Category Archives: Optical Transceiver Solution

SFP Connector vs SFP+ Connector vs SFP28 Connector

SFP (Small Form-factor Pluggable) module connector with various data speed rate is one of the major optical transceivers used for data communication. With ever-increasing demand for faster speed and higher density, the SFP connectors have experienced several generations of update for the signal speed capability as well as port density, from the original SFP to SFP+ and then to the new SFP28 type. The compatibility of these connecting ports is the pain point for many subscribers in data communication transmission. So what’s the similarities and differences between them and are these module connectors compatible with each other when plugged into switches? SFP28 vs SFP+ vs SFP connector, which one should you choose? This paper will give you the answer.

What Is SFP Connector?

Specified by a multi-source agreement (MSA), SFP connector was first introduced in early 2000 and designed to replace the previous gigabit interface converter (GBIC) connector in fiber optic and Ethernet high-speed networking systems. Based on the IEEE 802.3, SFF-8472 protocol specification, SFP module connectors has the ability to handle up to 4.25Gb/s with greater port density than the GBIC, which is why SFP is also known as mini GBIC. This allowed it to quickly become the connector of choice for system administrators who liked the idea of being able to significantly increase their output per rack. The SFP connectors can support Gigabit Ethernet, Fibre Channel, Synchronous Optical Network (SONET) and other communication standards.

What Is SFP+ Connector?

To cater the need for faster transmission speed, the SFP+ (or SFP10) was introduced in 2006, as an extension of the SFP connector. Based on IEEE802.3ae, SFF-8431, and SFF-8432 protocol specifications, the SFP+ is designed to support data rates up to 10Gb/s. Compared with its predecessor SFP, the newly SFP+ can support Fibre Channel, 10GbE, SONET, OTN, and other communication standards. The SFP+ is similar in size to the SFP connector. And the primary difference between an SFP and a SFP+ is their transmission speed. It is noticeable that SFP/SFP+ are both copper and optical.

SFP Connector

SFP28 Connector–The Third Generation of SFP Connector

As the third generation of SFP interconnect systems, the SFP28 (Small Form-Factor Pluggable 28) is designed for 25G performance specified by the IEEE 802.3by. The SFP28 connector delivers increased bandwidth, superior impedance control with less crosstalk compared to the SFP10. SFP28 can be sorted into SFP28 SFP-25G-SR and SFP-25G-LR. The former is designed to transfer data over short distance (up to 100m over MMF) while the latter is suitable for long distance transmission (up to 10 km over SMF). Utilizing 25GbE SFP28 leads to a single-lane connection similar to existing 10GbE technology, however it can deliver 2.5 times more data, which enables network bandwidth to be cost-effectively scaled in support of next-generation server and storage solutions.

Are the SFP, SFP+ and SFP28 Products Backward Compatible?

In most cases the connector and cable assembly are all backward compatible – an SFP+ connector is a direct replacement for an SFP connector to ensure simple upgrade to customer systems. As these are standard products, the cable assembly will also be compatible between the systems – an SFP copper cable assembly can be inserted to an SFP+ cage and mate with a SFP+ connector on the board.

Then how about the new SFP28 product? Since transceivers with various SFP connector types have become an important constituent of data communication network, compatibility issue of SFP28 and SFP+ is controversial among many subscribers. Here is a typical topic from Reddit, and it says like “For a project we’re looking to purchase some nexus 93180YC-EX ToRs for 25Gb+ down to the compute nodes. Cisco states that the downlink 25Gb ports are also 10Gb capable, but one can only really assume that means that the port is compatible with SFP+ optics too. Cisco’s SFP+ compatibility matrix appears to support that claim, however just curious if any of you have any SFP28 experience yet to confirm?”

The answer is definitely “yes”. SFP28 adopts the same form factor as SFP+, just running at 25 Gb/s instead of 10Gb/s, which offers better performance and higher speed. Besides, the pinouts of SFP28 and SFP+ connectors are mating compatible. Therefore, SFP28 connector is backwards compatible with SFP+ ports. That is to say, an SFP28 can be plugged into an SFP+ port and vice versa, but plugging an SFP+ into an SFP28 port would not get you 25Gb/s data rates.

