On Dec 23, 2003, at 3:05 PM, Eric Ebner wrote:
> Sorry I didn't get back to you right away, My current full time job is
> caring for my 4 month old now that I am back from 15 months of active
> duty
> guards. I hope the below helps:
>
>> Hmm, this stuff was installed along time ago before my time here and I
>> know very little about fiber.
>>
{ snipped - misc. discussion }
>>
>> I dont know how many fibers are in each wire. Is there some marking on
>> the wire I can look for that might tell me? Its orange :) hehe
>
> Yes, fiber is marked similarly to copper fiber. There should be OFxx
> where
> the OF is, yes you guessed it Optical Fiber and xx is the type of
> fiber such
> as NP for Nonconductive Plenum or CR for Conductive Riser to name a
> couple.
> There should be more numbers/letters after this that will tell you how
> many
> strands, the manufacture, distance in meters or feet, UL
> certification, and
> sometimes some other cryptic numbers (batch or production, etc).
>
> Email me the markings and I will try to make sense of them for you.
>
>>
>> All I know is that there is 4 physical pieces running under the alley.
>> Currently we are only using 2 of the wires, 1 pair. I think they work
>> in
>> pairs? One for send and one for receive?! Is this what you are calling
>> multimode?
>
> O.K. It looks like you have 4 strand fiber running between your
> buildings.
> It is common practice to install extra fiber as the cost of installing
> far
> out ways the cost of fiber. In a basic fiber network you have two
> pairs.
> One send and one receive. In more complex fiber networks you will have
> primary and secondary pairs or failover pairs to create redundancy.
> The
> difference in single and multimode is cost, distance, and core size.
> Single
> mode is smaller in diameter (core size, not necessarily cable size),
> Is used
> for long distances, and is cheap. Multimode fiber has a larger core
> size to
> allow for several different frequencies of lasers to transmit at the
> same
> time. This allows for higher throughput and can be somewhat compared
> to
> multiplexing of voice communications. Multimode is great for
> intra-campus
> backbones and allows you to transmit several network segments (or
> greater
> bandwidth) over a single strand of fiber.
a minor nit, but MM fiber is actually larger in diameter to utilize
lesser grade optics on the ends. quite often the drivers on MM gear
are tuned LED/laser diodes as opposed to tuned lasers. the throughput
on MM fiber is not greater than over SM fiber and in practice you're
going to find that MM is used primarily in enterprise/lab applications
while in the service provider domain you're going to run primarily SM
with various flavors of optics on the ends.
99.9% of the time if the fiber is orange in color, it's multimode,
i.e.: the cheap stuff. the interesting thing and what's going to cause
you the most pain and/or frustration is the ends. it sounds like you
have ST ends (these look like BNC bayonets), these have fallen out of
fashion over the years in favor of the SC or SFP and in very high
bandwidth applications (10G+) xenpack optics and such.
setting that aside for the moment, you might try and find yourself a
pair of ST (MM w/the appropriate gender) to 1000BT media converters for
your project at hand. these will likely not be cheap but i haven't
seen a GE interface that has ST ends, ever. maybe they have them on
some older GE NICs or something but i can't recall an ST GE interface
offhand.
if you can't find an MM-ST-> 1000BT media converter you might see if
you can get someone to reterm the ends. there are some fairly
reasonably priced MM fiber termination kits out there and the self
aligning assemblies and such make this process far less daunting than
it used to be.
alternatively you might try finding a an ST (female) ->SC patch and
seeing if you can make that work happily with your switches. i would
be careful about this given that your loss budget might be rather tight
and i have no idea offhand what the losses incurred w/ST connectors to
SC connectors would be.
getting back to some of the comments that were made relative to SM vs.
MM. SM (the yellow fiber) is not the cheap stuff, it's the better of
the 2 and has much better loss budgets and is used primarily in service
provider and/or long distance applications.
MM does not provide the ability to run multiple lambda's (optical
wavelengths) over the fiber and as stated previously is typically used
with lower grade optics. SM in conjunction with wave division
multiplexing (WDM) which comes in a few different flavors DWDM (dense
wave division multiplexing), CWDM (coarse wave division multiplexing)
enables the use of multiple wavelengths over a single fiber pair and is
typically used in long-haul applications where fiber capacity is a
precious resource or in applications where running new fiber is
problematic and there's a desire to get more out of the SM that's
already in the ground.
>> I am told the other pair are backups. But if we could bond the two or
>> use both, we should just use them since they are run and unused. Seems
>> silly to just leave them sit there.
>
> If you use your backups you will network yourself into a corner as you
> will
> become dependant on fiber that is there to CYA. I would not do it.
>>
>> I am trying to learn more about this stuff. If anyone has any links or
>> other source of info that would be great.
if you google for optical networking primers and such you might find
some good starting points.
{snipped - misc. discussion}
>>> Here is an option that is just really an upgrade from what you are
>>> currently
>>> using:
>>> http://www.transition.com/products/mcon_platform/standalone/gigabit/
>>> index.ht
>>> m
>>>
>>> You may want to see if you can push multimode over your fiber. If
>>> you need
>>> more bandwidth a upgrade from single to multi sometimes is the
>>> ticket,
>>> however can be expensive.
>>>
>>> How many fibers are in you wire? Two? Four? You may also want to
>>> look into
>>> segmenting your network, taking the computers that talk to each
>>> other the
>>> most at each building and placing them on a separate segment.
>>>
>>> Just some thoughts, let me know if you want more
>>>> We have fiber running between our 2 office buildings. On each end
>>>> of the
>>>> fiber we have one of these devices to convert to ethernet
>>>> http://www.cdw.com/shop/products/default.aspx?ProductID=247614
>>>>
>>>> Basically it looks like a fiber (BNC connections) to RJ-45
>>>> converter.
>>>>
>>>> We are pretty sure the fiber should support 1000base with no
>>>> problems.
>>>> So I am looking for a drop in replacement for the 100base converter
>>>> units. Or some local consultant or company we could get out here to
>>>> put
>>>> new ends on the fiber for a non-drop in replacement converter.
>>>>
>>>> Other suggestions and comments welcome.
{snipped - misc .signatures}
--
steve ulrich sulrich at botwerks.org
PGP: 8D0B 0EE9 E700 A6CF ABA7 AE5F 4FD4 07C9 133B FAFC
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