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Will CPAK 100G Transceiver Module Thrive in 2017?

Currently, prices on 100G optical transceivers have been dropping faster than those devices at 40G, which drives customers to migrate to 100G directly instead of turning to the intermediate 40G Ethernet. For example, QSFP-40G-SR-BD ($300) costs higher than QSFP-100G-SR4-S ($269) at FS.COM. It is the same case as other vendors. QSFP28 and CFP optical transceivers as the main transmission media of 100G network, dominate 100G hardware market.

100G transceiver modules

CPAK, released right after CFP2 100G modules, is the Cisco proprietary form factor, which greatly effect the popularity of this module type. However, in 2017, many third party optical solution vendors like FS.COM announce to help market to cut down this pricing and save budgets for services providers and operators. So will it thrive in 2017? Today’s article will describe CPAK 100G module in detail attached with the positive analytics of the future of this module type.

Unveiling CPAK Optical Transceiver Module

CPAK 100GBASE optical module, designed as a smaller, low-cost alternative to CFP transceiver, can be plugged into the CPAK ports of Cisco switches and routers. Besides, CPAK module is the first 100G optical transceivers that use CMOS Photonics technology. This type of 100GBASE modules can work in the following Cisco networking equipment—ASR 9000 Series Router; CRS-X Carrier Routing System; NCS 2000, 4000, and 6000 Series Routers; the Nexus 7000 and 7700 Series Switches, and the Cisco ONS Transport Platform.

CPAK optical transceiver incorporates IEEE standard interfaces available in several different types: 100GBASE-SR10, 100GBASE-ER4L, 100GBASE-LR4, 10x10G-ERL, 10x10GBASE-LR, etc. CPAK transceivers can support 10X10Gbps and 4X25Gbps mode for an aggregate of 100Gbps data rate. It can also operate high-density 10G breakout with MPO-24 cables. CPAK-100G-SR10 is backward compatible with 10GBASE-SR. While CPAK 10X10G-LR is compatible with 10GBASE-LR optics. CPAK LR4 module is compatible with other 100GBASE-LR4 compliant modules such as CFP to support high-bandwidth 100Gb optical links over standard single-mode fiber terminated with SC connectors. Table 1 shows the existing Cisco 100G CPAK Modules.

Cisco CPAK modules

CPAK Out-Competes CFP/CFP2 for Smaller Footprint & Energy Economy

Once the CPAK transceiver module had been released, it was marked as the smallest 100G footprint providing higher-port density and low power consumption for 100G networks. When comparing with CFP modules, CPAK transceivers are less than one third the size of CFP modules, and dissipate less than one third the power. In a comparison with CFP2 modules, CPAK optical transceivers are 20% smaller and consume 40% less power. In other word, if you use CPAK other than CFP2 modules in your data center switches, it can offer 20% greater port density and front-panel bandwidth.

100G-module-evolution

To sum up, CPAK optical module has smaller footprint than CXP, CFP and CFP2, but bigger than CFP4 and QSFP28 optics. Besides, CPAK 100GBASE-LR4 consumes less than 5.5W, which is less than CFP LR4 (24W), CFP2 LR4 (12W), CFP4 (9W) and CXP LR4 optics (6W) but a little higher than QSFP28 (3.5W). CPAK represents a significant advancement in optical networking, providing dramatic space and power efficiency.

CPAK Vs. QSFP28

QSFP28 optical transceiver is regarded as the most promising 100G optical module due to its smallest form factor and lowest power consumption. For example, Cisco CPAK 100GBASE-LR4 module supports link lengths of up to 10 km over standard single-mode fiber with SC connector with a nominal power consumption of less than 5.5W. QSFP28 100GBASE-LR4 supports up to 10km and consumes nearly 3.5W. CPAK optics obviously don’t have a shot when competing with QSFP28 optical transceivers.

What About the Future of CPAK Modules?

In 2017, 100G technology and relevant optical transceivers gradually become mature. 100G optics like CXP, CFP/CFP2/CFP4, 100G QSFP28 in different standards offers a huge selection for customers. Of which QSFP28 100G modules, thanks to the smallest form factor and reliable performance, maintain large market share in 100G hardware market. In addition, some newly released 100G switches only have QSFP28 ports which in turn promotes the popularity of 100G QSFP28 transceivers.

In such a fierce market environment, it is hard to say whether CPAK will be a hot star in 100G hardware market or not. Anyhow—CPAK module is the first optical transceivers that use CMOS electronic technology. Furthermore, Cisco and several other vendors offer CFP2 to CPAK adapter to support the conversion between CPAK and CFP2 modules. Third party vendors like ourselves are also beginning to supply 100G CPAK modules in 2017. We will see if such industry development will take place!

