Tuesday, May 8, 2012

The Distances of your Approved Cisco Optics


The Distances of your Approved Cisco Optics:
GLC-SX-MM, SFP-GE-S, GLC-SX-MMD, GLC-SX-MM-RGD
GLC-LH-SM, SFP-GE-L, GLC-LH-SMD, GLC-LH-SM-RGD

We have been getting a lot of questions recently about the true maximum distances of our optics and wanted to spend some time going over the technical details. It seems some vendors have been touting a 1 km distance on their Multi-Mode Optics, but that is not always the case.

Technically, and like some our competitors would suggest, our 1GB Multi-Mode Optics (Like a GLC-SX-MM, SFP-GE-S, GLC-SX-MMD, GLC-SX-MM-RGD) can achieve a distance of 1 km. However, it depends entirely on the quality of your fiber. To reach 1 km you would need to use laser-optimized 50 µM multimode fiber cabling. Which, as many of our data centers would attest to is more than rare; most people aren't running a mile of laser-optimized multimode fiber. If you are, then by all means our 1GB Multi-mode products for Cisco and even Juniper, Brocade, etc are for you. But more often than not, the following information will be more accurate:
"The 1000BASE-SX SFP, compatible with the IEEE 802.3z 1000BASE-SX standard, operates on legacy 50 μm multimode fiber links up to 550 m and on 62.5 μm Fiber Distributed Data Interface (FDDI)-grade multimode fibers up to 220 m."
For the LH (GLC-LH-SM, SFP-GE-L, GLC-LH-SMD, GLC-LH-SM-RGD):
"The 1000BASE-LX/LH SFP, compatible with the IEEE 802.3z 1000BASE-LX standard, operates on standard single-mode fiber-optic link spans of up to 10 km and up to 550 m on any multimode fibers. When used over legacy multimode fiber type, the transmitter should be coupled through a mode conditioning patch cable."
That being said, most transceivers will operate effectively at 10-12% further distances than stated in our data sheets...but that will always be contingent on the quality of your cabling.

For questions, please don't hesitate to call us. We are always available: 800.590.9535.