Conclusion

SFP28 vs SFP+ vs SFP connector? Have you made clear which one to choose? Whether choosing SFP or SFP+ depends on your switch types. If your switch port only supports 1G, you can only choose the 1000BASE SFP (eg.MGBSX1). If it is a 10G switch, it depends on the speed and distance you require. When choosing between SFP28 and SFP+, it all depends on the transmission data rates you need. The SFP28 aims to build 25GbE networks that enables equipment designers to significantly reduce the required number of switches and cables. Thus when considering reduced facility costs related to space, power and cooling, the SFP28 would be the optimal choice for you.

What’s the Difference: 10GBASE-SR vs 1000BASE-SX

As the development of fiber optic network, there appears lots of industry standards for fiber optic transceivers. Although transceivers with different standards may have different features and performance, they sometimes can be used in the same switch port. Thus, many people may get confused by these transceivers. For example, 10GBASE-SR and 1000BASE-SX transceivers can both be inserted into the Cisco Catalyst 2960S-48TD-L switch, but the 10GBASE-SR transceiver may not work fine with the 1000BASE-SX module in another switch. Why? This post will discuss 10GBASE-SR vs 1000BASE-SX and whether 10GBASE-SR transceiver can down-support connect to 1000BASE-SX transceiver.

connect 10GBASE-SR to 1000BASE-SX

10GBASE-SR vs 1000BASE-SX

As mentioned above, 10GBASE-SR and 1000BASE-SX are two kinds of industry standards for fiber optic transceivers. This part will introduce them in turns.

10GBASE-SR

10GBASE-SR is defined in the IEEE 802.3 Clause 49 standard, specially designed for multi-mode fiber optic medium that uses 850 nm lasers. It has a data transmission rate of up to 10.3125 Gbps and can be used over multiple cabling options. But the transmission distance may differ as the fiber cable changes. For example, when used over OM1 cabling, the 10GBASE-SR has a maximum working distance of 33 meters, as opposed to 82 meters when applied over OM2 cabling. Nowadays, the 10GBASE-SR module usually applied over OM3 and OM4 cablings to give a more structured optical cabling used in large buildings. And the transmission distance respectively are 300m and 400m.

1000BASE-SX

Like 10GBASE-SR, 1000BASE-SX is also an IEEE 802.3z standard for the multi-mode fiber optic cabling. But it has a minimum transmission distance of 220m and a maximum of 550m. Offering 1Gbps data transmission rate, 1000BASE-SX modules are mainly used to connect high-speed hubs, Ethernet switches, and routers together in different wiring closets or buildings using long cabling runs.

Can 10GBASE-SR Transceiver Down-Support Connect to 1000BASE-SX Transceiver?

10GBASE-SR modules are generally referring to 10GBASE-SR SFP+ transceivers, and 1000BASE-SX modules are usually 1000BASE-SX SFP transceivers. And since SFP+ and SFP transceivers share the same size (as shown below), SFP transceivers can often used in most SFP+ ports (For example, almost all SFP+ ports of Cisco switch can accept SFP transceivers). Then can a 10GBASE-SR SFP+ transceiver down-support connect to the 1000BASE-SX SFP transceiver?

10GBASE-SR vs 1000BASE-SX

10GBASE-SR vs 1000BASE-SX Transceivers

The answer is no. Unlike copper SFP transceivers, 10GBASE-SR SFP+ transceivers do not have such functions as auto-negotiation. In fact, both 10GBASE-SR SFP+ and 1000BASE-SX SFP transceivers can only run at the rated speed fixed by the electro-optical conversion ASIC built into the transceiver hardware. That’s to say, 10GBASE-SR SFP+ transceivers can only run at 10Gbps and 1000BASE-SX SFP transceivers run at 1Gbps. So there is no such fiber link that one end does 1G while the other end does 10G.

10GBASE-SR vs 1000BASE-SX: Have You Known the Differences?

