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53-479: 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. The advantage of using SFPs compared to fixed interfaces (e.g. modular connectors in Ethernet switches )

106-422: A Mini-GBIC by some vendors. SFP transceivers exist supporting synchronous optical networking (SONET), Gigabit Ethernet , Fibre Channel , PON , and other communications standards. At introduction, typical speeds were 1 Gbit/s for Ethernet SFPs and up to 4 Gbit/s for Fibre Channel SFP modules. In 2006, SFP+ specification brought speeds up to 10 Gbit/s and the later SFP28 iteration, introduced in 2014,

159-577: 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. 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

212-495: A QSFP port. Both a SFP-DD , which allows for 100 Gbit/s over two lanes, as well as a QSFP-DD specifications, which allows for 400 Gbit/s over eight lanes, have been published. These use a form factor which is directly backward compatible to their respective predecessors. An even larger sibling, the OSFP (Octal Small Format Pluggable) has products being released in 2022 capable of 800 Gbit/s links between network equipment. It

265-452: A backplane connector. Although the speed of plugging cannot be controlled precisely, practical considerations will provide limits that can be used to determine worst-case conditions. For a typical staggered pin design where the length difference is 0.5 mm, the elapsed time between long and short pin contact is between 25 ms and 250 ms. It is quite practical to design hot-swap circuits that can operate at that speed. As long as

318-423: A circuit that limits the inrush current to an acceptable value that cannot damage the pins nor disturb the supply voltage to adjacent slots. The pre-charge circuit might be a simple series resistor , a negative temperature coefficient (NTC) resistor, or a current-limiter circuit. Further protection can be provided by a "soft-start" circuit that provides a managed ramp-up of the internal DC supply voltages within

371-420: A component between other live components, while mechanical engagement latches, handles, or levers may be used to assist in proper insertion and removal of devices that either require large amounts of force to connect or disconnect, or to assist in the proper mating and holding together of power and communications connectors. There are two slightly differing meanings of the term hot swapping . It may refer only to

424-441: A component is removed while it is being used, the operations to that device fail and the user is responsible for retrying if necessary, although this is not usually considered to be a problem. More complex implementations may recommend but do not require that the component be shut down, with sufficient redundancy in the system to allow operation to continue if a component is removed without being shut down. In these systems hot swap

477-407: 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. 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

530-542: A device to synchronize data with a computer, and to replace faulty modules without interrupting equipment operation. A machine may have dual power supplies , each adequate to power the machine; a faulty one may be hot-swapped. Important cards such as disk controllers or host adapters may be designed with redundant paths in order for these to be replaceable in case of failure without necessitating interruption of associated computer system operation. Machines that support hot swapping need to be able to modify their operation for

583-484: A kind of hot swapping called Edit and Continue, which is supported by C# , VB.NET and C / C++ when running under a debugger. Hot swapping is the central method in live coding , where programming is an integral part of the runtime process. In general, all programming languages used in live coding, such as SuperCollider , TidalCycles , or Extempore support hot swapping. Some web-based frameworks, such as Django , support detecting module changes and reloading them on

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636-504: A set of optical network elements (ONE) connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals. An ONE may re-time, re-Amplify, re-shape ( 3R ) but it does not have to be 3R – it can be purely photonic. Unless connected by optical fibre links, it shall not be OTN. Mere functionality of switching, management, supervision shall not make it OTN, unless

689-569: 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. 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

742-450: A temporary short-circuit to ground. This can cause unwanted ground-level pulses on the signals which can disturb the operation of other hot-swap components in the system. This was a problem for early parallel SCSI disk-drives. One common design solution is to protect bussed signal pins with series diodes or resistors. CMOS buffer devices are now available with specialized inputs and outputs that minimize disturbance of bussed signals during

795-635: A thumb drive, external hard disk drive (HDD), mouse, keyboard, or printer out of a computer's USB slot or peripheral hub without ejecting it first. Most smartphones and tablets with tray-loading holders can interchange SIM cards without powering down the system. Dedicated digital cameras and camcorders usually have readily accessible memory card and battery compartments for quick changing with only minimal interruption of operation. Batteries can be cycled through by recharging reserve batteries externally while unused. Many cameras and camcorders feature an internal memory to allow capturing when no memory card

