Small Form-factor Pluggable
Template:Short description Template:Redirect Template:Use American English Template:Use mdy dates
Small Form-factor Pluggable (SFP) is a compact, hot-pluggable network interface module format used for both telecommunication and data communications applications. An SFP interface on networking hardware is a modular slot for a media-specific transceiver, such as for a fiber-optic cable or a copper cable.<ref name="pcmag"/> The advantage of using SFPs compared to fixed interfaces (e.g. modular connectors in Ethernet switches) is that individual ports can be equipped with different types of transceivers as required, with the majority including optical line terminals, network cards, switches and routers.
The form factor and electrical interface are specified by a multi-source agreement (MSA) under the auspices of the Small Form Factor Committee.<ref name="sfpmsa"/> The SFP replaced the larger gigabit interface converter (GBIC) in most applications, and has been referred to as a Mini-GBIC by some vendors.<ref name="Cisco MGBSX1"/>
SFP transceivers exist supporting synchronous optical networking (SONET), Gigabit Ethernet, Fibre Channel, PON, and other communications standards. At introduction, typical speeds were Template:Nowrap for Ethernet SFPs and up to Template:Nowrap for Fibre Channel SFP modules.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In 2006, SFP+ specification brought speeds up to Template:Nowrap and the later SFP28 iteration, introduced in 2014,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> is designed for speeds of Template:Nowrap.<ref name="snia"/>
A slightly larger sibling is the four-lane Quad Small Form-factor Pluggable (QSFP). The additional lanes allow for speeds 4 times their corresponding SFP. In 2014, the QSFP28 variant was published allowing speeds up to Template:Nowrap.<ref name="sff-8665"/> In 2019, the closely related QSFP56 was standardized<ref name="sff-8636r2.9.2draft" /> doubling the top speeds to Template:Nowrap with products already selling from major vendors.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> There are inexpensive adapters allowing SFP transceivers to be placed in a QSFP port.
Both a SFP-DD,<ref name="SFP-DD MSA"/> which allows for Template:Nowrap over two lanes, as well as a QSFP-DD<ref name="QSFP-DD MSA"/> specifications, which allows for Template:Nowrap over eight lanes, have been published.<ref name="Lightwave" /> These use a form factor which is directly backward compatible to their respective predecessors.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
An even larger sibling, the Octal Small Format Pluggable (OSFP), had products released in 2022<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> capable of Template:Nowrap links between network equipment. It is a slightly larger version than the QSFP form factor allowing for larger power outputs. The OSFP standard was initially announced in 2016<ref name="OSFP MSA" /> with the 4.0 version released in 2021 allowing for Template:Nowrap via 8×Template:Nowrap electrical data lanes.<ref>Template:Cite press release</ref> Its proponents say a low-cost adapter will allow for backwards compatibility with QSFP modules.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
SFP typesEdit
SFP transceivers are available with a variety of transmitter and receiver specifications, allowing users to select the appropriate transceiver for each link to provide the required optical or electrical reach over the available media type (e.g. twisted pair or twinaxial copper cables, multi-mode or single-mode fiber cables). Transceivers are also designated by their transmission speed. SFP modules are commonly available in several different categories.