To conclude, although 10GBASE-SR and 1000BASE-SX share something in common, they are totally different Ethernet standards for transceivers. 10GBASE-SR SFP+ transceivers mainly work in 10G links, while 1000BASE-SX transceivers can only run at 1Gbps even though in the SFP+ slot. Thus, it will not work out to connect a 10GBASE-SR SFP+ transceiver with a 1000BASE-SX SFP transceiver.

Related Article: What Is SFP Connector, SFP+ Connector and SFP28 Connector?
Related Article: Choose 10GBASE-T Copper Over SFP+ for 10G Ethernet

Compatible SFP Modules for Mikrotik CRS125-24G-1S-IN & CRS125-24G-1S-RM

Mikrotik CRS125-24G-1S series cloud router switch is available in Mikrotik CRS125-24G-1S-IN and Mikrotik CRS125-24G-1S-RM two models. It combines the best features of a fully functional router and a Layer 3 switch, is powered by the familiar RouterOS. As we know, these two models switch both have one SFP port. Then, what SFP modules can you choose for your switch? This blog will give some choices.

Overview for CRS125-24G-1S-IN and CRS125-24G-1S-RM Switch
As show in the figure below, both Mikrotik CRS125-24G-1S-IN and Mikrotik CRS125-24G-1S-RM switches have 24 RJ45 ports and 1 SFP port. One is a desktop type, and the other is a 1U rackmount type. You can according to your specific needs to choose the right one.

CRS125-24G-1S-IN CRS125-24G-1S-RM

Detailed specifications for CRS125-24G-1S and CRS125-24G-1S-RM are listed in the following table:

CPU Qualcomm Atheros AR9344 600 MHz
Memory 128MB
Ethernet 24x 10/100/1000 Mbit/s Gigabit Ethernet with Auto-MDI/X
Expansion microUSB port
Storage 128MB Onboard NAND with multiple OS partition support
Serial port One RJ45 serial port
Extras Reset switch; beeper; voltage and temperature monitoring, touchscreen LCD
Power options 8-28V, 24V 0.8A PSU included
Case dimensions 285x145x45mm
Temperature -35C to +65C tested
OS MikroTik RouterOS v6, Level 5 license
Included CRS switch, power adapter, and USB OTG cable (for 4G dongle or USB drive)

User Guide for CRS125-24G-1S-IN and CRS125-24G-1S-RM Switch
The CRS125-24G-1S and CRS125-24G-1S-RM are preinstalled with RouterOS and are ready to use. Switch is compatible with RouterOS v6 and newer, if your switch comes preinstalled with an earlier version, please upgrade before using it. For CRS125-24G-1S and CRS125-24G-1S-RM: All the ports are switched. Both models can be accessed though the IP 192.168.88.1, username is admin and there is no password. Please connect with your web browser to this IP address to configure it.

Compatible SFP Modules for CRS125-24G-1S-IN & CRS125-24G-1S-RM Switch
According to Mikrotik cloud router switch guide, CRS125-24G-1S-IN and CRS125-24G-1S-RM switches are compatible with 1.25G SFP modules. SFP+ port supports only modules up to 10KM LR (long reach). FS.COM provides a full range of compatible 1.25G SFP modules at high quality and low price, which can work well in Mikrotik switches. 1000BASE-SX SFP modules are only sold at US$  6.00. Part of the products from FS that are compatible with this Mikrotik CRS125-24G-1S-IN and CRS125-24G-1S-RM switches are listed below for your reference.

FS P/N Description
SFP-GB-GE-T Generic Compatible 1000BASE-T SFP Copper RJ-45 100m Transceiver
SFP-GB-GE-T Generic Compatible 10/100/1000BASE-T SFP Copper RJ-45 100m Transceiver
SFP1G-SX-85 Generic Compatible 1000BASE-SX SFP 850nm 550m DOM Transceiver
SFP1G-SX-31 Generic Compatible 1000BASE-SX SFP 1310nm 2km DOM Transceiver
SFP-LX Generic Compatible 1000BASE-LX/LH SFP 1310nm 10km DOM Transceiver

Related Article: Mikrotik CRS317-1G-16S+RM Transceiver/DAC Cable Solution

40G Transceiver vs 100G Transceiver: Which One Is Worth the Investment?