848-449: A transceiver is not working. Hot-pluggable Most desktop computer hardware , such as CPUs and memory, are only cold-pluggable. However, it is common for mid to high-end servers and mainframes to feature hot-swappable capability for hardware components, such as CPU , memory, PCIe , SATA and SAS drives. An example of hot swapping is the express ability to pull a Universal Serial Bus (USB) peripheral device, such as

901-458: Is a slightly larger version than the QSFP form factor allowing for larger power outputs. The OSFP standard was initially announced in 2016 with the 4.0 version released in 2021 allowing for 800 Gbit/s via 8× 100 Gbit/s electrical data lanes. Its proponents say a low-cost adapter will allow for backwards compatibility with QSFP modules. SFP transceivers are available with a variety of transmitter and receiver specifications, allowing users to select

954-457: 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. 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

1007-545: Is designed for speeds of 25 Gbit/s . 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 100 Gbit/s . In 2019, the closely related QSFP56 was standardized doubling the top speeds to 200 Gbit/s with products already selling from major vendors. There are inexpensive adapters allowing SFP transceivers to be placed in

1060-446: Is inserted. Hot swapping is used whenever it is desirable to change the configuration or repair a working system without interrupting its operation. It may simply be for convenience of avoiding the delay and nuisance of shutting down and then restarting complex equipment or because it is essential for equipment, such as a server , to be continuously active. Hot swapping may be used to add or remove peripherals or components, to allow

1113-421: Is normally used for regular maintenance to the computer, or to replace a broken component. Most modern hot-swap methods use a specialized connector with staggered pins, so that certain pins are certain to be connected before others. Most staggered-pin designs have ground pins longer than the others, ensuring that no sensitive circuitry is connected before there is a reliable system ground. The other pins may all be

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1166-523: 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 . The SFP replaced the larger gigabit interface converter (GBIC) in most applications, and has been referred to as

1219-492: 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

1272-455: The PCB . Hot-swappable keyboards instead have a socket in its place that allows the switch to be freely replaced without re-soldering. Due to hot-swappable keyboards being less common, they often require being custom built or bought from custom keyboard manufacturers. They can be found in a variety of sizes and layouts , including more specialized ergonomic layouts. Hot swapping can also refer to

1325-517: The XFP transceiver . 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). Modern optical SFP transceivers support standard digital diagnostics monitoring (DDM) functions. This feature is also known as digital optical monitoring (DOM). This capability allows monitoring of

1378-453: The DC power supply voltage. ESD effects can be reduced by careful design of the mechanical package around the hot-swap component, perhaps by coating it with a thin film of conductive material. Particular care must be taken when designing systems with bussed signals which are wired to more than one hot-swap component. When a hot-swap component is inserted its input and output signal pins will represent

1431-420: 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

1484-589: The SFP-DD will support legacy SFP modules and cables, and new double density products." SFP-DD uses two lanes to transmit. Currently, the following speeds are defined: 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 . Switch and router manufacturers implementing QSFP+ ports in their products frequently allow for

1537-405: The ability to add or remove hardware without powering down the system, while the system software may have to be notified by the user of the event in order to cope with it. Examples include RS-232 and lower-end SCSI devices. Some implementations require a component shutdown procedure prior to removal. This simplifies the design, but such devices are not robust in the case of component failure. If

1590-488: The ability to alter the running code of a program without needing to interrupt its execution. Interactive programming is a programming paradigm that makes extensive use of hot swapping, so the programming activity becomes part of the program flow itself. Only a few programming languages support hot swapping natively, including Pike , Lisp , Erlang , Smalltalk , Visual Basic 6 (not VB.NET ), Java and most recently Elm and Elixir . Microsoft Visual Studio supports

1643-495: 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. Note that the QSFP/QSFP+/QSFP28/QSFP56 are designed to be electrically backward compatible with SFP/SFP+/SFP28 or SFP56 respectively. Using

