Tag Archives: QSFP28

25GbE–A New Trend For Future Ethernet Network

Nowadays, the requirement for bandwidth in cloud data centers is increasing strikingly. To meet the demand for higher bandwidth, networking and the Ethernet industry are moving toward a new direction. Discussions previously focusing on 10GbE and 40GbE are now shifting onto 25GbE. It seems that 25GbE is more preferred and accepted by end users, which poses a threat to 10GbE and 40GbE. Why does it happen? This post will lead you to interpret 25GbE in an all-sided perspective.

25GbE–A New Trend for Future Ethernet Network

25GbE—An Emerging Standard

25GbE is a standard developed by IEEE 802.3 Task Force P802.3by in July 2014, used for Ethernet servers and switches connectivity in a data center environment. The single lane design of 25GbE gives it a low cost per bit, which enables cloud providers and large-scale data center operators to deploy fewer switches and cables to meet the needs while still scaling their network infrastructure. The following table provides a summary of key upcoming IEEE standard interfaces that specify 25GbE.

25GbE–A New Trend for Future Ethernet Network

Figure 1: IEEE 802.3 standard Interfaces that specify 25GbE

Cloud Will Drive to QSFP28 and SFP28

The 25GbE physical interface specification supports two main form factors—SFP28 and QSFP28.
SFP28 is used for a single 25GbE port. The SFP28-25G-SR-S is an 850nm VCSEL 25GbE transceiver which is designed to transmit and receive optical data over 50/125µm multimode fiber (MMF) and support up to 70m on OM3 MMF and 100m on OM4 MMF.

The QSFP28 transceiver and interconnect cable is a high-density, high-speed product solution designed for applications in the telecommunication. The interconnect offers four channels of high-speed signals with data rates ranging from 25 Gbps up to potentially 40 Gbps, and will meet 100 Gbps Ethernet (4×25 Gbps) and 100 Gbps 4X InfiniBand EDR requirements.

100GBASE-SR4-with-four-25GBASE-SR-SFP28

Figure 2: FS.COM optical transceivers for 25GbE solution

Why Choose 25GbE

While 10GbE is fine for many existing deployments, it cannot efficiently deliver the bandwidth required by next-generation cloud and web-scale environments. And 40GbE isn’t cost-effective or power-efficient in ToR switching for cloud providers. Thus, 25GbE was designed to break through the dilemma.

Number of SerDes Lanes

SerDes is an integrated circuit or transceiver used in high-speed communications for converting serial data to parallel interfaces and vice versa. The transmitter section is a serial-to-parallel converter, and the receiver section is opposite. Currently, the rate of SerDes is 25 Gbps. That is to say, we can only use one SerDes lane at the speed of 25 Gbps to connect from 25GbE card to the other end of 25GbE card. In contrast, 40GbE needs four 10GbE SerDes lanes to achieve connection. As a result, the communication between two 40GbE cards requires as many as four pairs of fiber. Furthermore, 25 Gbps Ethernet provides an easy upgrade path to 50GbE and 100GbE networks, which utilize multiple 25GbE lanes.

Numbers of lanes needed in different Gigabit Ethernet

Figure 3: Numbers of lanes needed in different Gigabit Ethernet

Utilization of PCIe Lanes

At present, the mainstream Intel Xeon CPU only provides 40 lanes of PCIe 3.0. The lane bandwidth of a single PCIe 3.0 is about 8 Gbps. These PCle lanes are used for many connections. Therefore, it is necessary to consider the utilization of limited PCIe lanes by the network cards. Single 40GbE NIC needs at least one PCIe 3.0 x8 slot, so two 40GbE cards need to occupy two PCIe 3.0 x8 lanes. Even if the two 40GbE ports can run full of data at the same time, the actual lane bandwidth utilization is only: (40G+40G) / 8G*16= 62.5%. On the contrary, 25GbE card only needs one PCIe 3.0 x8 lane, and then the utilization efficiency is 25G*2 / (8G*8) = 78%. Apparently, 25GbE is significantly more efficient and more flexible than 40GbE in terms of the use of PCIe lanes.

10GbE vs 25GbE vs 40GbE

25GbE enables resellers and their customers to provide 2.5X the performance of 10GbE, making it a cost-effective upgrade to the 10GbE infrastructure. Since 25GbE is delivered across a single lane, it provides greater switch port density and network scalability compared to 40GbE, which is actually four 10GbE lanes. Thus, it costs less, requires lower power consumption and provides higher bandwidth. What’s more, 25GbE can run over existing fiber optic cable plant designed for 10, 50 or 100GbE and also 40GbE by changing the transceivers.

Bandwidth comparison for 25GbE and other Ethernet speeds

Figure 4: Bandwidth comparison for 25GbE and other Ethernet speeds

Summary

No matter the market research or the attitude of users, 25GbE seems to be the preferred option down the road. Actually, coming back to reality, there will be a significant increase in 100GbE and 25GbE port density in the next few years. If you need any optics and cabling solution for your 25GbE infrastructure, feel free to contact sales@fs.com.

