SFP vs SFP+ vs XFP: Definition, Introduction and Difference

SFP Definition  and Introduction

What is SFP? Small form-factor pluggable  (SFP) is a general specification for a new generation of optical modular  transceivers. The devices are designed with small form factor (SFF) connectors  and offer high speed on both transmitter and receiver sides, and are commonly used  for both telecommunication and data communications applications nowadays. SFP optical  transceivers have two features: high physical compactness and hot-pluggable. And  the form factor and electrical interface are specified by a multi-source  agreement (MSA). The SFP is also a popular industry format jointly developed  and supported by many network component vendors. Generally SFP modules  interface a network device motherboard (for a switch, router, media converter  or similar device) to a fiber optic or copper networking cable. As its  definition shows, small size is another feature of SFP. Due to its smaller  size, SFP obsolesces the formerly ubiquitous gigabit interface converter  (GBIC); the SFP is sometimes referred to as a Mini-GBIC.

SFP transceivers are designed to support SONET, gigabit Ethernet, Fibre Channel, and other communications standards. Although it is not mentioned in any  official specification document, - the maximum data rate of the original SFP  standard is 5 gigabits per second. Because SFP modules can be easily  interchanged, electro-optical or fiber optic networks can be upgraded and  maintained more conveniently than has been the case with traditional  soldered-in modules. Rather than replacing an entire circuit board containing  several soldered-in modules, a single module can be removed and replaced for  repair or upgrading. This can result in a substantial cost savings, both in  maintenance and in upgrading efforts.

SFP modules are commonly available in  several different categories:
- 1 to 2.5 Gbit/s multi-mode fiber, LC  connector, with black or beige extraction lever
SX - 850 nm, for a maximum of 550 m at 1.25  Gbit/s (gigabit Ethernet) or 150m at 4.25 Gbit/s (Fibre Channel)
- 1 to 2.5 Gbit/s single-mode fiber, LC  connector, with blue extraction lever
LX - 1310 nm, for distances up to 10 km
EX - 1310 nm, for distances up to 40 km
ZX - 1550 nm, for distances up to 80 km  (depending on fiber path loss), with green extraction lever (see GLC-ZX-SM1)
EZX - 1550 nm, for distances up to 160 km  (depending on fiber path loss)
BX - 1490 nm/1310 nm, Single Fiber Bi-Directional  Gigabit SFP Transceivers, paired as BS-U and BS-D for Uplink and Downlink  respectively, also for distances up to 10 km.[5][6] 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)
SFSW – Single Fiber Single Wavelength  transceivers, for bi-directional traffic on a single fiber. Coupled with CWDM,  these double the traffic density of fiber links.
CWDM and DWDM transceivers at various  wavelengths achieving various maximum distances
- 1 Gbit/s for copper twisted pair cabling, 8P8C (RJ-45) connector
1000BASE-T - these modules incorporate  significant interface circuitry and can only be used for gigabit Ethernet, as  that is the interface they implement. They are not compatible with (or rather:  do not have equivalents for) Fiber channel or SONET. Unlike non-SFP, copper  1000BASE-T ports integrated into most routers and switches, 1000BASE-T SFPs  usually cannot operate at 100BASE-TX speeds.
- 100 Mbit/s copper and optical - some  vendors have shipped 100 Mbit/s 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 1 Gbit/s SFPs.

SFP+  Definition and Introduction

The enhanced small form-factor pluggable  (SFP+) is an enhanced version of the SFP that supports data rates up to 16 Gbps.  Just like SFP, SFP+ is also a popular industry format supported by many network  component vendors.

SFP+ supports 8 Gbps Fibre Channel, 10  Gigabit Ethernet and Optical Transport Network standard OTU2. Although the SFP+ standard does not include mention of 16G Fibre Channel it can be used at this  speed. Besides the data rate, the big difference between 8G Fibre Channel and 16G Fibre Channel is the encoding method. 64b/66b encoding used for 16G is a  more efficient encoding mechanism than 8b/10b used for 8G, and allows for the  data rate to double without doubling the line rate. The result is the 14.025  Gbit/s line rate for 16G Fibre Channel.

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. SFP+ also introduces Direct Attach for connecting two SFP+ ports  without dedicated transceivers.

XFP  Definition and Introduction

The XFP (10 Gigabit Small Form Factor Pluggable) is a standard for transceivers for high-speed computer network and  telecommunication links that use optical fiber.

XFP modules are hot-swappable and  protocol-independent. They typically operate at near-infrared wavelengths (colors) of 850 nm, 1310 nm or 1550 nm. Principal applications include 10 Gigabit Ethernet, 10 Gbit/s Fibre Channel, synchronous optical networking (SONET) at OC-192 rates, synchronous optical networking STM-64, 10 Gbit/s  Optical Transport Network (OTN) OTU-2, and parallel optics links. They can  operate over a single wavelength or use dense wavelength-division multiplexing  techniques. They include digital diagnostics that provide management that were added to the SFF-8472 standard. XFP modules use an LC fiber connector type to achieve  higher density.

