Fiber and 10 Gig Optics

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A few days ago I found myself in a discussion surrounding connecting two switch chassis together.  The other engineers were talking about the different optic types and I realized I didn’t know as much about 10 gig optics as I thought I did.  So here’s a quick run down on fiber and 10 gig optics.

Multimode Fiber
-Also referred to as ‘OM’ type cable
-Less expensive than single mode (‘OS’) fiber
-Several variants common today (OM1, OM2, OM3, OM4)
-OM1 and OM2 are orange in color and suitable for gigabit speeds
-OM3 and OM4 are aqua in color and suitable for 10 gigabit speeds
-OM1 has a core size of 62.5 microns
-OM2 has a core size of 50 microns
-OM3 has a core size of 50 microns and is laser optimized
-OM4 has a core size of 50 microns and is laser optimized
-Wider cores allow you use less precise light sources such as LEDs
-Typically uses 850nm or 1300nm light sources (LEDs and Lasers)

Single mode Fiber
-Also referred to as ‘OS’ type cable
-Allow for a single ‘mode’ (ray of light)
-Generally yellow in color
-A couple of variants common today (OS1, OS2)
-Core is between 8 to 10 microns
-Can support distances of several thousand kilometers
-Requires laser light sources that are in the 1270nm to 1625nm range

10 Gig Optic Standards
10GBaseT – Uses standard Ethernet cabling.  Cat6a or 7
10GBaseSR – Uses multimode fiber pairs.  Max of 300m with OM3
10GBaseLX4 – Uses 4 different 2.5Gbps laser on different CWDM wavelengths.  Only available in X2 or Xenpak because of the size of all 4 lasers in a single module.  Original option to allow 10gig over older MMF fiber (not laser optimized fiber). 
10GBaseLRM – Same as the LX4 but uses EDC rather than 4 individual lasers.  Uses 1310nm lasers.  Can reach as far as 220m on OM1,2,and 3 fiber.
10GBaseLR – 10km over OS fiber.  There is no minimum distance so this type of optic can be used for short runs as well.
10GBaseER – 40km over OS fiber.  Links less than 20km require the signal to be attenuated as to not damage the receiving optic. 
10GBaseZR – 80km over OS fiber.  Significant attenuation required for runs shorter than 80km links.  Not actually a IEEE standard
10GBaseLW – Same as LR optics with the additional ability of being able to interface directly with OC192 transport.

10 Gig Interface types
There are a variety of different interfaces available for 10 gig interfaces.







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