SFP (small form-factor pluggable or mini GBIC) is a compact and hot-swappable transceiver optic. It is for plugging into networking equipment and being connected to network cables. With the diversification of applications, the SFP transceiver modules are also varied. So, how to choose an SFP module that is most suitable for your needs? It may be handy for professional network engineers. However, if you are an enterprise procurement staff, picking out and purchasing SFP transceivers may make you feel at a loss. This post lists the paramount factors when choosing SFP optics.
10 Factors to Choose SFP Transceivers
What is SFP module used for? Confirm the application scenarios with your organization, then double-check the following factors before making decisions.
Different network technology requires unique SFP transceivers. Based on networking standards, SFP types are Ethernet SFP, FC SFP, SDH SFP/SONET SFP, SDI SFP, and PON SFP.
FC (Fiber Channel) SFPs are for Storage Area Network (SAN). Common types are 1G FC SFP, 2G FC SFP, 4G FC SFP, 8G FC SFP, 10G FC SFP and 16G FC SFP.
SONET (Synchronous Optical Network) or SDH (Synchronous Digital Hierarchy) SFPs are applied commonly in optical fibers, microwave, and satellite transmission systems. SONET/SDH SFPs cover short-reach OC-3/STM-1 to OC-48/STM-16 SR transceivers, intermediate reach IR1 transceivers, and long reach LR1/LR2 transceivers.
SDI (Serial Digital Interface) SFPs are used to monitor SDI video pathological signals of SDI equipment. The video SFP transceiver includes SD-SDI, HD-SDI, 3G-SDI, 6G-SDI, and 12G-SD.
PON (Passive Optical Network) SFPs are for FTTH application. Pick APON SFP vs BPON SFP vs EPON SFP vs GPON SFP for different PON standards. Then choose OLT SFP vs ONU SFP according to the networking components to be inserted.
Ethernet deployment has taken a large portion of the market share of the networking technology, thence the following introduction will focus on Ethernet SFP modules.
Your SFP transceiver with fiber or copper wires is for connecting two networking devices such as Ethernet switches. Hence figuring out the device port data rate is the key to SFP transceiver data rate selection. The typical port speed of Ethernet switches is 155Mbps, 1Gbps, 10Gbps, 25Gbps, 40Gbps, 100Gbps, and 400Gbps.
As a simple example, a pair of Cisco SG350XG-24F switches are placed in a server room, needing connection for data communication. Then you need 10G SFP+ modules because the two switches own 24 10G SFP+ ports.
The small form-factor pluggable transceivers have derivated into multiple form factors. Hot SFP types are 1G SFP, 10G SFP+, 25G SFP28, 40G QSFP+, 100G QSFP28. SFP transceivers with different form factors support corresponding speed. Check the equipment port types, choose a matching form factor.
Estimate how far between the two ends. If the transmission medium is optical fibers, choose multimode SFP transceivers for short-reach applications and single-mode SFPs for long-distance transmission. For the former, MMF SFPs are frequently used within a kilometer, such as 30m, 100m, 300m, 400m, 550m. 2km is also available in the market. For the latter, a regular SMF SFP can reach up to 10km. Besides, you can choose from 20km, 40km, 80km, 100km, 120km for ultra long haul networks.
For instance, QSFPTEK offers multimode 100GBASE-SR4 QSFP28 that can reach over OM4 fibers and single-mode 100G QSFP28 with a selection of 2km-IR4, 10km-LR4/4WDM-10/PSM4, 40km-ER4, and 80km-ZR4. If the transmission medium is copper cable, do not expect long-distance transmission. The maximum transmission distance of electrical port modules on the market can generally reach 100m.
LC, SC, and MTP/MPO are three fiber SFP transceiver connector types.
LC and MTP/MPO connectors are available for 40G QSFP+ and 100G QSFP28. LC and SC connectors are found on 1G SFPs.
Therefore, check your current situation and consider the following questions:
1. For businesses that need to reutilize existing cabling, what is the type of your fiber optic cable connector? Choose a corresponding SFP connector type to match with the fiber cables.
2. For companies that plan to build up a new system or upgrade their wiring infrastructure, besides SFP transceivers, you also need to buy matching fiber patch cables. Think about how to buy for improving the whole lifespan cost-effectiveness.
Taking 10km 100G QSFP28 as an example, the table below shows the cost of buying a transceiver and matching fibers.
As you can see, though QSFP28 modules with MTP/MPO are cheaper, however, deploying fibers in large quantities later will cost you a lot of money. Pay attention to making a future-proof solution.
Three levels of SFP transceivers are: commercial temperature range (COM: 0~70°C), extended temperature range (EXT: -20°C~85°C), and industrial temperature range (IND: -40°C~85°C). In general, transceiver vendors will supply commercial SFPs and industrial SFPs for the same model. IND modules have a higher level of extreme temperature resistance.
SFP compatibility is due to the inserting equipment brand and models. Be mind buying an SFP that is fully compatible with equipment. Check the SFP compatibility matrix on the brand's official site or consult your vendors to ensure device compatibility.
QSFPTEK provides multiple brands compatible transceiver modules, some of the main-stream brands are:
Each module is 100% tested on brand switches to ensure full compatibility
Make decisions from OEM or third-party vendors. If choosing third-party vendors, pick a reliable one.
OEM optics have the best guarantee of compatibility and quality. However, For most businesses, its disadvantages far outweigh its advantages. Prohibitive price and incompatibility across brands are the two most annoying points.
Third-party SFP transceivers are affordable and MSA compliant (allowing mix-use devices from multiple vendors). What confuses you is — too many choices that it is difficult to distinguish whether they are reliable or not. However, as long as you make a good choice, you save a lot and have no worry about its compatibility and quality. As the decoding technology on the market is quite mature.
The SFP DOM (digital diagnostics monitoring) is a function to allow monitoring real-time operating parameters. Pick DDM SFP to stay informed about module working performance and help quickly locate the link fault.
Price & Budget
In addition to studying SFP transceiver price comparison from different manufacturers, think one more question — are there more cost-effective alternatives? For example, an end-to-end connection is required between two switches on the rack, and the distance is very short. Then maybe you can consider using a high-speed cable that does not need extra fiber patch cables.
Sometimes you may also need to consider other parameters of the module, such as whether the transmission mode is simplex or duplex; whether the service policy warranty covers the five-year life cycle of the module.
Figure out what your networking technology is and which equipment and cables are in your system, go further to transmission speed for a matching form factor, and transmission distance to pick a single-mode or multimode SFP with the required reach. Take cabling infrastructure into consideration for a proper SFP connector type. Give priority to industrial SFPs if you need to use the module in harsh environments for extreme temperatures. Choose a reliable vendor that ensures device compatibility. Do not forget the SFP DOM funcation.
Follow the top 10 factors for choosing an SFP transceiver module, your options will slowly narrow down. Now that you are almost there. Finally double-check your SFP transceiver use scenarios.