Multimode fiber to GbE

[ddrueding]

Looking for some multimode fiber to GbE media converters. I can either do standalone or stick some thingies into the ports on my 3Com Gigabit switch. One of the fibers is only about 300m long, but the other is about 1300m.

I don't work with these very often, so I'm not entirely sure where to look.

Thanks!

 

[MaxBurn]

Is the fiber already there? If so that will determine everything. Where I have had to use this before on the job it has been pretty expensive.

 

[ddrueding]

The fiber is already in place. Currently I have some standalone 100Mbps units in place, and they are operating fine. The short run is to some of our other offices, and the long run is to my offsite backup location. Both could use some more speed.

IIRC it is 62.5mm multimode fiber, 6 strand.

 

[udaman]

The fiber is already in place. Currently I have some standalone 100Mbps units in place, and they are operating fine. The short run is to some of our other offices, and the long run is to my offsite backup location. Both could use some more speed.

IIRC it is 62.5mm multimode fiber, 6 strand.

Hmm, think MB was referring to mode spec, and I'm guessing you have older OM1, which seems will be a problem to get higher speeds than 100Mbs with a longer cable run like 1300m .

I know nothing other than a quick Google :

http://en.wikipedia.org/wiki/Multi-mode_optical_fiber

The equipment used for communications over multi-mode optical fiber is much less expensive than that for single-mode optical fiber.[1] Typical transmission speed/distance limits are 100 Mbit/s for distances up to 2 km (100BASE-FX), 1 Gbit/s to 220–550 m (1000BASE-SX), and 10 Gbit/s to 300 m (10GBASE-SR).

This article reprinted from a cabling magazine (might want to check that) seems interesting, shows OM1<which is what I'm guessing you have?, restricted lengths much lower data rates depending on setup, see chart:

http://www.hyperline.com/info/cabling_02-09_1/

I guess Infiniband implementations will be too expensive?

http://en.wikipedia.org/wiki/InfiniBand

5yrs from now, can hope Light Peak becomes standardized I/O, will simplify a lot for short distance I/O, households...did not know standard optical is restricted to wide bends to avoid light leakage.:

http://en.wikipedia.org/wiki/Light_Peak

In July 2007, Corning Incorporated announced a new optical fiber known as ClearCurve that uses nanostructure reflectors to keep light trapped within the fiber even when bent around small-radius curves.[2][3] Corning's original market for ClearCurve was fiber to the home market, especially in large housing units and apartments where the installation of fiber into the individual units would otherwise be difficult. ClearCurve can be pulled through the same sorts of conduits as the existing copper, but is physically smaller and carries much more bandwidth. Even the single-mode version, with a single carrier frequency, offers maximum data rates of 25 Gbps.[4]

 

[ddrueding]

Thanks for the bits, Uda. Looks like I'll only be able to do Gb on the short run. Looking into getting a pair of 3Com 1000BASE-SX SFP Transceivers (Part# 3CSFP91) to plug into the GbE switches on either side.

 

[Pradeep]

This shows some of the limits of the 62.5 multimode:

http://www.tequipment.net/pdf/AdvancedFiberSolutions/BWT.pdf

Do you have line of sight to the more remote location? There's some nice line of sight gear that can be easily configured to use your existing network link in case of degradation (heavy fog etc). Alternatively millimeter wave radio which presumably doesn't degrade.

http://www.lightpointe.com/products/default.cfm

 

[blakerwry]

The fiber is already in place. Currently I have some standalone 100Mbps units in place, and they are operating fine. The short run is to some of our other offices, and the long run is to my offsite backup location. Both could use some more speed.

IIRC it is 62.5mm multimode fiber, 6 strand.

DD, are you sure that long run is multimode - and not single mode?

Multimode 50 or 62.5micron fiber is typically only good for up to 300-500m using 1000BaseSX (the typical fiber standard for ethernet switches).

To go farther, ethernet switches use single mode (10u) and 1000BaseLX (aka LH in older cisco gear), up to several miles. In my experience, even older ATM based OC3/OC12 technologies follows the same conventions with single/multimode use as well.

Because of this, It seems a bit odd anyone would ever run a 62.5u fiber longer than what is supported by typical data standards. Of course, SONET, CDWM or other technologies may be able to utilize 62.5u fiber over longer distances, it just won't be gigabit or ethernet.

 

[blakerwry]

btw, I would definitely recommend the "thingies into the ports", assuming you can get them that will support your fiber. SFP's and GBICs act as a native switchport - allowing the switch to configure and collect data linke any other switchport.

Often, the use of stand alone transparent bridges result in hidden duplex mismatches, discarded frames, or link state problems (one switch sees the link up while the other switch is actually down). The also add another point of failure, something else to UPS, etc.

 

[ddrueding]

Thanks all for the info. I'll inspect the existing fiber on Tuesday, and come back with better information.