Summary

CPAK module was launched just days after the certification of CFP2 optics. It is popular for the smaller footprint and energy economy. However, when competing with open source MSA compatible 100G products (CFP/CFP2/CFP4 and QSFP28), CPAK is not the ideal one for 100G high-density connectivity. The world undergoes a myriad changes in the twinkling of an eye. For the newly information about our new-coming CPAK modules, please visit fs.com or pay attention to the updated article in this blog.

Original Source: Will CPAK 100G Transceiver Module Thrive in 2017?

How to Choose Fiber Optics for Mellanox ConnectX Ethernet Adapter Cards?

Mellanox ConnectX Ethernet adapter card provides high-performance networking technologies by utilizing IBTA RoCE technology, delivering efficient RDMA services and scaling in ConnectX-3, 4, 5, 6 EN 10/25/40/50/56/100/200GbE connection. The Mellanox ConnectX EN Ethernet card supports a full suite of software drivers like Microsoft Windows (including Windows 10), Linux distributions, VMware and Citrix XenServer. ConnectX Ethernet adapter card comes in several types for 10/25/40/50/56/100/200GbE network, such as ConnectX-3 EN, ConnectX-3 Pro EN, ConnectX-3 Pro EN 10GBASE-T, ConnectX-4, ConnectX-4 Lx EN, ConnectX-5 EN, ConnectX-6 EN adapter cards. In this article, we present an in-depth network-level performance evaluation of the Mellanox ConnectX Ethernet adapter cards and the supported fiber optic cabling.

Mellanox ConnectX Ethernet Adapter Card

Network Interface Card (NIC), also known as Network Interface Controller, Network Adapter, LAN Adapter or Physical Network Interface. All Mellanox 10/25/40/50/100/200 Gigabit Ethernet adapters deliver high-bandwidth and industry-leading Ethernet connectivity in enterprise data centers, high-performance computing, and embedded environments. From ConnectX-2 to ConnectX-6, Mellanox keep upgrading their Ethernet adapter cards to meet customers requirement.

Connectx-6 EN

ConnectX-6 EN—200Gb/s Adapter Card

ConnectX-6 EN 200Gb/s Adapter Card, launched last year, was the world-first 200Gb/s Ethernet network adapter card for Ethernet connectivity, sub-600 ns latency and 200 million messages per second. ConnectX-6 EN, seen in the image, provides two ports of 200Gb/s for Ethernet connectivity. As the first adapter to deliver 200Gb/s throughput, ConnectX-6 is the perfect solution to provide machine learning applications with the levels of performance and scalability that they require.

ConnectX-5 EN—Adapter Supporting 100Gb/s EthernetConnectX-5

ConnectX-5 just as the image shows, supports two ports of 100Gb/s Ethernet connectivity, sub-700 nanosecond latency, and very high message rate, plus PCIe switch and NVMe over Fabric offloads, providing the highest performance and most flexible solution for the most demanding applications and markets.

Table 1 presents the detailed information about Mellanox ConnectX-5 EN Ethernet Adapter Cards

Ordering Part No.
Description
Speed Ports Connectors Dimensions w/o Bracket
MCX515A-CCAT 100GbE single-port QSFP28, PCIe3.0 x16, tall bracket, ROHS R6 100GbE 1 QSFP28 14.2cm x 6.9cm (Low Profile)
MCX516A-CCAT 100GbE dual-port QSFP28, PCIe3.0 x16, tall bracket, ROHS R6 100GbE 2 QSFP28 14.2cm x 6.9cm (Low Profile)
MCX516A-CDAT 100GbE dual-port QSFP28, PCIe4.0 x16, tall bracket, ROHS R6 100GbE 2 QSFP28 14.2cm x 6.9cm (Low Profile)
ConnectX-4 EN—Adapter Supporting 10G/40G/100Gb/s

ConnectX-4 LX ENConnectX-4 adapter cards have three different types: ConnectX-4 Lx EN Programmable Adapter Card, ConnectX-4 EN, ConnectX-4 Lx EN. ConnectX-4 Lx EN Programmable Adapter Card is listed in the right image. ConnectX-4 EN network is the single or dual port 100 Gigabit Ethernet adapter cards. ConnectX-4 Lx enables data centers to migrate from 10G to 25G and from 40G to 50G speeds at similar power consumption, cost, and infrastructure needs. If you are into this NIC card, you’d better look through their difference.

