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10G Stacking Over Cat6a or DAC

10G Stacking Over Cat6a or DAC

We have got benefits from the stacking of 10G SFP+ switches for the past decades, and the 10G SFP+ direct attach cable (DAC) makes the stacking low-cost. But when 10GBASE-T becomes a new port choice on 10G switches, stacking on 10G switches has to meet the issue about whether to choose Cat6a or SFP+ DAC. At first people think that Ethernet cable is cheaper and easier to deploy than SFP+ DAC, but later they realized the issue is not only about the cable cost.

  10G stacking-cat6a or DAC

Comparison of Stacking 10G Over Cat6a and SFP+ DAC

Before going on, it should be noted that this discussion is focused on 10G stackable switches that have both 10GBASE-T ports and SFP+ ports (such as Cisco 550X series switches, Dell 8024).

In terms of the cost, one Cat6a cable costs just one third of a 10G SFP+ DAC of the same length. But cable price is not the only factor that contributes to the total budget in building a network. Let’s see some properties of these two technologies.

Power Consumption
SFP+ DAC Cat6a
Power Consumption Per Port 1-1.5 W 4-6 W
Max. Reach 10 m 100 m

Obviously, SFP+ DAC uses much less power than Cat6a cable. It is important to know that for every watt of power consumed, typically two additional watts are needed for cooling. If there is a lot of ports in the stacking, this power consumption will be significant. So when power consumption matters a lot in your stacking, it will be a huge saving to choose SFP+ DAC instead of Cat6a.

10G cable power consumption
More ports mean more power consumption.
Latency

Also in a case when low latency is strictly required, like in automated financial trading, it is also better to use SFP+ DAC for 10G stacking. Because for the same links and lengths, Cat6a presents higher latency than SFP+ DAC.

automated financial trading low latency
Automated financial trading requires low latency.
Distance

When you have many stacked 10G switches located at different places, i.e. at separate floors or at opposite ends of a hallway, Cat6a can achieve the stacking connection if it is less than 100 m. But typically you’ll be suggested to use fiber link, because the power consumption in long-term could exceed the extra cost for buying 10G fiber optics and cables.

10G stacking distance
The stacking distances affect the cable choice.

As for distances more than 100 m, neither SFP+ DAC nor Cat6a can work. You have to turn to fiber optic patch cable and 10G SFP+ transceiver module.

Conclusion

Considering the total cost and performance of Cat6a and SFP+ DAC for 10G stacking, SFP+ DAC appears to be a better choice in short range. The low power consumption and low latency properties can help accomplish a good stacking, and thus shortening the downtime, improving resiliency, and simplifying administration.

10G SFP+ Copper Transceiver Solution

10G SFP+ Copper Transceiver Solution

It’s said that switch manufacturers are entering into the new fiber transceiver era. Only SFP+ or SFP cages are implemented for future flexibility. And copper ports were only implemented for management purpose so far. However, we cannot deny the fact that there are some applications in the past with 1G where Servers or other components do only have 1G copper ports. So 1G copper SFPs have the right to exist. Now all connections moved from 1G to 10G and the copper ports disappeared so far. But a while ago some vendors started implementing 10G SFP+ copper transceivers to their devices again. One of the main applications in data centers is using SFP+ DAC cables. But the use of RJ-45 cables is often easier than using a copper DAC.

Basic Information on 10G SFP+ Copper Transceiver

The 10G SFP+ copper transceiver is specifically designed for high speed communication links that require 10 gigabit ethernet over Cat 6a/7 cable. This is the first SFP+ transceiver that offers 10Gb/s communication over this type of media. 10G SFP+ copper transceiver uses 10GBASE-T technology, which enables 10 Gigabit Ethernet to operate over balanced twisted-pair copper cable, including Cat6a unshielded and shielded cabling. Compare with 10G optical transmission, 10G SFP+ copper transceiver uses copper cables, which offers great savings and flexibility during network deployment.

Just as all other BASE-T implementations, 10G SFP+ copper transceiver supports lengths up to 100 meters, which gives IT managers a far greater level of flexibility in connecting devices in the data center and accommodating top of rack, middle of row, or end of row network topologies. Moreover, it also gives IT managers the most flexibility in server placement, since it works with existing structured cabling systems.

