CWDM SFP Overview

What is CWDM SFP

Coarse wavelength division multiplexing (CWDM) is a kind of wavelength division multiplexing (WDM) technology which combines multiple signals on laser beams along the fibre. Its system utilizes non-stabilized lasers along broadband filters channel spacing of 20 nm, allowing channels up to 18. It is a cost-efficient solution in telecoms or enterprise networks. This technology can integrate with transceiver modules especially small form-factor pluggable (SFP) modules. With CWDM technology, SFP modules can have different wavelengths assigned to them from 1270 nm and 1610 nm, meeting different requirements. Those SFP modules which use CWDM technology are called CWDM SFP modules. CWDM SFP modules are hot-swappable transceiver components that are used to connect fibre cables and switches.

Introduction to Cisco CWDM SFP

Cisco CWDM SFPs are the most popular compact CWDM SFP transceivers used in communications for both telecommunication and data communications. Those transceivers modules can plug into standard receptacles in Cisco routers and switches and convert Gigabit Ethernet electrical signals into a single-mode fibre-optic (SMF) interface. They can even use different wavelengths to transmit and receive signals, making fibre to fibre configuration possible. The following picture shows how CWDM SFP makes a point-to-point link. By using different channels, four channels can be transported over a single fibre strand through CWDM SFP, building a point-to-point connection.CWDM SFP

As above mentioned, CWDM SFP modules have different wavelengths from 1470 nm to 1610 nm. Cisco CWDM SFP modules have eight wavelengths in that region. Different colour markings are used to identify the wavelength to which the Gigabit Ethernet channel is mapped. The following table lists the specific colours for different wavelengths.

CWDM SFP wavelengths and color coding

How to Install CWDM SFP
To install CWDM SFP, you should know the following details.
  • Step1: Remove the CWDM SFP module from its protective packing, and verify the model of CWDM SFP. (CWDM SFP module can be identified by its label which lists the SFP module and the wavelength or by its colour bar on the bale clasp.)
  • Step2: Verify that the bale clasp on the front of the SFP module is closed before inserting the SFP module.
  • Step3: Align the CWDM SFP module in front the slot opening, slide the SFP module into the slot, and verify that whether the connect on the module snaps into place in the rear of the slot.

Note: The dust plugs can protect the CWDM SFP module optical ports and the cable connectors from contamination. You can only remove them from the optical bore of the CWDM or from the fibre optic cable when you are ready to use the module to connect the cable.

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