Networks - Transceivers

Transceiver, the combination of transmitter and receiver

Optical transceivers are devices that interface network switches, router, or computers with optical fibres.

Optical transceivers are devices that transmit and receive data between network switches, firewalls, servers, and routers.

An optical transceiver has a functional circuit made up of a transmitter, receiver, a modulation chip, and an electrical input/output. The modulation chip converts input electrical signals into digital pulses of light. The transceiver then launches this optical signal into an optical fibre.

In the same way, the receiver chip converts optical signals into electrical signals which are fed into a network switch, router, or computer.

There are many different transceiver technologies including duplex, bi-directional, fixed wavelength, and tunable wavelength. There are also many different form factors including small form-factor pluggable (SFP), quadrature-SFP (QSFP), and C form-factor pluggable (CFP).

Duplex and Bidirectional (BiDi)

There are two configurations used to facilitate optical traffic in transceivers:

  • Duplex
  • Bi-directional (“BiDi”)

Duplex transceivers use two independent optical fibres to transport data, one to receive data from networking equipment, and the other to transmit data to the networking equipment.

BiDi transceivers transport optical signals of different wavelengths between network components.

BiDi transceivers use a single optical fibre to transport data bi-directionally. Typically, they enable optical signals of different wavelengths to propagate between interconnected equipment. The wavelengths are separated using dichroic beam splitters (“diplexers”) located inside the transceiver. This is known as wavelength division multiplexing (WDM).

Form factors and data rates

Typically, transceivers can be swapped in and out of network switches or routers whist they are still running without causing damage (“hot-pluggable”). Hot-pluggable transceivers have many different form factors, and each form-factor has an associated data rate.

Form Factor Data Rate(s)
SFP-(2).png SFP 1 Gb/s
100 Mb/s
SFP-(1).png SFP+ 10 Gb/s
8 Gb/s, 16 Gb/s (FC)
QSFP.png QSFP+ 40 Gb/s
CFP.png CFP 100 Gb/s
CFP2.png CFP2 100 Gb/s
CFP4.png CFP4 100 Gb/s
QSFP28.png QSFP28 100 Gb/s
CFP8.png CFP8 400 Gb/s

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