Reasons to Buy/Advantages of 10G SFP+ Copper Transceiver

With more and more 10GBASE-T network equipment available on the market , data center decision makers will consider to take advantage of the cost savings, convenience, and flexibility provided by deploying 10G technology over balanced twisted-pair copper cabling.

There exist several compelling reasons to buy a 10G SFP+ copper transceiver, both from a network equipment designer and data center manager prospective. And the advantage of 10G copper transceiver can be summarized as follow:

  • Reach: Up to 30m over CAT6a UTP cable, sufficient for all network access use cases
  • Cost: Pay-as-you-grow model that performs for today and scales for tomorrow
  • Reliability: The RJ-45 connector interface is rock solid. No surprises when deployed in your data center.
  • Innovation: Hot–pluggable with a managed soft-start
  • Performance: Full PHY (physical level) presentation, which means nothing is missing
  • Smaller Footprint: Interoperable with any SFP+ cage and connector system
Application Scenarios For 10G SFP+ Copper Transceiver

As it has been mentioned before, 10G SFP+ copper transceiver is based on 10GBASE-T, which has the advantage of being an interoperable, standard-based technology that uses the familiar RJ-45 connector and provides backwards compatibility with legacy networks. Supporting top of rack, middle of row or end of row architectures, 10G SFP+ copper transceiver can extend the life of any switch hardware, without having to change the existing infrastructure. The following pictures present the two application cases for 10G SFP+ copper transceiver.

Case one: Connecting server and/or storage appliances with 10GBASE-T RJ-45 to a SFP+ network switch

10GBASE-T-Copper-applications-and-use-cases

Case two: Network upgrade to 10G at edge switches

network-upgrade-to-10G

FS 10G SFP+ Copper Transceiver Solution

FS 10G SFP+ copper transceivers are high performance, cost effective modules supporting a data rate up to 10Gbps with 30 Meter link length over Cat6A /Cat7. It is designed for application where optical connections not possible or direct attached cable (DAC) Connection are too short. Moreover, FS 10G SFP+ copper transceivers are compliant with brands like Cisco and Arista. And every transceiver from FS is individually tested on corresponding equipment such as Cisco, Arista, Juniper, Dell, Brocade and other brands, passed the monitoring of FS intelligent quality control system. For further information on our products, please contact us at www.fs.com.

25G SFP28: What Makes It Different?

25G SFP28: What Makes It Different?

Driven by the increasing demand for bandwidth requirement, the 25G Gigabit Ethernet or 25GBASE-T standard has been released in recent years. Then 25G SFP28 assemblies like SFP28 transceiver and SFP28 DAC & AOC, come into being. Though the SFP28 assemblies have been used in a wide variety of high-density and low-power 25 Gigabit Ethernet connectivities, they are still different in optical communications. Why? The following part will uncover it.

Benefits of 25G SFP28 Connections

To meet the growth for bandwidth in data centers, 25G SFP28 brings great benefits for system operators to achieve better network performance.

More Logical Upgrade Paths for Server Connections

Before the 25GBASE-T standard arises, the Ethernet speed upgrade path was clearly defined as 10G – 40G -100G. However, the SFP28 provides a new way for server connections: 10G – 25G- 40G -100G. And since 25G offers a more efficient use of hardware and a more logical upgrade path to 100G, many companies like Cisco, Microsoft and Intel have put it into practice rapidly.

sfp28

More Cost-Effective Cabling Choices

25G SFP28 takes existing module form factors, such as SFP28 and QSFP28, and allows for a breakout connection that is configurable as either 25G per lane or the full 100G without changing the port on the front of switches. For example, SFP28 twianx cable, also called SFP28 DAC, is a type of 25G SFP28 assembly. It has a similar structure with other DACs like SFP+ DAC or QSFP+ DAC whose connectors are not real optical transceiver. Due to this reason, SFP28 twinax cable is cheaper than SFP28 AOCs and SFP28 optical transceiver, which offers a cost-effective solution for high density, high speed I/O data center applications.

qsfp28 to sfp28 breakout cable

Furthermore, QSFP28 to SFP28 breakout cable provides various cabling choices for switches and servers. In the following figure, there are two different links between the switch and servers: 25G and 50G server links. Both of them use the 100G QSFP28 to SFP28 breakout cables.