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1696-462: The changed configuration , either automatically on detecting the change, or by user intervention. All electrical and mechanical connections associated with hot-swapping must be designed so that neither the equipment nor the user can be harmed while hot-swapping. Other components in the system must be designed so that the removal of a hot-swappable component does not interrupt operation. Protective covering plates, shields, or bezels may be used on either

1749-430: The component. A typical sequence for a hot-swap component being plugged into a slot could be as follows: Hot-swap power circuits can now be purchased commercially in specially designed ASICs called hot-swap power managers (HSPMs). Circuitry attached to signal pins in a hot-swap component should include some protection against electrostatic discharge (ESD). This usually takes the form of clamp diodes to ground and to

1802-667: The fly. However, although the same as hotswapping for most intents and purposes, this is technically just a cache purge, triggered by a new file. This does not apply to markup and programming languages such as HTML and PHP respectively, in the general case, as these files are normally reinterpreted on each use by default. There are a few CMSes and other PHP-based frameworks (such as Drupal ) that employ caching, however. In these cases, similar abilities and exceptions apply. Hot swapping also facilitates developing systems where large amounts of data are being processed, as in entire genomes in bioinformatics algorithms. The term "HOT PLUG"

1855-552: The following line rates. The OTUk (k=1/2/2e/3/3e2/4) is an information structure into which another information structure called ODUk (k=1/2/2e/3/3e2/4) is mapped. The ODUk signal is the server layer signal for client signals. The following ODUk information structures are defined in ITU-T Recommendation G.709 At a very high level, the typical signals processed by OTN equipment at the Optical Channel layer are: A few of

1908-773: 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. SFP28 is a 25 Gbit/s interface which evolved from the 100 Gigabit Ethernet interface which is typically implemented with 4 by 25 Gbit/s data lanes. Identical in mechanical dimensions to SFP and SFP+, SFP28 implements one 28 Gbit/s lane accommodating 25 Gbit/s of data with encoding overhead. SFP28 modules exist supporting single- or multi-mode fiber connections, active optical cable and direct attach copper. The compact small form-factor pluggable ( cSFP )

1961-459: The grounds are in the corners and the power pins are near the center. Two sense pins are located in opposite corners so that fully seated detection is confirmed only when both of them are in contact with the slot. The remaining pins are used for all the other data signals. The DC power supplies to a hot-swap component are usually pre-charged by dedicated long pins that make contact before the main power pins. These pre-charge pins are protected by

2014-433: The hot-swap connector is sufficiently rigid, one of the four corner pins will always be the first to engage. For a typical two-row connector arrangement this provides four first-to-make corner pins that are usually used for grounds. Other pins near the corners can be used for functions that would also benefit from this effect, for example sensing when the connector is fully seated. This diagram illustrates good practice where

2067-445: The hot-swap operation. If all else fails, another solution is to quiesce the operation of all components during the hot-swap operation. Modern day radio transmitters (and some TV transmitters as well) use high power RF transistor power modules instead of vacuum tubes . Hot swapping power modules is not a new technology, as many of the radio transmitters manufactured in the 1930s were capable of having power tubes swapped out while

2120-462: The key functions performed on these signals are: The OTN signals at all data-rates have the same frame structure but the frame period reduces as the data-rate increases. As a result, the Time-Slot Interchange (TSI) technique of implementing SONET/SDH switch fabrics is not directly applicable to OTN switch fabrics. OTN switch fabrics are typically implemented using Packet Switch Fabrics. On

2173-688: The major difference between 8 and 16 Gbit/s Fibre Channel is the encoding method. The 64b/66b encoding used for 16 Gbit/s is a more efficient encoding mechanism than 8b/10b used for 8 Gbit/s , and allows for the data rate to double without doubling the line rate. 16GFC doesn't really use 16 Gbit/s signaling anywhere. It uses a 14. 025 Gbit/s line rate to achieve twice the throughput of 8GFC. 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. 10 Gbit/s SFP+ modules are exactly

