Why are we fixated on Multimode fiber for high bandwidth communication?

David Hubbard dhubbard at dino.hostasaurus.com
Tue Dec 31 19:11:35 UTC 2013

My guess would be it's due to existing cable plants.  I've worked at a
number of places that have tons of multimode fiber run everywhere.  If
you can re-terminate and re-use, even if inefficiently, it often beats
the time and expense required to run new fiber, especially if it's a
place that pulling cable may involve trade unions; that gets very
expensive to pull what could be a not so expensive cable one or two
hundred meters.

-----Original Message-----
From: eric clark [mailto:cabenth at gmail.com] 
Sent: Tuesday, December 31, 2013 2:01 PM
To: NANOG list
Subject: Why are we fixated on Multimode fiber for high bandwidth

I've been working with 40 gig for a few years. When I first ordered a
switch, one of the first publicly available with full 40 gig, I was
appalled that I was going to have to use 4 pair of multimode fiber for
each of my connections. I had planned on using single mode because I can
do that with 1 pair.

Even today, we're still looking at MM fiber instead of SM, even with the
horrendous limitations and cost issues of MM. For instance, if you need
to go 301 meters or more, you've got to go OM4 which  is very expensive.
You have to lay 4 times the number of pairs as SM and when we move to
100G, it'll be even worse because they're still doing things in
6,12,etc... SM can do 100G easily, up to 1K with the lower grade fiber,
so in the SM 100G world, you'd be installing 1/12 the strands as you
would in multi mode. I just can't figure where this makes sense....

I am aware that single mode has more expensive optics, and I know how
much they cost when I first looked at this, but if this were the
standard, that price would drop enormously.

Anyone know why the industry has their head stuck on MultiMode?

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