| Name | Nominal speed |
Lanes | Standard | Introduced | Backward-compatible | PHY interface | Connector | |
|---|---|---|---|---|---|---|---|---|
| SFP | Template:Nowrap | 1 | SFF INF-8074i | 2001-05-01 | Template:N/a | MII | LC, RJ45 | |
| SFP | Template:Nowrap | 1 | SFF INF-8074i | 2001-05-01 | Template:Nowrap SFP* | SGMII | LC, RJ45 | |
| cSFP | Template:Nowrap | 2 | LC | |||||
| SFP+ | Template:Nowrap | 1 | SFF SFF-8431 4.1 | 2009-07-06 | SFP | XGMII | LC, RJ45 | |
| SFP28 | Template:Nowrap | 1 | SFF SFF-8402 | 2014-09-13 | SFP, SFP+ | LC | ||
| SFP56 | Template:Nowrap | 1 | SFP, SFP+, SFP28 | LC | ||||
| SFP-DD | Template:Nowrap | 2 | SFP-DD MSA<ref name=sfp-dd.spec/> | 2018-01-26 | SFP, SFP+, SFP28, SFP56 | LC | ||
| SFP112 | Template:Nowrap | 1 | 2018-01-26 | SFP, SFP+, SFP28, SFP56 | LC | |||
| SFP-DD112 | Template:Nowrap | 2 | 2018-01-26 | SFP, SFP+, SFP28, SFP56, SFP-DD, SFP112 | LC | |||
| QSFP types | ||||||||
| QSFP | Template:Nowrap | 4 | SFF INF-8438 | 2006-11-01 | Template:N/a | GMII | ||
| QSFP+ | Template:Nowrap | 4 | SFF SFF-8436 | 2012-04-01 | Template:N/a | XGMII | LC, MTP/MPO | |
| QSFP28 | Template:Nowrap | 2 | SFF SFF-8665 | 2014-09-13 | QSFP+ | LC | ||
| QSFP28 | Template:Nowrap | 4 | SFF SFF-8665 | 2014-09-13 | QSFP+ | LC, Template:Nowrap | ||
| QSFP56 | Template:Nowrap | 4 | SFF SFF-8665 | 2015-06-29 | QSFP+, QSFP28 | LC, Template:Nowrap | ||
| QSFP112 | Template:Nowrap | 4 | SFF SFF-8665 | 2015-06-29 | QSFP+, QSFP28, QSFP56 | LC, Template:Nowrap | ||
| QSFP-DD | Template:Nowrap | 8 | SFF INF-8628 | 2016-06-27 | citation | CitationClass=web
}}</ref> QSFP56 |
LC, Template:Nowrap | |
Note that the QSFP/QSFP+/QSFP28/QSFP56 are designed to be electrically backward compatible with SFP/SFP+/SFP28 or SFP56 respectively. Using a simple adapter or a special direct attached cable it is possible to connect those interfaces together using just one lane instead of four provided by the QSFP/QSFP+/QSFP28/QSFP56 form factor. The same applies to the QSFP-DD form factor with 8 lanes which can work downgraded to 4/2/1 lanes.
Template:Nowrap SFPEdit
- Multi-mode fiber, LC connector, with Template:Fontcolour or Template:Fontcolour color coding
- SXTemplate:Snd850 nm, for a maximum of 550 m
- Multi-mode fiber, LC connector, with Template:Fontcolour color coding
- FX Template:Snd1300 nm, for a distance up to 5 km.
- LFX (name dependent on manufacturer)Template:Snd1310 nm, for a distance up to 5 km.
- Single-mode fiber, LC connector, with Template:Fontcolour color coding
- LXTemplate:Snd1310 nm, for distances up to 10 km
- EXTemplate:Snd1310 nm, for distances up to 40 km
- Single-mode fiber, LC connector, with Template:Fontcolour color coding
- ZXTemplate:Snd1550 nm, for distances up to 80 km, (depending on fiber path loss)
- EZXTemplate:Snd1550 nm, for distances up to 160 km (depending on fiber path loss)
- Single-mode fiber, LC connector, Bi-Directional, with Template:Fontcolour and Template:Fontcolour color coding
- BX (officially BX10)Template:Snd1550 nm/1310 nm, Single Fiber Bi-Directional 100 Mbit SFP Transceivers, paired as BX-U (Template:Fontcolour) and BX-D (Template:Fontcolour) for uplink and downlink respectively, also for distances up to 10 km. Variations of bidirectional SFPs are also manufactured which higher transmit power versions with link length capabilities up to 40 km.
- Copper twisted-pair cabling, 8P8C (RJ-45) connector
- 100BASE-TXTemplate:Snd for distances up to 100m.
Template:Nowrap SFPEdit
- 1 to 1.Template:Nowrap multi-mode fiber, LC connector, with black or beige extraction lever<ref name="sfpmsa"/>
- SXTemplate:Snd850 nm, for a maximum of 550 m at 1.Template:Nowrap (gigabit Ethernet). Other multi-mode SFP applications support even higher rates at shorter distances.<ref>Template:Citation</ref>
- 1 to 1.Template:Nowrap multi-mode fiber, LC connector, extraction lever colors not standardized
- SX+/MX/LSX/LX (name dependent on manufacturer)Template:Snd1310 nm, for a distance up to 2 km.<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref> Not compatible with SX or 100BASE-FX. Based on LX but engineered to work with a multi-mode fiber using a standard multi-mode patch cable rather than a mode-conditioning cable commonly used to adapt LX to multi-mode.