Today, the trend for high-speed data transmission and high-bandwidth is overwhelming. Some years ago, people had witnessed upgrading from 10Mbps Ethernet to 100Mbps Ethernet. And the migration from 1G to 10G was happened not very long ago. But now, whether you believe it or not, prepared or not prepared, 40G and 100G have already on the way. Meanwhile, 40G transceiver and 100G transceiver are widely deployed among data center managers and IT engineers. 40G transceiver vs 100G transceiver, which one is worth the investment.

The Rise of 100G

To begin with, it has to be made clear that the market trend is 100G Ethernet, which will eventually become the mainstream in the future. The strong demand in 100G Ethernet is being driven by cloud services and hyper-scale data centers. And there is a demand for lower-priced 100G pluggable transceivers from data center customers. Currently, the market transition to 100GE is in full swing, fueled primarily by the seemingly insatiable need for networking bandwidth by hyper-scale data centers and cloud services. As it has been shown in the picture below, 100G Ethernet transceivers will exceed 15 million units a year.

100G market

This tremendous growth in deployments by a small number of key customers, together with a large number of suppliers competing for these orders, will undoubtedly drive down the cost of 100GE modules rapidly. It is predicted that the cost of 100G optical transceiver is expected to decline by 75% in the next couple of years. In the meantime, Facebook has publicly set a target cost of $100 for a 100G transceiver with a reach of less than 2km. While the Facebook target appears to be years away, we believe that a 70% cost reduction in 2 years is possible. By that time, the 100G transceiver will be more affordable.

Why not 40G?

If you ask me why 40G Ethernet will be obsolete? The short answer is “cost”. From the technical point, The primary issue lies in the fact that 40G Ethernet uses 4x10G signalling lanes. On UTP, 40G uses 4 pairs at 10G each. Early versions of the 40G standard used 4 pairs, but rapid advances in manufacturing developed a 4x10G WDM on a single fiber optic pair. Each 40G SFP module contains a silicon chip that performs multiplexing so that the switch see 40 gigabits in and 40 gigabits out. It’s similar to Coarse Wave Division Multiplexing when using fiber. When you buy a 40G cable or QSFP, you are paying for the cost of the chip and software, plus the lasers, etc. When using 25/50/100G, the “lane speed” is increased to 25 gigabits per second. For 100G Ethernet, there are four 25G signalling lanes. It’s cheaper to buy 100G with four lanes rather than 40G with a four-lane MUX.

40GEthernet

Scale up to 100G with FS 100G Optics Solution

As one of the leading providers in optical communication , FS provides customers with 100G optics that are manufactured at the highest quality of standards in the industry, including QSFP28, CFP, CFP2, CFP4, 100G patch panels, 100G switches, etc. Part of the products are listed as follow:

Model ID Description    Price

48862

Juniper JNP-QSFP-100G-SR4 Compatible 100GBASE-SR4 850nm 100m Transceiver

   US$  269

48354

Cisco Compatible QSFP28 100GBASE-SR4 850nm 100m Transceiver

   US$  269

65228

Juniper Networks CFP-100GBASE-SR10 Compatible 100GBASE-SR10 850nm 150m Transceiver

   US$  1,500

Summary
100G Ethernet are racing to market and will finally takeover the 40G market. FS provides both 40G transceiver and 100G transceiver for your network deployment. They are compatible with major brands, like Cisco, Brocade, Juniper, Dell, Arista, etc. If you had any inquiry, you can kindly visit www.fs.com.

Related Article: Preparation for 40G/100G Migration

100G Coherent CFP Module for Metro Network Applications

Due to the rapid increase of communication traffic, the requirement for core networks to handle larger capacity and longer distance on their links has led to a spread of 100G optical networks. For this environment, service providers are adopting coherent transceivers for their 100G DWDM backbone applications. Until recently, coherent CFP/CFP2 DWDM optical transceivers had been the technology of choice for transporting 100G traffic over long distances or as part of a DWDM network. This paper will mainly discuss 100G coherent CFP module for metro network application.