Difference Between QSFP, QSFP+, QSFP28

SFP is short for small form factor. It refers to fiber optic transceivers supporting 1Gbps data rate. Except SFP, current market is full of various types of fiber optic transceivers, such as QSFP, QSFP+ and QSFP28. At the first sight, these transceiver modules are very similar. But actually, they have big differences. To know the difference clearly is good to make the right choice for your network connection. So what are the differences between QSFP,  QSFP+, QSFP28?

QSFP vs QSFP+

“Q” of QSFP means quad (4 channels). QSFP is a compact, hot-pluggable transceiver used for data communications. The QSFP specification supports Ethernet, Fibre Channel, InfiniBand and SONET/SDH standards with different data rate options. QSFP transceivers support the network link over singlemode or multimode fiber patch cable. QSFP modules are commonly available in several different types: 4x1G QSFP, 4x10G QSFP+, 4x28G QSFP28. From this side, QSFP vs QSFP+ vs QSFP28 all share the same small form-factor. literally QSFP uses 4x1G lanes and was only found in some FC/IB contexts.

While QSFP+ transceivers, evolving from 4x1G lanes (QSFP) to 4x10G lanes, are designed to support 40G Ethernet, Serial Attached SCSI, QDR (40G) and FDR (56G) Infiniband, and other communications standards. QSFP+ standard is the SFF-8436 document which specifies a transceiver mechanical form factor with latching mechanism, host-board electrical-edge connector and cage. QSFP+ modules integrates 4 transmit and 4 receive channels plus sideband signals. Then QSFP+ modules can break out into 4x10G lanes. QSFP+ modules are used to connect switches, routers, Host Bus Adapters (HBAs), enterprise data centers, high-performance computing (HPC) and storage. But some may think QSFP as the same with QSFP+, especially in the Ethernet world.

QSFP+ vs QSFP28

QSFP+ and QSFP28 differs in “28” as the name says. QSFP28 is a hot-pluggable transceiver module designed for 100G data rate. QSFP28 integrates 4 transmit and 4 receiver channels. “28” means each lane carries up to 28G data rate. QSFP28 can do 4x25G breakout connection, 2x50G breakout, or 1x100G depending on the transceiver used. While QSFP+ supports the data rate of 40G, 4 channels for transmitting and 4 channels for receiving, each lane carrying 10G. QSFP+ can break out into 4x10G or 1x40G connection.

qsfp28 vs qsfp+

Usually QSFP28 modules can’t break out into 10G links. But it’s another case to insert a QSFP28 module into a QSFP+ port if switches support. At this situation, a QSFP28 can break out into 4x10G like a QSFP+ transceiver module. One thing to note is that you can’t put a QSFP+ transceiver into a QSFP28 port to avoid destroying your optics.

FS.COM QSFP+ vs QSFP28

Compatible with major brands such as Cisco, Juniper, Arista, Brocade, etc., FS.COM QSFP+ and QSFP28 modules can support both short and long-haul transmission. Here lists our generic QSFP+ and QSFP28 modules in the following table.

FS.COM Generic QSFP+
Model Description Price List In Stock
17931 40GBASE-SR4 QSFP+ 850nm 150m MPO Transceiver for MMF US$ 49.00 1061 pcs
34917 40GBASE-PLRL4 QSFP+ 1310nm 2km MPO Transceiver for SMF US$ 220.00 49 pcs
24422 40GBASE-LR4 and OTU3 QSFP+ 1310nm 10km LC Transceiver for SMF US$  340.00 50 pcs
34912 40GBASE-CSR4 QSFP+ 850nm 400m MPO Transceiver for MMF US$  70.00 141 pcs
35205 40GBASE-UNIV QSFP+ 1310nm 2km LC Transceiver for SMF&MMF US$  340.00 18 pcs
34913 40GBASE-LR4L QSFP+ 1310nm 2km LC Transceiver for SMF US$ 340.00 44 pcs
48721 40GBASE-SR Bi-Directional QSFP Module for Duplex MMF US$  300.00 106 pcs
35209 40GBASE-PLR4 QSFP+ 1310nm 10km MPO Transceiver for SMF US$  380.00 34 pcs
35211 40GBASE-ER4 and OTU3 QSFP+ 1310nm 40km LC Transceiver for SMF US$  1,500.00 40 pcs
39986 40GBASE-LR4 CFP 1310nm 10km SC Transceiver for SMF US$  800.00 Available
FS.COM Generic QSFP28
Model Description Price List In Stock
35182 Generic Compatible QSFP28 100GBASE-SR4 850nm 100m Transceiver US$ 270.00 38 pcs in stock
65216 Generic Compatible QSFP28 100GBASE-PSM4 1310nm 500m Transceiver US$ 750.00 26 pcs in stock
65214 Generic Compatible QSFP28 100GBASE-CWDM4 Lite 1310nm 2km Transceiver US$ 1,350.00 26 pcs in stock
65215 Generic Compatible QSFP28 100GBASE-CWDM4 1310nm 2km Transceiver US$ 1,350.00 26 pcs in stock
39025 Generic Compatible QSFP28 100GBASE-LR4 1310nm 10km Transceiver US$ 2,800.00 Available
Conclusion

