100Base-SX between Fiber Optical Cables and Fiber Media Converters

The establishment of the 100Base-SX standard by the TIA-formally titled the TIA/EIA-785 100 Mbit/sec Physical Layer Dependent Sub-layer and 10 Mbit/sec and 100 Mbit/sec Auto-Negotiation on 850-nm Short Wavelength-opened new opportunities for users to deploy horizontal fiber. The "Short-Wavelength Fast Ethernet" specifications, as they have been called, allow users to migrate from 10 to 100 Mbits/sec over multimode fiber using 850-nm optics.

The standard supports a multimode cable distance of 300 meters-an optimum length for horizontal applications. It was based on a model that used worst-case values and assumptions, such as the use of 62.5-µm fiber with 160 MHz·km bandwidth. In reality, most 100Base-SX equipment will support a distance of 500 meters if good quality multimode fiber is in the link.

Media converters can be a crucial part of the implementation of TIA/EIA-785 and, therefore, a key component in a user's migration path to higher speeds over multimode fiber. Advances in media conversion technology, coupled with the recent release of the 785 standard, make it more realistic than ever for users to do exactly that.

Most media converters are designed to be application-specific, meaning the converter will support only one or at most two similar applications. For example, a media converter may support 10 Mbit/sec Ethernet (converting 10Base-T to 10Base-FL), 100 Mbit/sec Ethernet (100Base-TX to 100Base-FX), or 10/100 Mbit/sec Ethernet (100Base-SX, dual protocol 10/100 Mbit-sec Ethernet).

10M/100M/1000M Gigabit Media Converter

The primary reason that media converters are application-specific is the technical complexity required for each application-and the associated cost to handle multiple applications in one media-converter unit. Considering the significant differences in copper and fiber application protocols, and in optical transmitter and detectors, multiple applications can escalate the cost of a media converter.

Speeding Fiber-to-the-Desk

Take, as an example, the user who must set up a 10 Mbit/sec Ethernet link to a microcontroller on a factory floor. The nearest telecommunications room is 450 meters away. The microcontroller has a built-in Ethernet port and spare Ethernet switch ports available in the TR. The solution: Use multimode fiber and a media converter on each end of the link. The choice of media converters comes down to economics: pay $140 for two 10-Mbit/sec converters, or pay $1,800 for a do-it-all converter that supports 10, 100, and 1000 Mbit/sec Ethernet over either multimode or single mode fiber.

Single-application media converters mean a simpler product design, reduced development overhead, quicker time to market, and easier field deployment. In short, single-application drives costs down.

Sopto supplies high quality fiber media converters with reasonable price. For the newest quotes, please contact a Sopto representative by calling 86-755-36946668, or by sending an email to info@sopto.com. For more info, please browse our website.