The optical modules are important components in networking, and specifying the right modules can heavily influence overall system performance. There issues you should consider when choosing a fiber optic module are listed below.
1.The Most Important Design Considerations – Density and Form Factor
You can buy transceivers that plug into the faceplate, or you can buy embedded, mid-board optical modules. You may want to choose a mid-board module if you want more density at the faceplate or for greater electrical performance because you’re able to put the module closer to the IC on the circuit board and minimize electrical losses.
The choices range from the small form-factor pluggable (SFP) module at 1Gb/s up to the CFP module at 100Gb/s. Some parallel optical modules have incoming signal rates of 25Gb/s, and there are mid-board modules that use 12 lanes of 25Gb/s to deliver 300Gb/s. You can also choose the QSFP module with four channels of 10 Gigabits each, or the SFP+ module as a single 10Gb/s lane.
3.The Length of the Optical Signal to Travel
This leads to a decision between an Active Optical Cable (AOC) and a transceiver, and using single-mode or multi-mode transceiver. An AOC is a single unit that consists of two transceivers and a piece of optical fiber that joins them. With a transceiver, you take a passive fiber cable and connect it to the transceiver. For distances less than 20 to 30 meters, an AOC is probably the less expensive choice. If you want the signal to go more than 30 meters, you’d more likely use the transceiver with a passive fiber cable. Single-mode transceiver used for long reach transmission and multi-mode transceiver for short reach.
4.Heat Transfer and Power Consumption
Every optical module generates heat, but some modules run considerably cooler than others. Engineers need to assess how much power is being consumed and how much heat is being generated, as well as whether the system has the capability to remove that heat. With cooler optical modules, the equipment saves direct power but also can have a substantial impact on reducing air conditioning costs for the data center.
Transceivers are designed by a multi-vendor consortium with open specifications. It’s usually preferable to match your SFP to your switch vendor (I.E. a Cisco SFP in a Cisco switch), but you can work around that if you’re willing to risk your support/warranty to save a few bucks on transceiver costs.
Buy from a reputable third party dealer, and you get samples and guarantees. I’ve saved tens of thousands of dollars buying third party optics, and the failure rate is precisely the same as with vendor optics in my experience. The better third party transceivers are typically put together on the same manufacturing lines as the vendor branded ones.
By considering form factor, density, reach, bit rate, standards compliance, heat transfer, Network installers can properly evaluate optical modules and specify the right one for the job.