Controversial Compatible Problem

SFP28 optics offer various options for data center and high-performance computing networks applications. However, when using them, many users still have questions about their compatibility and would like to compare them with existing optical modules. That’s one reason why it gets so much attention. This part will explain the differences between SFP28 and SFP, SFP28 and QSFP28.

SFP28 Vs. SFP+: Can I Connect SFP28 Ports With SFP+ Ports?

The answer for this question is “yes”. As we all know, SFP+ form factor is defined for 10G speeds. And it was later adopted for 25G but the electrical interface had to be upgraded to handle 25Gbps per lane. The pinouts of SFP28 and SFP+ connectors are mating compatible. Therefore, SFP28 is backwards compatible with SFP+ ports and will work sufficiently. In addition, compared with SFP+, SFP28 has increased bandwidth, superior impedance control and less cross talk in network connections. And SFP28 copper cable has significantly greater bandwidth and lower loss than SFP+ version.

SFP28 Vs. QSFP28: What Are the Differences?

Though there is a number “28” in their names, there are differences between the SFP28 and QSFP28 modules. SFP28 modules support 25Gbps per lane. While QSFP28 supports four independent lanes, and each is 25Gbps. Both of them can be used in 100G networks, but the SFP28 is applied in the form of QSFP28 to SFP28 breakout cables.

Summary

As a new-comer, the compatibility and the benefits makes 25G SFP28 different from 10G and 40G in some degree. The advent of 25G changes the connection speed of servers, and the migration path will from 25G to 50G or 100G, which in turn accelerate the development of 25G. 25G SFP28 assemblies, as an important bridge in this progress, are booming now and in the near future.

Introduction to 10GbE/25GbE/40GbE/100GbE Fiber Optic Cabling

Introduction to 10GbE/25GbE/40GbE/100GbE Fiber Optic Cabling

Technology is changing rapidly. Just when you got used to Gigabit Ethernet speeds being a fast & reliable system, someone unveiled 10GbE, 25GbE, 40GbE or even 100GbE systems a few years later. The newer and higher performing iterations are indeed the great breakthrough for telecommunication industry, but also pose difficulty in choosing network migration path—10G to 40G to 100G, or to 25G to 50G to 100G. We have described 10G, 25G, 40G and 100G Ethernet technology before, now in this blog, we’d like to introduce the four fiber optic cabling, and compare two 100G migration paths.

Cost-effective 10GbE Fiber Optic Cabling

10 Gigabit Ethernet technology defined by IEEE 802.3ae-2002 standard, is matured nowadays. Just like the “old” Gigabit Ethernet, 10Gb network can be terminated with either copper or fiber cabling. 1000BASE-T standard usually uses the Cat5e cables as the transmission media, while 10GbE bandwidth requires high grade copper cables like Cat6/Cat6a/Cat7 cables to support 10Gbps data rate. For instance, 10G SFP+ 10GBASE-T transceiver modules utilize Ethernet copper cables (Cat6a/Cat7) for a link length of 30m. SFP+ direct attach cables (DAC) and active optical cables (AOC) are also regarded as the cost-effective solutions for 10G short-reach applications. Besides 10G copper cables, there are single-mode (OS2) and multimode fiber patch cables (OM3/OM4) applied to different 10GbE IEEE standards. For the detailed information about the 10G cabling options, please see the following table.

10G fiber optic cable

As to the 10G fiber optic transceivers, there are a series of optical form factors including the XENPAK, X2, XFP, SFP+. The former three 10GbE optical transceivers were released earlier than smaller 10G form factor—SFP+ module. However, owing to their larger footprint, they are not successful on the 10G hardware market. Furthermore, SFP+ optics, compliant with several IEEE standards (SR, LR, LRM, ER, ZR and 10GBASE-T…) wins the heart of 10G end-users.