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2226-402: The removable components or the main device itself to prevent operator contact with live powered circuitry, to provide antistatic protection for components being added or removed, or to prevent the removable components from accidentally touching and shorting out the powered components in the operating device. Additional guide slots, pins, notches, or holes may be used to aid in proper insertion of

2279-524: 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. Through the use of an active electronic adapter, SFP+ modules may be used in older equipment with XENPAK ports and X2 ports. SFP+ modules can be described as limiting or linear types; this describes

2332-827: The same length, but in some cases three pin lengths are used so that the incoming device is grounded first, data lines connected second, and power applied third, in rapid succession as the device is inserted. Pins of the same nominal length do not necessarily make contact at exactly the same time due to mechanical tolerances, and angling of the connector when inserted. At one time staggered pins were thought to be an expensive solution, but many contemporary connector families now come with staggered pins as standard; for example, they are used on all modern serial SCSI disk-drives. Specialized hot-plug power connector pins are now commercially available with repeatable DC current interruption ratings of up to 16 A. Printed circuit boards are made with staggered edge-fingers for direct hot-plugging into

2385-486: The signals are carried through optical fibre. Unlike SONET/SDH, OTN provides a mechanism to manage multiplexed wavelengths in a DWDM system. OTN was designed to provide higher throughput (currently 400G) than its predecessor SONET / SDH , which stops at 40 Gbit/s, per channel. ITU-T Recommendation G.709 is commonly called Optical Transport Network (OTN) (also called digital wrapper technology or optical channel wrapper ). As of December 2009, OTN has standardized

2438-669: The system powered on, the Nintendo Game Boy Advance and the Nintendo 64 would freeze up and could potentially become corrupt if the game cartridge was removed with the power on. Manufacturers specifically warned against such practices in the owner's manual or on the game cartridge. It was supposedly for this reason that Stop 'N' Swop was taken out of the Banjo-Kazooie series . With the Sega Genesis/Mega Drive system, it

2491-470: The transmitter is properly chosen for the conditions at the transmitting site. Power limitations: Although most contemporary video game systems can interchange games and multimedia (e.g. Blu-rays ) without powering down the system, older generations of systems varied in their support of hot-swapping capabilities. For example, whereas the Sony PlayStation and PlayStation 2 could eject a game disc with

2544-507: The transmitter was running—but this feature was not universally adopted due to the introduction of more reliable high power tubes. In the mid-1990s, several radio transmitter manufactures in the US started offering swappable high power RF transistor modules. The reintroduction of power modules has been good for the radio transmitter industry, as it has fostered innovation. Modular transmitters have proven to be more reliable than tube transmitters, when

2597-759: 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. There also exist fanout cables to adapt a single QSFP28 port to four independent 25 Gigabit Ethernet SFP28 ports (QSFP28-to-4×SFP28) as well as cables to adapt a single QSFP56 port to four independent 50 Gigabit Ethernet SFP56 ports (QSFP56-to-4×SFP56). 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

2650-415: The vendor's own modules. Third-party SFP manufacturers have introduced SFPs with EEPROMs which may be programmed to match any vendor ID. Black Black Blue 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. The SFP transceiver contains

2703-451: Was first published on May 9, 2006, and version 4.1 was published on July 6, 2009. SFP+ supports 8 Gbit/s 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 16 Gbit/s Fibre Channel, it can be used at this speed. Besides the data rate,

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2756-597: Was registered as a trademark in the United States in November 1992 to Core International, Inc. , and cancelled in May 1999. Optical Transport Network An optical transport network ( OTN ) is a digital wrapper that encapsulates frames of data, to allow multiple data sources to be sent on the same channel. This creates an optical virtual private network for each client signal. ITU-T defines an optical transport network as

2809-406: Was sometimes possible to apply cheats (such as a player having infinite lives) and other temporary software alterations to games by hot swapping cartridges, even though the cartridges were not designed to be hot swappable. Hot-swappable keyboards enable changing the switches without having to disassemble the keyboard. On standard mechanical-switch keyboards, the switch is directly soldered to

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