified for multi-mode
fiber.

I feel compelled to install both single mode and multli mode fiber each
time I install cable, thus far people have agreed with me but  can not tell
me exactly why. It is purely a "hedging your bet" decision. The major
drawback I see with single mode fiber is the cost of lighting it up. My gut
feel is that the laser light sources will become cheaper (in discussions
with vendors at InterOp we found that the manufacturing cost for single
mode light sources is not much more expensive than LED's for multi-mode,
vendors just don't think the market is there yet)  and single mode will
become the fiber of choice. It will scale better with the plans for Gbit
LANs. Multi-mode already has known bandwidth limitations and with cheaper
light sources for single mode , multimode could go the way of Level 3 UTP
(remember just 2 years ago when that was the "universal cable" to install).

I invite any conversation and assistance on the topic.

Thanks.

George_Loftus@Brown.edu

George Loftus        "When all people think the same;
Brown University CIS  no one thinks very much".
Voice - 401-863-7352

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Date: Tue, 10 Nov 92 11:04:44 -0500
From: "John M. Wobus" <jmwobus@mailbox.syr.edu>
Subject:      Re: A second annual survey?

In message <9210301610.AA01349@spider.syr.EDU> I write:
>...
>This year, my choices are:
>(1) Run the same survey again.  It would be interesting to see how
> things are changing.
>(2) Run no survey--things change every year, but not THAT much.
> Every two years ought to be sufficient.
>(3) Run an improved survey.  Some people gave me great questions which
> I should have asked last year.  The best one I recall is "Which do you
> use: manageable hubs or unmanageable hubs?"  I still have the suggestions
> stashed away some where ready for this moment.
>(4) Run a completely different survey.  Find out the new and interesting
> things without repeating what we already know.
>...

I got a number of comments--specifically:
Answerer           Choice  Comment
#### ######:        3      Run same survey each year, with some tuning.
######## ########:  not 2  A survey would be well worth it.
####### #####:      3      Run an improved survey.
#### ######:        4      Run a new survey--maybe alternate years.
#### #####:         3      Run an improved survey.
##### ####:         4      Run a new survey.
##### ######:       1      Run the survey again.
### #######:        3      Run an improved survey but try not to
                            change wording.
####### ######:     3      Get rid of the dumb questions and add new and
                            improved ones.
#### #######:       3      Run a similar survey.
##### ####:         3      Run an improved survey.

I think the consensus is to improve last year's survey and run it
again.  Last year's survey itself asked for suggestions for questions
so I have a stash of them somewhere.  Now is your chance to suggest
other improvements.

My own main motivation for doing the work of running this survey is to
provide fodder for answers in the BIG-LAN FAQ Memo.  Last year's survey
questions were simplistic, but I don't think short, quick surveys like
this one can be otherwise--the usefulness of our answers will be
limited, but our necessary time-investment will be affordable.  For the
purposes of the FAQ, whose job it is to cover "frequent" questions
whether or not they are simplistic, the limited usefulness of a
question's objective answer can be explained in a paragraph or two.

Thankyou,

John Wobus
BIG-LAN Moderator
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Here are last year's questions.  Feel free to tell me which questions
to get rid of, which to definitely keep, or what to add.  Please mail
your suggestions to jmwobus@mailbox.syr.edu:

THE SURVEY WE WANT TO REPLACE:
 1. Do you administer or do you help administer a Campus Network?
 2. What campus?
 3. Approximately how many stations does your Campus Network serve?
 4. Approximately how many people are on your campus?
 5. Is your Campus Network part of the Internet?
 6. Is your Campus Network include one or more BITNET nodes?
 7. Name some router vendors whose routers you have used and recommend:
 8. Name some bridge vendors whose bridges you have used and recommend:
 9. Name some Ethernet concentrator/transceiver/repeater vendors whose
    Ethernet equipment you have used and recommend:
10. Name some Token Ring equipment vendors whose Token Ring equipment you
    have used and recommend:
11. Name some FDDI equipment vendors whose FDDI equipment you have used
    and recommend:
12. Name some PC network software vendors whose PC network software you
    have used or recommend:
13. Name some books that you have read or referenced to help administer
    your campus LAN that you would recommend:
14. Name some periodicals that you read that you would recommend to
    administrators of campus networks:
15. Name some free network software which you have used and would
    recommend:
16. Name some protocols that you use to interconnect your campus that
    you would recommend:
17. Name some commercial microcomputer network-software packages that
    you have used and would recommend:
18. Name some network management system that you use for the management
    of a campus LAN, that you recommend:
19. Name other software that you use for the management of a campus LAN
    that you recommend:
20. Name vendors of terminal servers that you use and recommend:
21. Name some vendors of network troubleshooting equipment that you use
    and would recommend:
22. Name some security products that you use to maintain security on
    your campus LAN that you recommend:
23. Name some training programs that you have attended that you would
    recommend for administrators of Campus Networks:
24. Name some conferences that you have attended that you would reco
24. Name some conferences that you have attended that you would recommend
    for administrators of Campus Networks:
25. When you build a campus network, do you tend to use bridges as opposed
    to routers?
26. If you have worked on a campus that uses mainly bridges and on a
    campus that uses mainly routers, which does your experience tell
    you is the better way to build a campus network?
27. For Internet names of nodes on a campus network that supports TCP/IP,
    do you prefer the use of subdomains?
28. If you have worked on a campus that utilizes subdomains and one that
    does not, which does your experience tell you is the better way to
    administer names in a campus network?
29. For client station's mail, which do you prefer: SMTP; TCP/IP-based
    client-server protocols (e.g. POP, POP2, etc); other LAN protocols.
30. When you install a LAN, which "Technology" (e.g. Ethernet, Token Ring)
    do you prefer?
31. If you have experience with two or more LAN technologies, which
    have you found works better?
32. Please name any other useful questions for future versions of this
    Survey:

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End of BIG-LAN Digest
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