The difference between QSFP vs QSFP+ vs QSFP28 has been stated clearly in this article. Though QSFP is thought as QSFP+, when talking about 40G, actually we mean QSFP+. QSFP+ vs QSFP28 mainly differs in data rate and breakout connection. So you must be sure what you need is 40G QSFP+ or 100G QSFP28 for high density applications, especially when connecting with 10G SFP+.

Related Article:  How to Match Fiber Patch Cable for Your Multimode SFP?

The Newly Released 25GbE Ethernet Standard

As the increasing bandwidth requirements of private and public cloud data centers and communication service providers, 25Gbps Ethernet over a single lane will have a significant impact on server interconnect interfaces. It may become the new upgrade path to 100G (10G-25G-100G instead of 10G-40G-100G). This article will give brief introduction about 25GbE Ethernet.

What’s 25GbE Ethernet

25GbE Ethernet standard is proposed for connectivity in the data centers. Because of the increasing demand for higher speed network performance and maintaining Ethernet economics, IEEE agreed to support the development of 25GbE standard in June 2014. 25G Ethernet is defined for 100GbE implemented as four 25Gbps lanes running on four fiber or copper pairs. 100G Quad small for-factor pluggable transceiver (QSFP28) have four lasers, each transmitting 25Gbps. The twisted pair pair standard was derived from 40GbE standards development. The following table shows the main upcoming interfaces for 25Gbps.

25G-strandard-interface

Number of Lanes 40G QSFP+ interface is constructed from four parallel links. Extending QSFP+ onto fiber requires four parallel 10Gb streams to transport this to the receiving QSFP+ parallel optics. The data transmission is achieved by four lanes which significantly reduce switch port density per switching chip and increases the cost of cabling and optics. While the 25GbE standard requires only a single lane, while delivering 2.5 times more throughput compared to current 10GbE solutions and significantly saving the cost compared to 40GbE solutions.

Form Factors The 25GbE physical interface specifications support the form factors including QSFP28 and SFP28. QSFP28 has four lanes and each lanes supports 25 Gbps speed. SFP28 has only one lane and it also supports 25 Gbps speed. Current switch doesn’t support 25G SFP28 port. So the solution for 25G is to use a breakout cable that allows four 25GbE ports to connect to a 100GbE QFSFP28 switch port.

Benefits of 25GbE Ethernet

First, more data and switch port density. Compared with 10G solution, 25GbE standard can provide 2.5 times more data. And it can also offer 4 times switch port density compared to 40G solution. Second, save the cost. Since it can provide greater port density, fewer ToR switches and cables are needed. In that way, it reduces the construction cost compared with 40GbE. Third, it features lower power and smaller footprint requirements. Due to these special benefits, 25GbE is believed to be popular in no time. According to a recent five-year forecast, it’s said that annual shipments of 25GbE ports will be 2.5 times greater than 40GbE ports by 2018.

25G-forecast

25G Solutions

Fiberstore (FS.COM) has released 25G DAC (direct attach copper) cables which include 100G QSFP28 to 4xSFP28 and 25G SFP28 to SFP28 with the length from 1 m to 5 m. QSFP28 refers to the 100G DAC cable using the QSFP+ form factor, and SFP28 refers to the 25G DAC cable using the SFP+ form factor. The form factor remains the same but the new standard will require improved cables and connectors capable of handling additional bandwidth. Existing QSFP+ and SFP+ cable assemblies are not compatible with QSFP28 and SFP28 ports. 25G DAC is designed as the low-cost copper connection for ToR switches.

25G-dac cable

It’s certain that Fiberstore will soon release 25GBASE-T interface equipment. 25GBASE-T can support 30 meters long reach with low cost. It’s a cost-effective solution for ToR server connections using point-to-point patch cords, and enable End of Row (EoR) or Middle of Row (MoR) by using the 30 meter structured cabling. The connection can be achieved with the common use of RJ45 plug and connector. Compared with 25G DAC, it seems to be a more suitable way.

Conclusion

25GbE can provide up to 2.5 times faster performance than existing 10GbE connections while maximizing the Ethernet controller bandwidth/ pin and switch fabric capability. It can also provide greater port density with lower cost compared to 40GbE solutions. It’s analyzed that 25G will limit the deployment of 40G QSFP+ ports. By now, FS.COM has released 100G QSFP28 to 4xSFP28 and 25G SFP28 to 25G SFP28 DAC cables for 25G network. In the near future, there will more equipment for 25G including 25GBASE-T transceiver. Let’s look forward to it.