Coherent Technology: Making 100Gb/s Available

Moving from 10Gb/s to 100Gb/s line speeds comes with technical challenges. Coherent technology had been investigated for optical transmission since the 1980s as a means to increase transmission distances. By 2010 to 2011, the technology had reached a point of market maturity. At this time, it could genuinely allow 100G coherent signals. This result forms the foundation of the industry’s drive to achieve transport speeds of 100G and beyond, which helps to deliver Terabits of information across a single fiber pair at a lower cost. Until now, coherent technology has been mainly deployed in long-haul networks, and it is now starting to be deployed in metro networks.

Capacity Enabled by Coherent Technology

Figure 1: Capacity Enabled by Coherent Technology

Metro Requirements for 100G

100G rates were initially deployed in the long-haul and core networks. In the Metro, 10G is still the most dominant rate. In the coming years, the trend toward aggregation into 100G in the larger metro areas or data center connectivity will become more significant. The metro covers a broad range of distances: the metro regional and metro core cover distances of 500-1000 km and 100-500 km respectively, while the metro access links are generally point-to-point connections shorter than 100 km. Although these distances are shorter than long-haul links, the characteristics of metro network- including flexible protocol support, higher granularity of signal rates and increased number of nodes- create the requirements for 100G rates.

Three Types of Metro Network

Figure 2: Three Types of Metro Network

100G Coherent CFP Module for Metro Network Applications

While metro and long haul applications have different requirements, the lower-cost 100G technology for the metro is demanded for service providers. To achieve this feat, equipment vendors consider coherent CFP modules as the ultimate solutions for metro 100G deployments. Coherent 100G CFP can overcome optical transmission impairments and still achieve acceptable performance.

Scenario 1: 100G Multi-Channel DWDM Networking

An Architecture of Coherent CFP modules for 100G Deployment

Figure 3: An Architecture of Coherent CFP Modules for 100G Deployment

As shown in Figure 3, since the 100G rates are more susceptible to dispersion, they would require extra dispersion compensation and optical power boost. Thus an extra 100GHz DWDM multiplexer is first used to combine all the 100G rates together followed by a combined dispersion compensation and amplification stage. This architecture conveniently supports the ‘pay-as-you-grow’ model for service providers. When the bandwidth is exhausted, the existing legacy 10G channels may be seamlessly interchanged with 100G services. The same remaining components can even be reused to extend the data rate up to 2.4 Tb/s.

This scenario would require 24 differently colored CFP modules deployed together with the already existing 48 channel 100 GHz DWDM multiplexer. All the 100G services are first multiplexed together such that only one dispersion compensation and amplification stage suffices. Clearly, such a network architecture provides higher density with capability to reuse existing infrastructure with flexibility while remaining cost friendly.

Scenario 2: 100G Distance Extension Solutions

100G Coherent DWDM Transport by Using SFP+ OEO Transponder

Figure 4: 100G Coherent DWDM Transport by Using SFP+ OEO Transponder

In this scenario, the switch was tested with SFP+ OEO transponders for simple distance extension solutions. The 100G output signals from the switch are converted to DWDM signals that can be transmitted over longer distance. The solution removes the distance limitations by using a coherent CFP module to connect the output signal to the line fiber and carry the signal over longer distances.

As shown in Figure 4, to achieve higher cabling density with Cisco CFP 100G optics, the architecture mixed a 16 channels dual fiber DWDM Mux Demux which can be used for CWDM/DWDM hybrid and 8 channels dual fiber CWDM Mux Demux, by adding MTP harness cable and WDM SFP+ OEO converter to transfer the regular SR wavelength to DWDM wavelengths. Therefore, building a long distance 2500km DWDM networks in 100G coherent CFP modules and cost effective way will be achieved.

Conclusion

100G coherent CFP modules provide cost-effective electronic equalization of fiber impairments and extensive performance monitoring capabilities that enable easy installation and network management. These benefits help service providers meet bandwidth demand growth while reducing the total cost of ownership.

Related Article: CFP Transceiver Module Overview: CFP, CFP2, CFP4 & CFP8