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Multi-source agreements (MSAs) between different equipment vendors specify guidelines for electrical and optical interfaces, mechanical dimensions and electro-magnetic specification of a transceiver. The equipment vendors follow these MSA defined values for designing their systems to ensure interoperability between interface modules.
The form-factor or the MSA-type is needed so that the transceiver can mechanically & electrically fit into a given switch, router etc. Transceiver MSAs define mechanical form factors including electric interface as well as power consumption and cable connector types. There are various MSA types: SFP, SFP+, XFP, CFP, CFP2, CFP4, QSFP and so on.
Protocol and Data rate
A protocol basically helps with the connection between two network devices. It is important to know which protocol and data rate the switch or router supports. There are various protocols such as Ethernet, Fiber Channel, InfiniBand, SONET/SDH, CPRI and so on. Each of these protocols supports their own data rates. For example Gigabit Ethernet can range from 1Gb/s to 100Gb/s while Fiber Channel ranges from 1GFC (1.0625Gb/s) to 16GFC (14.025Gb/s).
The transceiver power budget is the difference between transmitter launch power and receiver sensitivity and has to be 2-3dB larger (Margin) than the measured link loss. If the link loss cannot be measured it has to be calculated. Therefore transmission distance [km], number of ODFs, patches and passive optical components (Muxes) have to be known. Common values for power budget are <10, 14, 20, 24, 28, >30dB.
Transport Media and Wavelength
Transport media can be single-mode fiber, multimode fiber and also copper. The single-mode fiber based standard transceivers can have a transmission distance of 5km to 120km, thanks to single-mode fiber’s lower attenuation. While the multimode transceivers are defined from 150m to 5km. The difference in transmission distance also arises from different transmitter power, receiver sensitivity and the wavelength in operation.
The transceivers functioning in wide 1310nm and 1550nm are called “grey” while those functioning in one of the grids falling in CWDM or DWDM grid are called “colored”. The transceivers can also be simplex/bi-di which transmit and receive the data in a single fiber but different wavelengths. While the duplex on the other hand, work with dual fiber.
Finding the correct transceiver for the switch and network might look like a mammoth challenge, but knowing above discussed parameters beforehand helps you narrow it down to a couple of transceivers.