Singe-lane Design Makes 25GbE Shine

When 25G Ethernet was developed to support a single-lane 25Gbps standard in 2014, it was treated as the “new” 10GbE technology but delivers 2.5 times more data. Compared to 40GbE that was based on 10GbE, 25GbE with one lane obviously improves the port density and cost requirement. 25GbE network can support both copper and fiber optic cables, seen in the below table.Similar to 10GbE networks, 25G Ethernet physical interface specification supports several 25Gbps capable form factors, including CFP/CFP2/CFP4, SFP28 (1×25 Gbps) and QSFP28 (4×25 Gbps), which is also used for 100GbE. SFP28 25GBASE-SR and 25GBASE-LR SFP28 are two popular 25GbE optical transceiver modules available on the market, the former supports up to 100m link length while the latter allows a maximum transmission distance of 10 km.

25G optical modules

The available optical switches of the market do not support direct 25GbE connections using an SFP28 direct attach copper (DAC) cable. It is recommended to use a breakout cable that allows four 25GbE ports to connect to a 100GbE QFSFP28 switch port. FS.COM SFP28 DAC cable lengths are limited to four meters (1m, 2m, 3m, 5m) for 25GbE. And if you prefer a longer length, the 25GbE active optic cable (AOC) solutions are good recommendations.

25G Optics SFP28 Type
Media/Reach
All 25G SFP28 Ports 25GBASE-SR 50µm MMF / 70m
25GBASE-LR 9µm SMF / 10km
25GBASE-AOC Pre-terminated in 3, 5, 7, 10, 15, 20, 25, 30m lengths
OM4 MMF MTP/MPO 150m
25G Copper SFP28 Type Media/Reach
All 25G SFP28 Ports 25GBASE-CR Twinax / ‘Direct Attach’ Pre-terminated in 1m, 2m, 3m, 5m lengths

 

Fast & Reliable 40GbE Fiber Optic Cabling

Like the 10GbE fiber optic cabling, there are several IEEE standards of 40GbE transceiver in the whole evolution. 40G QSFP+ optical transceivers are the most commonly used optics for 40G network. So how to choose fiber optic cables for 40G optical transceivers? The following table will help you out.

40G modules

Besides the QSFP+ fiber transceivers and fiber optic cables, 40G DAC cables available in QSFP+ DAC cables and AOC cables enable short-reach options. For 40G cabling, QSFP+ to QSFP+ (40G to 40G) and QSFP+ to 4SFP+ (40G to 10G) breakout cables satisfy customers for various fiber types and reach requirements.

100GbE Fiber Optic Cabling For Future Proofing

With the price of 100G optics cutting down in 2017, 100GbE network is no longer out of customers’ reach. Telecom giants like Cisco, Arista, HPE launches series of 100G optical switches to meet the market demand. And for other 100G components like 100G optical transceivers, fiber patch cables, racks & enclosures, etc, those are ubiquitous on the market.

100G optical transceivers including the CFP, CFP2, CFP4, CXP and the most popular 100G QSFP28 optics in IEEE standards provide a great selection to the overall users.For 100G inter-rack connections, QSFP28 to QSF28 Direct Attach Copper (DAC) Cables and Active Optical Cables (AOC) as well as the QSFP28 to SFP28 breakout cables are the cost-effective solutions.

Path 1: 10G to 40G to 100G

Many of the largest data centers has already moved to 40GbE, which are constructed out of 4 parallel SerDes 10Gb/s links between the Ethernet chip and the QSFP pluggable. The short-reach QSFP interfaces (QSFP+ SR4 modules) use 4 pair of fiber between them, and the copper Direct Attach Cable (DAC) equivalent carry the same on several copper cables inside the big cable. Longer-reach QSFP interfaces (QSFP+ LR4 optics) put the 4 10Gb/t streams onto separate Wave Division Multiplexing (WDM) waves which can be carried over a single pair of fiber. This is part of the reason why QSFP optics are fairly expensive still, especially for longer distances.10GbE to 40GbE to 100GbESimilarly for the 100GbE interfaces that are available today, these are really constructed out of 10 parallel paths of 10Gb/t streams. 100G SR10 modules is the optical transceiver modules that support 10×10Gb/s modes. But neither the CXP SR10 modules or CFP 100G SR10 optics are not popular on the 100G hardware market owing to their larger form factors. Eventually, they need to utilize the smaller footprint 100G modules—QSFP28 transceiver, which is mentioned above as the optical transceivers that can be used in 25GbE and 100GbE.

Result: Although the migration path from 10G to 40G to 100G requires more ports and increases cost per bit, 40GbE between switches is expected to be remain and will not be affected in the near future.