- 1 to 2.Template:Nowrap single-mode fiber, LC connector, with blue extraction lever<ref name="sfpmsa"/>
- LXTemplate:Snd1310 nm, for distances up to 10 km (originally, LX just covered 5 km and LX10 for 10 km followed later)
- EXTemplate:Snd1310 nm, for distances up to 40 km
- ZXTemplate:Snd1550 nm, for distances up to 80 km (depending on fiber path loss), with green extraction lever (see GLC-ZX-SM1)
- EZXTemplate:Snd1550 nm, for distances up to 160 km (depending on fiber path loss)
- BX (officially BX10)Template:Snd1490 nm/1310 nm, Single Fiber Bi-Directional Gigabit SFP Transceivers, paired as BX-U and BX-D for uplink and downlink respectively, also for distances up to 10 km.<ref>Template:Citation</ref><ref>Template:Citation</ref> Variations of bidirectional SFPs are also manufactured which use 1550 nm in one direction, and higher transmit power versions with link length capabilities up to 80 km.
- 1550 nm 40 km (XD), 80 km (ZX), 120 km (EX or EZX)
- SFSWTemplate:Sndsingle-fiber single-wavelength transceivers, for bi-directional traffic on a single fiber. Coupled with CWDM, these double the traffic density of fiber links.<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
- Coarse wavelength-division multiplexing (CWDM) and dense wavelength-division multiplexing (DWDM) transceivers at various wavelengths achieve various maximum distances. CWDM and DWDM transceivers usually support link distances of 40, 80 and 120 km.
- Template:Nowrap for copper twisted-pair cabling, 8P8C (RJ-45) connector
- 1000BASE-TTemplate:Sndthese modules incorporate significant interface circuitry for Physical Coding Sublayer recoding<ref>Template:Citation</ref> and can be used only for gigabit Ethernet because of the specific line code. They are not compatible with (or rather: do not have equivalents for) Fibre Channel or SONET. Unlike most non-SFP, copper 1000BASE-T ports integrated into most routers and switches, 1000BASE-T SFPs usually cannot operate at 100BASE-TX speeds.
- Template:Nowrap copper and opticalTemplate:Sndsome vendors have shipped Template:Nowrap limited SFPs for fiber-to-the-home applications and drop-in replacement of legacy 100BASE-FX circuits. These are relatively uncommon and can be easily confused with Template:Nowrap SFPs.<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref>
- Although it is not mentioned in any official specification document the maximum data rate of the original SFP standard is Template:Nowrap.<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref> This was eventually used by both 4GFC Fibre Channel and the DDR Infiniband especially in its four-lane QSFP form.
- In recent years,Template:When SFP transceivers have been created that will allow [[2.5GBASE-T and 5GBASE-T|2.Template:Nowrap and Template:Nowrap Ethernet]] speeds with SFPs with 2.5GBASE-T<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref> and 5GBASE-T.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Template:AnchorTemplate:Nowrap SFP+Edit
The SFP+ (enhanced small form-factor pluggable) is an enhanced version of the SFP that supports data rates up to 16 Gbit/s. The SFP+ specification was first published on May 9, 2006, and version 4.1 was published on July 6, 2009.<ref name="spec">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> SFP+ supports Template:Nowrap Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. It is a popular industry format supported by many network component vendors. Although the SFP+ standard does not include mention of Template:Nowrap Fibre Channel, it can be used at this speed.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Besides the data rate, the major difference between 8 and Template:Nowrap Fibre Channel is the encoding method. The 64b/66b encoding used for Template:Nowrap is a more efficient encoding mechanism than 8b/10b used for Template:Nowrap, and allows for the data rate to double without doubling the line rate. 16GFC doesn't really use Template:Nowrap signaling anywhere. It uses a 14.Template:Nowrap line rate to achieve twice the throughput of 8GFC.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
SFP+ also introduces direct attach for connecting two SFP+ ports without dedicated transceivers. Direct attach cables (DAC) exist in passive (up to 7 m), active (up to 15 m), and active optical (AOC, up to 100 m) variants.
