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QSFP 40 Gb Transceiver

The Quad Small Form-factor Pluggable (QSFP) is a compact, hot-pluggable transceiver used for data communications applications. The form factor and electrical interface are specified by a multi-source agreement (MSA) under the auspices of the Small Form Factor Committee. It interfaces networking hardware to a fiber optic cable or active or passive electrical copper connection. It is an industry format jointly developed and supported by many network component vendors, allowing data rates from 4x10 Gbit/s.[1] The format specification is evolving to enable higher data rates; as of May 2013, highest possible rate is 4x28 Gbit/s (also known as QSFP28).[2]


QSFP transceivers are available with a variety of transmitter and receiver types, allowing users to select the appropriate transceiver for each link to provide the required optical reach over the available optical fiber type (e.g. multi-mode fiber or single-mode fiber). QSFP modules are commonly available in several different categories:

4 x 4 Gbit/s QSFP[edit]

The original QSFP document specified four channels carrying Gigabit Ethernet, 4GFC (FiberChannel), or DDR InfiniBand.[3]

4 x 10 Gbit/s QSFP+[edit]

QSFP+ is an evolution of QSFP to support four 10 Gbit/sec channels carrying 10 Gigabit Ethernet, 10GFC FiberChannel, or QDR InfiniBand.[4] The 4 channels can also be combined into a single 40 Gigabit Ethernet link.

4 x 14 Gbit/s QSFP+ (QSFP14)[edit]

The QSFP14 standard is designed to carry FDR InfiniBand and SAS-3.[5]

4 x 28 Gbit/s QSFP+ (QSFP28)[edit]

The QSFP28 standard is designed to carry 100 Gigabit Ethernet or EDR InfiniBand.[6] This transceiver type is also used with direct-attach breakout cables to adapt a single 100GbE port to four independent 25 gigabit ethernet ports (QSFP28-to-4x-SFP28).[7] Sometimes this transceiver type is also referred to as "QSFP100" or "100G QSFP" [8] for sake of simplicty.


Switch and router manufacturers implementing QSFP ports in their products frequently allow for the use of a single QSFP port as four independent 10 gigabit ethernet connections, greatly increasing port density in a 1U height 24-port switch (24 40Gb ports x 4 = 96 10GbE).[9][10][11]


QSFP has 38 pins with 4 high-speed TX pairs (CML-I) and 4 high-speed RX pairs (CML-O).[12][13]

See also[edit]


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