Path 2: 25G to 100G—The Move From 10 Lanes to 4

The old transition path of Ethernet has increased by 10X in speed like the 10G to 40G to 100G. However, 25 Gbps over a single lane for server makes 100G migration be 4×25Gb/s mode.100-gbe-block-diagramUsing four-lane variants like QSFP28 is more economical in several ways:

  • The single-lane design makes four 25 Gbps lanes transceivers less expensive than ten 10Gbps lanes because the transceiver is simpler and less costly to manufacture.
  • The power required to run SFP28 transceivers is much less than required for a typical 10-lane transceiver, it is the same case as the cooling costs.
  • For fiber connections, moving from 10GbE to 40GbE may require an upgrade to four times the number of fibers (MPO), but a 25GbE connection does not because it is the same as 10GbE (single TX and single RX, not four each for TX and RX).
  • Moving from 10GbE to 40GbE typically requires a forklift upgrade to thicker, more expensive cables, but a 25GbE direct attach copper connection does not.

Result: There are few switches and NIC cards that directly support 25GbE. But the curve for 25GbE won’t fade away, rapid development and pre-standard 25GbE products coming soon!

Conclusion

This article introduces 10G/40G/100G fiber optic cabling, and make a clear comparison between the two paths to 100GbE. Customers prefer 4×25Gbps for the reasons: Less parallel paths, less fibers, less optics, less everything. For those who want to upgrade from 40G to 100G, appreciate the reliable performance of 40G with the potential to run across 2 parallel 25Ghz rather than 4 required today.

10G Ethernet SFP+ Vs. 10G Fibre Channel SFP+

10G Ethernet SFP+ Vs. 10G Fibre Channel SFP+

Today’s technology presents unprecedented migration incorporating a wide range of application requirements such as database, transaction processing, data warehousing, integrated audio/video, real-time computing, and collaborative projects. Fibre Channel and Gigabit Ethernet, both are the ideal solutions for IT professionals who need reliable, cost-effective information storage and delivery at fast speeds. Fibre Channel is available in 1G/2G/4G/8G/16G FC and 10GFCoE, 40GFCoE and 100GFCoE nowadays. Gigabit Ethernet is the reigning network for data center and server room. The battle between Fibre Channel and Ethernet is complicated. However, this article will help you solve it out by comparing 10G SFP+ Fibre Channel transceiver modules and 10G Ethernet SFP+ modules.

Encoding Mechanisms of Ethernet and FC

Any time we’re transmitting or storing data, we encode it in some form or another. Then we need to understand the encoding mechanisms of Ethernet and FC.

1, 2, 4, and 8 Gb Fibre Channel all use 8b/10b encoding. Meaning, 8 bits of data gets encoded into 10 bits of transmitted information, the two bits are used for data integrity. For example, Original 1Gb FC is actually 1.0625Gb/s, and each generation has kept this standard and multiplied it. 8Gb FC would be 8×1.0625, or actual bandwidth of 8.5Gb/s. 8.5*.80 = 6.8. 6.8Gb of usable bandwidth on an 8Gb FC link.

10GE (and 10G FC, for that matter) uses 64b/66b encoding. For a 10Gb link using 64b/66b encoding, that leaves 96.96% of the bandwidth for user data, or 9.7Gb/s.

10G SFP+ Fibre Channel Transceiver Module

10G SFP+ Fibre Channel (FC) transceiver, as the name implies, is the 10G optical transceivers used for Fibre Channel applications. 10G FC SFP+ module has the same footprint as SFP form factor and is compliant with MSA SFF-8431. 10G SFP+ Fibre Channel transceivers uses the either the 850nm VCSEL as the transmitter fro multimode fiber or 1310nm/1550nm laser as the transmitters for single-mode fibers in SONET OC-192 /SDH, 10GBASE-SW, 10GBASE-LW, 10GBASE-EW, and 10GBASE-ZW applications.

Cisco DS-SFP-FC10G-LW

Cisco DS-SFP-FC10G-LW, seen in the above image, is the long-range single-mode 10G SFP+ FC optical module for a link length of 10km over 1310nm wavelength. 10GFC is backward compatible with previous generation 8G/4G/2GFC and will auto-negotiate down to the fastest speed supported by both ports. This allows 10GFC devices and switches to be seamlessly integrated into expansion segments of existing FC networks without a forklift upgrade.