Template:Nowrap SFP+ modules are exactly the same dimensions as regular SFPs, allowing the equipment manufacturer to re-use existing physical designs for 24 and 48-port switches and modular line cards. In comparison to earlier XENPAK or XFP modules, SFP+ modules leave more circuitry to be implemented on the host board instead of inside the module.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Through the use of an active electronic adapter, SFP+ modules may be used in older equipment with XENPAK ports <ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and X2 ports.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
SFP+ modules can be described as limiting or linear types; this describes the functionality of the inbuilt electronics. Limiting SFP+ modules include a signal amplifier to re-shape the (degraded) received signal whereas linear ones do not. Linear modules are mainly used with the low bandwidth standards such as 10GBASE-LRM; otherwise, limiting modules are preferred.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Template:Nowrap SFP28Edit
SFP28 is a Template:Nowrap interface which evolved from the 100 Gigabit Ethernet interface which is typically implemented with 4 by Template:Nowrap data lanes. Identical in mechanical dimensions to SFP and SFP+, SFP28 implements one Template:Nowrap lane<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> accommodating Template:Nowrap of data with encoding overhead.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
SFP28 modules exist supporting single-<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> or multi-mode<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> fiber connections, active optical cable<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and direct attach copper.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
cSFPEdit
The compact small form-factor pluggable (cSFP) is a version of SFP with the same mechanical form factor allowing two independent bidirectional channels per port. It is used primarily to increase port density and decrease fiber usage per port.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
SFP-DDEdit
The small form-factor pluggable double density (SFP-DD) multi-source agreement is a standard published in 2019 for doubling port density. According to the SFD-DD MSA website: "Network equipment based on the SFP-DD will support legacy SFP modules and cables, and new double density products."<ref>http://sfp-dd.com/ SFP-DD MSA</ref> SFP-DD uses two lanes to transmit.
Currently, the following speeds are defined:
- SFP112: Template:Val using PAM4 on a single pair (not double density)<ref name=sfp-dd.spec>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref>
- SFP-DD: Template:Val using PAM4 and Template:Val using NRZ<ref name=sfp-dd.spec/>
- SFP-DD112: Template:Val using PAM4<ref name=sfp-dd.spec/>
- QSFP112: Template:Val (4 × Template:Val)<ref name=qsfp-dd.msa>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref>
- QSFP-DD: Template:Val/Template:Val (8 × Template:Val and 8 × Template:Val)<ref>SFF INF-8628</ref>
- QSFP-DD800 (formerly QSFP-DD112): Template:Val (8 × Template:Val)<ref name=qsfp-dd.msa/>
- QSFP-DD1600 (Draft) Template:Val<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref>
QSFPEdit
Quad Small Form-factor Pluggable (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 multi-mode or single-mode fiber.
- Template:Nowrap
- The original QSFP document specified four channels carrying Gigabit Ethernet, 4GFC (FiberChannel), or DDR InfiniBand.<ref name="inf8438">{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref>
- Template:Nowrap (QSFP+)
- QSFP+ is an evolution of QSFP to support four Template:Nowrap channels carrying 10 Gigabit Ethernet, 10GFC FiberChannel, or QDR InfiniBand.<ref name="sff8436">{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref> The 4 channels can also be combined into a single 40 Gigabit Ethernet link.
- Template:Nowrap (QSFP14)
- The QSFP14 standard is designed to carry FDR InfiniBand, SAS-3<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref> or 16G Fibre Channel.
- Template:Nowrap (QSFP28)
- The QSFP28 standard<ref name="sff-8665" /> is designed to carry 100 Gigabit Ethernet, EDR InfiniBand, or 32G Fibre Channel. Sometimes this transceiver type is also referred to as QSFP100 or 100G QSFP<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref> for sake of simplicity.
- Template:Nowrap (QSFP56)
- QSFP56 is designed to carry 200 Gigabit Ethernet, HDR InfiniBand, or 64G Fibre Channel. The biggest enhancement is that QSFP56 uses four-level pulse-amplitude modulation (PAM-4) instead of non-return-to-zero (NRZ). It uses the same physical specifications as QSFP28 (SFF-8665), with electrical specifications from SFF-8024<ref name="sff-8024">{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref> and revision 2.10a of SFF-8636.<ref name="sff-8636r2.9.2draft">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Sometimes this transceiver type is referred to as 200G QSFP<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> for sake of simplicity.
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. For example, a typical 24-port QSFP+ 1U switch would be able to service 96x10GbE connections.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> There also exist fanout cables to adapt a single QSFP28 port to four independent 25 Gigabit Ethernet SFP28 ports (QSFP28-to-4×SFP28)<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> as well as cables to adapt a single QSFP56 port to four independent 50 Gigabit Ethernet SFP56 ports (QSFP56-to-4×SFP56).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
ApplicationsEdit
SFP sockets are found in Ethernet switches, routers, firewalls and network interface cards. They are used in Fibre Channel host adapters and storage equipment. Because of their low cost, low profile, and ability to provide a connection to different types of optical fiber, SFP provides such equipment with enhanced flexibility.
