The difference between optical modules (SFP GBIC XFP SFP+)

The continuous expansion of the transmission capacity of the communication network trunk line and the continuous improvement of the speed have made optical fiber communication the main transmission method of modern information networks. There are more and more types of optical transceiver modules required as one of the core optoelectronic devices, and the requirements are getting higher and higher, and the complexity is also developing at an alarming rate. The rapid increase of optical transceiver modules has led to diversity, and related technologies need to be continuously developed to meet such application requirements.

Let's first understand what is an optical transceiver module,

1. Definition of optical transceiver module

The integrated optical transceiver module is composed of optoelectronic devices, functional circuits and optical interfaces. The optoelectronic devices include two parts: transmitting and receiving. The transmitting part is: the input electrical signal with a certain code rate is processed by the internal driver chip to drive the semiconductor laser (LD) or light emitting diode (LED) to emit a modulated optical signal of the corresponding rate. The output optical signal power remains stable. The receiving part is: the optical signal with a certain code rate is converted into an electrical signal by the light detection diode after being input into the module. After the preamplifier, the electrical signal of the corresponding code rate is output, and the output signal is generally PECL level. At the same time, when the input optical power is less than a certain value, an alarm signal will be output.

Second, the optical transceiver module classification

According to the rate: 100Base (100M), 1000Base (Gigabit), 10GE for Ethernet applications; 155M, 622M, 2.5G, 10G for SDH applications.

According to the package: 1×9, SFF, SFP, GBIC, XENPAK, XFP, various packages are shown in Figures 1 to 6.

1×9 package – welding type optical module, the general speed is not higher than gigabit, and SC interface is mostly used

SFF package – Welding small package optical modules, the general speed is not higher than gigabit, and LC interface is mostly used. SFF (SmallForm.Factor) small package optical module adopts advanced precision optics and circuit integration technology, the size is only half of ordinary duplex SC (1X9) optical fiber transceiver module, in the same space can double the number of optical ports, can Increase line port density and reduce system cost per port. And because the SFF small package module adopts the MT-RJ interface similar to the copper network, the size is the same as that of the common computer network copper interface, which is conducive to the transition of the existing copper-based network equipment to the higher-speed optical fiber network. To meet the dramatic increase in network bandwidth demand.

GBIC package – hot-swappable Gigabit interface optical module with SC interface. GBIC is the abbreviation of GigaBitrateInterfaceConverter, which is an interface device that converts gigabit electrical signals into optical signals. The GBIC is designed to be hot-swappable. GBIC is an interchangeable product that complies with international standards. Gigabit switches designed with GBIC interface occupy a large market share in the market due to their flexible interchangeability.

SFP package – hot-swappable small package module, currently the highest data rate can reach 4G, mostly using LC interface. SFP is the abbreviation of SMALLFORM.PLUGGABLE, which can be simply understood as an upgraded version of GBIC. The volume of the SFP module is reduced by half compared to the GBIC module, and more than double the number of ports can be configured on the same panel. The other functions of the SFP module are basically the same as those of the GBIC. Some switch manufacturers call the SFP module a miniaturized GBIC (MINI-GBIC)

XENPAK package – used in 10 Gigabit Ethernet, using SC interface

XFP package – 10G optical module, can be used in 10 Gigabit Ethernet, SONET and other systems, mostly using LC interface

Do some interpretation of the above concepts. The first thing to know is that GBIC (GigaStackGigabitInterfaceConverter) is a general-purpose, low-cost Gigabit Ethernet stacking module, which can provide high-speed connections between Cisco switches, which can not only build high-density port stacking, but also realize integration with servers or thousands of The connection of the megabit backbone is for the transition from Fast Ethernet to Gigabit Ethernet. GBIC modules are divided into two categories, one is the GBIC module used for ordinary cascading, and the other is the GBIC module dedicated to stacking.

The second is the SFP small pluggable transceiver module, which can be simply understood as an upgraded version of GBIC.

The SFP module (the volume is half that of the GBIC module, and more than double the number of ports can be configured on the same panel. Since the SFP module is basically the same as the GBIC in function, it is also called a miniaturized GBIC (Mini GBIC) by some switch manufacturers. ‐GBIC). Because it can be directly inserted on the circuit board, it saves space and time on the package.

At present, SFP+ modules commonly used in 10G networks, SFP is SmallForm-factor Pluggables. For the difference between SFP and SFP+, one is used in 10G networks, while SFP supports Gigabit and 100M speeds. For SFP+, it is the latest pluggable fiber optic module form factor for 10Gbps Ethernet and 8.5Gbps FibreChannel systems.

SFP+ has a more compact form factor than X2 and XFP packages and consumes less than 1W. In addition, it offers higher mounting density than current 10Gbps devices. A newer design has made SFP+ the same size as the SFP (Small Form Factor Pluggable) industry standard, which is geared towards data rates up to 4Gbps.

The XFP that everyone is familiar with is the 10GigabitSmallFormFactorPluggable 10 Gigabit Ethernet optical transceiver. XFP is a serial module used in the 10GbE field and is a next-generation optical module. However, with the constant discussion on whether to use 10G directly or transition to 4G first and the introduction of 4G network standards and products, XFP seems to have suffered some blows.

Remark:

PECL is positive emitter coupled logic with fairly high speed, differential signaling.

Bit error rate (BER: biterrorratio) is an indicator to measure the accuracy of data transmission within a specified time. Bit error rate=errors in transmission/total number of codes transmitted*100%. If there is a bit error, there is a bit error rate.

The difference between SFP+ and SFP and XFP

The 10G module has undergone development from 300Pin, XENPAK, X2, and XFP, and finally realized the transmission of 10G signals with the same size as SFP, which is SFP+. With its advantages of miniaturization and low cost, SFP meets the high-density optical module requirements of equipment. Since the standard was pushed in 2002, it has replaced XFP and became the mainstream of the 10G market in 2010.

Advantages of SFP+ optical modules:

1. SFP+ has a more compact form factor than X2 and XFP packages (same size as SFP);

2. It can be directly connected with the same type of XFP, X2, XENPAK;

3. The cost is lower than that of XFP, X2 and XENPAK products.

The difference between SFP+ and SFP:

1. SFP and SFP+ have the same dimensions;

2. SFP protocol specification: IEEE802.3, SFF-8472;

The difference between SFP+ and XFP:

1. Both SFP+ and XFP are 10G fiber optic modules, and can communicate with other types of 10G modules;

2. SFP+ is smaller in size than XFP;

3. Because of its smaller size, SFP+ moves the signal modulation function, serial/deserializer, MAC, clock and data recovery (CDR), and electronic dispersion compensation (EDC) functions from the module to the motherboard card;

4. The protocol that XFP complies with: XFPMSA protocol;

5. Protocols compliant with SFP+: IEEE802.3ae, SFF-8431, SFF-8432;

6. SFP+ is a more mainstream design.

7.SFP+ protocol specification: IEEE802.3ae, SFF-8431, SFF-8432.