XFP 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, for example, multi-mode fiber or single-mode  fiber. XFP optical modules are commonly available in several different  categories:
SR - 850 nm, for a maximum transmission distance  of 300 m
LR - 1310 nm, for distances up to 10 km
ER - 1550 nm, for distances up to 40 km
ZR - 1550 nm, for distances up to 80 km

SFP+  Definition and Introduction

The enhanced small form-factor pluggable  (SFP+) is an enhanced version of the SFP that supports data rates up to 16 Gbps.  Just like SFP, SFP+ is also a popular industry format supported by many network  component vendors.

SFP+ supports 8 Gbps Fibre Channel, 10  Gigabit Ethernet and Optical Transport Network standard OTU2. Although the SFP+ standard does not include mention of 16G Fibre Channel it can be used at this  speed. Besides the data rate, the big difference between 8G Fibre Channel and 16G Fibre Channel is the encoding method. 64b/66b encoding used for 16G is a  more efficient encoding mechanism than 8b/10b used for 8G, and allows for the  data rate to double without doubling the line rate. The result is the 14.025  Gbit/s line rate for 16G Fibre Channel.

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. SFP+ also introduces Direct Attach for connecting two SFP+ ports  without dedicated transceivers.

XFP  Definition and Introduction

The XFP (10 Gigabit Small Form Factor Pluggable) is a standard for transceivers for high-speed computer network and  telecommunication links that use optical fiber.

XFP modules are hot-swappable and  protocol-independent. They typically operate at near-infrared wavelengths (colors) of 850 nm, 1310 nm or 1550 nm. Principal applications include 10 Gigabit Ethernet, 10 Gbit/s Fibre Channel, synchronous optical networking (SONET) at OC-192 rates, synchronous optical networking STM-64, 10 Gbit/s  Optical Transport Network (OTN) OTU-2, and parallel optics links. They can  operate over a single wavelength or use dense wavelength-division multiplexing  techniques. They include digital diagnostics that provide management that were added to the SFF-8472 standard. XFP modules use an LC fiber connector type to achieve  higher density.

XFP 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, for example, multi-mode fiber or single-mode  fiber. XFP optical modules are commonly available in several different  categories:
SR - 850 nm, for a maximum transmission distance  of 300 m
LR - 1310 nm, for distances up to 10 km
ER - 1550 nm, for distances up to 40 km
ZR - 1550 nm, for distances up to 80 km

SFP vs SFP+ vs XFP Comparison

Form Factors

SFP

SFP+

XFP

Stands for

Small Form-factor Pluggable

Enhanced Small Form-factor Pluggable

10 Gigabit Small Form Factor Pluggable

Data rate

155M/622M/1.25G/2.5G/3G/4.25Gb/s

6G/8.5G/10Gb/s

10Gb/s

Terms

Dual fiber

DWDM

CWDM

Single Fiber/WDM

Dual fiber

DWDM

CWDM

Single Fiber/WDM

Dual fiber

DWDM

CWDM

Single Fiber/WDM

Distance

300m/2km/

100km/120km/150km

60km/80km/

20km/40km/

10km/15km/

220m/300m/

60km/80km

20km/40km/

2km/10km/

220m/300m/

120km

60km/80km/

20km/40km/

2km/10km/

Wavelengths

850nm/1310nm/1550nm

ITU17~ITU61

1270nm-1610nm

310nm/1490nm/1550nm

220m/300m/

60km/80km/120km

20km/40km/

2km/10km/

850nm/1310nm/1550nm

ITU17~ITU61

1270nm-1610nm

1270nm/1330nm

SFP vs SFP+ vs CFP: Differences and Similarities

SFP vs SFP+: It is simple to understand the difference  between SFP and SFP+, as SFP+ is an upgrade vision of SFP. SFP usually support low  transmission speed like 1.25Gbit/s, 2.5Gbit/s and 4.25 Gbit/s while SFP+  supports higher data rates up to 10 Gbit/s. Although both SFP and SFP+ have the  same size and appearance, they are in different standard which SFP is based on  IEEE802.3 and SFF-8472 while SFP+ is based on SFF-8431. And apparently, the  SFP+ modules are more expensive than SFP modules.

SFP+ vs XFP: In comparison to earlier XFP modules, SFP+  modules leave more circuitry to be implemented on the host board instead of  inside the module. The size of SFP+ is smaller than XFP, thus it moves some  functions to motherboard, including signal modulation function, MAC, CDR and  EDC. XFP is based on the standard of XFP MSA while SFP+ is compliance with the  protocol of IEEE 802.3ae, SFF-8431, SFF-8432.

6/17/2016 3:12:46 AM

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