SFP sockets and transceivers are also used for long-distance serial digital interface (SDI) transmission.<ref>Template:Cite book</ref>
StandardizationEdit
The SFP transceiver is not standardized by any official standards body, but rather is specified by a multi-source agreement (MSA) among competing manufacturers. The SFP was designed after the GBIC interface, and allows greater port density (number of transceivers per given area) than the GBIC, which is why SFP is also known as mini-GBIC.
However, as a practical matter, some networking equipment manufacturers engage in vendor lock-in practices whereby they deliberately break compatibility with generic SFPs by adding a check in the device's firmware that will enable only the vendor's own modules.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Third-party SFP manufacturers have introduced SFPs with EEPROMs which may be programmed to match any vendor ID.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Color coding of SFPEdit
Color coding of SFPEdit
| Color | Standard | Media | Wavelength | Notes | |
|---|---|---|---|---|---|
Black |
INF-8074 | Multimode | 850 nm | ||
| Template:Nowrap | INF-8074 | Multimode | 850 nm | ||
Black |
INF-8074 | Multimode | 1300 nm | ||
Blue |
INF-8074 | Singlemode | 1310 nm | ||
| Template:Nowrap | Template:Partial | Singlemode | 1310 nm | citation | CitationClass=web
}}</ref> |
| Template:Nowrap | Template:Partial | Singlemode | 1550 nm | Used on 100BASE-ZE | |
| Template:Nowrap | Template:Partial | Singlemode | 1550 nm | Used on 10GBASE-ER | |
| Template:Nowrap | Template:Partial | Singlemode | 1550 nm | Used on 10GBASE-ZR |
===Color coding of CWDM SFP <ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> ===
| Color | Standard | Wavelength | Notes |
|---|---|---|---|
| Template:Nowrap | 1270 nm | ||
| Template:Nowrap | 1290 nm | ||
| Template:Nowrap | 1310 nm | ||
| Template:Nowrap | 1330 nm | ||
| Template:Nowrap | 1350 nm | ||
| Template:Nowrap | 1370 nm | ||
| Template:Nowrap | 1390 nm | ||
| Template:Nowrap | 1410 nm | ||
| Template:Nowrap | 1430 nm | ||
| Template:Nowrap | 1450 nm | ||
| Template:Nowrap | 1470 nm | ||
| Template:Nowrap | 1490 nm | ||
| Template:Nowrap | 1510 nm | ||
| Template:Nowrap | 1530 nm | ||
| Template:Nowrap | 1550 nm | ||
| Template:Nowrap | 1570 nm | ||
| Template:Nowrap | 1590 nm | ||
| Template:Nowrap | 1610 nm |
Color coding of BiDi SFPEdit
| Name | Standard | Side A Color TX | Side A wavelength TX | Side B Color TX | Side B wavelength TX | Notes |
|---|---|---|---|---|---|---|
| 1000BASE-BX | Template:Nowrap | 1310 nm | Template:Nowrap | 1490 nm | ||
| 1000BASE-BX | Template:Nowrap | 1310 nm | Template:Nowrap | 1550 nm | ||
| 10GBASE-BX 25GBASE-BX |
Template:Nowrap | 1270 nm | Template:Nowrap | 1330 nm | ||
| 10GBASE-BX | Template:Nowrap | 1490 nm | Template:Nowrap | 1550 nm |
Color coding of QSFPEdit
| Color | Standard | Wavelength | Multiplexing | Notes |
|---|---|---|---|---|
| Template:Nowrap | INF-8438 | 850 nm | No | |
| Template:Nowrap | INF-8438 | 1310 nm | No | |
| Template:Nowrap | INF-8438 | 1550 nm | No |
SignalsEdit
SFP transceivers are right-handed: From their perspective, they transmit on the right and receive on the left. When looking into the optical connectors, transmission comes from the left and reception is on the right.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The SFP transceiver contains a printed circuit board with an edge connector with 20 pads that mate on the rear with the SFP electrical connector in the host system. The QSFP has 38 pads including 4 high-speed transmit data pairs and 4 high-speed receive data pairs.<ref name="inf8438"/><ref name="sff8436"/>
| Pad | Name | Function |
|---|---|---|
| 1 | VeeT | Transmitter ground |
| 2 | Tx_Fault | Transmitter fault indication |
| 3 | Tx_Disable | Optical output disabled when high |
| 4 | SDA | 2-wire serial interface data line (using the CMOS EEPROM protocol defined for the ATMEL AT24C01A/02/04 family<ref>INF-8074i B4</ref>) |