10GBASE SFP+ Ethernet Transceiver Module

SFP+ 10G modules is the optical transceiver for serial optical communication applications at 10Gbps. Unlike the SFP+ FC transceivers, 10GBASE SFP+ Ethernet modules can use either copper or fiber cabling. SFP+ 10GBASE-T optical transceiver supports Cat6 RJ45 copper cables for a link length of 30m. 10GBASE SFP+ Ethernet modules are available in several 10 Gigabit Ethernet standards like 10GBASE-SR Ethernet, 10GBASE-LR, 10GBASE-LRM, 10GBASE-ER, 10GBASE-ZR, and 10GBASE-T.

HPE 10G SFP+ module

Cisco SFP-10G-LR is the 10km Cisco 10GBASE-LR SFP+ module that uses 1310nm as the transmitter type over single-mode fiber cables. 10GBASE-LR SFP+ modules cannot be auto-negotiate with 1000BASE SFP transceivers, but for most switches, SFP+ ports can support 1G SFP modules for 1Gbps data rate.

Comparison Between 10G Fibre Channel SFP+ and 10G Ethernet SFP+

From the previous description, we can easily draw a conclusion that 10G Fiber Channel SFP+ and 10G Ethernet SFP+ share several specification in common.

  • Footprint

They have the same form factor as 1000BASE SFP transceiver modules.

  • Performance

Except the application, 10G Fiber Channel SFP+ SW module and 10Gb SR SFP+ transceivers have the very similar functions with each other. For the exact information, please see the following table.

Part Number Wavelength Media Distance Application Connector Voltage
10G SW SFP+ 850nm (VCSEL) MMF 300m/OM3 10GBASE-SR/SW Ethernet, 10G Fibre Channel LC Duplex 3.3V
10G LW SFP+ 1310nm SMF 10km 10GBASE-LR/LW Ethernet, 10G Fibre Channel LC Duplex 3.3V
10G EW SFP+ 1550nm SMF 40km 10GBASE-ER/EW Ethernet, 10G Fibre Channel LC Duplex 3.3V
10G ZW SFP+ 1550nm SMF 80km 10GBASE-ZR/ZW Ethernet, 10G Fibre Channel LC Duplex 3.3V
  • Application

10G Fiber Channel SFP+ is used in 10G Fibre Channel, yet 10G Ethernet SFP+ is utilized in 10G Ethernet networks.

2017 Prediction of Ethernet and Fibre Channel

Without denying, Ethernet is the dominating network for every data center and server room. The “old” Ethernet network—1Gb/s and 10Gb/s speeds relied heavily on TCP to deliver data, which was reliable but somewhat unpredictable. However, today’s Ethernet runs at 25, 40, 50, or 100Gb/s speeds, is no longer dependent on TCP alone. It also supports RDMA connections which lower latency and frees up CPU cycles to run applications. 100Gb/s technology is quite matured in 2017 and there are many relevant devices available on the market, such as CFP/QSFP28 optical transceivers, 100G switches and network interface cards, 24 fiber MTP cables, etc.

Fibre Channel Vs. Gigabit Ethernet

Meanwhile, FC is still transitioning to 16/32 Gb/s technology (32Gb/s is not mature), which is quite slower than what Ethernet was supporting several years ago. For 32Gb/s FC network, it still supports only block storage traffic. Other storage (and other non-storage) traffic will require an Ethernet network anyway.

If we look at what is coming in 2017, the battle will not be 10/40/100GbE Vs. 8/10/16/32Gb FC. Almost everyone would agree that it would be nice to have a single network for all traffic, and very few users want a new protocol and the challenges of changing the way that they do things.

Conclusion

FC or Ethernet, which is best for storage? 10Gb FC SFP+ has the same usable bandwidth as the 10Gb Ethernet SFP+, and without the overhead of FCoE, but you don’t get the consolidation benefits of using the same physical link for your storage and traditional Ethernet traffic. FS.COM offers reliable 10G SFP+ transceivers in Ethernet, FC, BiDi, CWDM/DWDM applications. If you are interested in our products, please contact us directly.