| 5 | SCL | 2-wire serial interface clock |
| 6 | Mod_ABS | Module absent, connection to VeeT or VeeR in the module indicates module presence to host |
| 7 | RS0 | Rate select 0 |
| 8 | Rx_LOS | Receiver loss of signal indication |
| 9 | RS1 | Rate select 1 |
| 10 | VeeR | Receiver ground |
| 11 | VeeR | Receiver ground |
| 12 | RD- | Inverted received data |
| 13 | RD+ | Received data |
| 14 | VeeR | Receiver ground |
| 15 | VccR | Receiver power (3.3 V, max. 300 mA) |
| 16 | VccT | Transmitter power (3.3 V, max. 300 mA) |
| 17 | VeeT | Transmitter ground |
| 18 | TD+ | Transmit data |
| 19 | TD- | Inverted transmit data |
| 20 | VeeT | Transmitter ground |
| Pad | Name | Function |
|---|---|---|
| 1 | GND | Ground |
| 2 | Tx2n | Transmitter inverted data input |
| 3 | Tx2p | Transmitter non-inverted data input |
| 4 | GND | Ground |
| 5 | Tx4n | Transmitter inverted data input |
| 6 | Tx4p | Transmitter non-inverted data input |
| 7 | GND | Ground |
| 8 | ModSelL | Module select |
| 9 | ResetL | Module reset |
| 10 | Vcc-Rx | +3.3 V receiver power supply |
| 11 | SCL | Two-wire serial interface clock |
| 12 | SDA | Two-wire serial interface data |
| 13 | GND | Ground |
| 14 | Rx3p | Receiver non-inverted data output |
| 15 | Rx3n | Receiver inverted data output |
| 16 | GND | Ground |
| 17 | Rx1p | Receiver non-inverted data output |
| 18 | Rx1n | Receiver inverted data output |
| 19 | GND | Ground |
| 20 | GND | Ground |
| 21 | Rx2n | Receiver inverted data output |
| 22 | Rx2p | Receiver non-inverted data output |
| 23 | GND | Ground |
| 24 | Rx4n | Receiver inverted data output |
| 25 | Rx4p | Receiver non-inverted data output |
| 26 | GND | Ground |
| 27 | ModPrsL | Module present |
| 28 | IntL | Interrupt |
| 29 | Vcc-Tx | +3.3 V transmitter power supply |
| 30 | Vcc1 | +3.3 V power supply |
| 31 | LPMode | Low power mode |
| 32 | GND | Ground |
| 33 | Tx3p | Transmitter non-inverted data input |
| 34 | Tx3n | Transmitter inverted data input |
| 35 | GND | Ground |
| 36 | Tx1p | Transmitter non-inverted data input |
| 37 | Tx1n | Transmitter inverted data input |
| 38 | GND | Ground |
Mechanical dimensionsEdit
The physical dimensions of the SFP transceiver (and its subsequent faster variants) are narrower than the later QSFP counterparts, which allows for SFP transceivers to be placed in QSFP ports via an inexpensive adapter. Both are smaller than the XFP transceiver.
| SFP<ref name="sfpmsa" /> | QSFP<ref name="inf8438"/> | XFP<ref name="xfpspec">{{#invoke:citation/CS1|citation | CitationClass=web
}}</ref> | ||||
|---|---|---|---|---|---|---|---|
| mm | in | mm | in | mm | in | ||
| Height | Template:Convert | Template:Convert | Template:Convert | ||||
| Width | Template:Convert | Template:Convert | Template:Convert | ||||
| Depth | Template:Convert | Template:Convert | Template:Convert | ||||
EEPROM informationEdit
The SFP MSA defines a 256-byte memory map into an EEPROM describing the transceiver's capabilities, standard interfaces, manufacturer, and other information, which is accessible over a serial I²C interface at the 8-bit address 0b1010000X (0xA0).<ref>SFF INF-8438i 6.2.2 Management Interface Timing Specification</ref>
Digital diagnostics monitoringEdit
Modern optical SFP transceivers support standard digital diagnostics monitoring (DDM) functions.<ref>Template:Citation</ref> This feature is also known as digital optical monitoring (DOM). This capability allows monitoring of the SFP operating parameters in real time. Parameters include optical output power, optical input power, temperature, laser bias current, and transceiver supply voltage. In network equipment, this information is typically made available via Simple Network Management Protocol (SNMP). A DDM interface allows end users to display diagnostics data and alarms for optical fiber transceivers and can be used to diagnose why a transceiver is not working.