ConnectX-3 Pro EN—10/40/56 Gigabit Ethernet Network Interface Cards

ConnectX-3 Gigabit Ethernet interface card is one of the mostly used NIC cards nowadays. This kind of NIC card can support 10/40/56Gb/s Ethernet connectivitConnectX®-3 Pro Programmable Adapter Cardsy with hardware offload engines. The long-term goal at Mellanox ConnectX Gigabit Ethernet adapter card is to allow customers to wire once and switch protocols on the server and switch as required by workloads. Mellanox can presumably charge a premium for such capability, and ConnectX-3 silicon allows Mellanox to create fixed adapters and switches at specific speeds to target specific customer needs and lower price points, too. The image on the right display the ConnectX-3 Pro Programmable Adapter Cards.

For detailed information about ConnectX-3 Pro EN adapter cards, please see the Table 2.

Ordering Part No.
Description
Dimensions w/o Bracket
ConnectX-3 Pro EN Adapter Cards
MCX311A-XCAT Single 10GbE SFP+ 10.2cm x 5.4cm
MCX312A-XCBT Dual 10GbE SFP+ 14.2cm x 6.9cm
MCX313A-BCBT Single 40/56GbE QSFP 14.2cm x 5.2cm
MCX314A-BCBT Dual 40/56GbE QSFP 14.2cm x 6.9cm
ConnectX-2—Supporting 10G Ethernet Switches

ConnectX-2 Gigabit Ethernet Cards

Mellanox ConnectX-2 EN cards are the older cards for Ethernet only. That means that they will not work in Infiniband networks. In fact, there are still a few examples of OSes without ConnectX-2 support. Prime examples are FreeBSD 9.3 based FreeNAS and NAS4Free versions which did not have built-in support for the cards. The bottom line is that in terms of compatibility, one does need to verify these cards will work.

Many customers do use these in their Windows 10 home workstation for a 10Gb SFP+ back-haul network. Speeds are reliable and excellent. Nowadays, Mellanox does not supply this card, but ebay and Amazon do provide ConnectX-2 cards under $19.

How to Choose the Cables and Optical Modules for ConnectX-3 Ethernet Adapter Cards?

According to Mellanox, ConnectX-3 10G/40G/56G Ethernet adapter cards are interoperable with 10/40 Gb Ethernet switches. Passive copper cables with ESD protection are supported in this NIC card. ConnectX-3 cards can support up to 56Gb/s that can accommodate several fiber cables and optical transceiver types. Take the MCX313A-BCBT as an example, it has single 40GbE QSFP+ port. QSFP+ optical transceivers and DAC cables are feasible in this Ethernet Adapter Card. For the 10G SFP+ to 40G QSFP+ migration, Mellanox QSA (QSFP+ to SFP+) modules are required.

QSA Module

A previous article QSFP+ to SFP+ Adapter (QSA) Module Vs. QSFP+ to SFP+ Breakout Cable provides the detailed information about how to use the QSA module.

DAC Twinax or 10GBASE-T Copper Cable For ConnectX-2 NIC Cards

Mellanox ConnectX EN Gigabit Ethernet Cards can support up to 200Gbps data rate. Each ConnectX adapter card, as mentioned above, supports optical transceivers and modules applied for 10G/25G/40G/100G Ethernet network. ConnectX-2 EN Ethernet card, for example, can be used for 10GbE networks. Except the expensive SFP+ optical transceivers, SFP+ DAC Twinax and 10GBASE-T copper cables are the commonly used  transmission media for 10G data center inter-rack and TOR switching. So how to choose between them?

DAC Twinax Cable

DAC SFP+ Twinax cables integrates SFP+ modules and Twinax cables on the same conduit. It uses the SFP+ optical transceiver modules as connectors (not the real transceiver) on both ends so as to provide a cost-effective and low-power consumption solution for data center interconnection. 10G DAC Twinax cables can be divided into two types: active DAC twinax and passive DAC cables. For distances >5m and <10m, pickup the active version. Otherwise passive direct attach copper cables should be fine.

SFP+ DAC Twinax cables in NiC

Fiberstore is one of the best vendors for DAC and other fiber optics. Their packaging and after-sale support for even the smallest orders is excellent. For connecting two ConnectX-2 cards together, you can get one of the SFP+ copper cables.

Ethernet Network Cables

Ethernet Network Cables like Cat5, Cat5e, Cat6 do look alike from the outside and they all use the same connectors as well. However, they have significant differences on the inside. One simple method is that you can find out the type of cable you have by looking at the text printed on the side of the cable. There are other cables possible (like Cat7 and Cat8 cables) but Cat5, Cat5e, Cat6 cables are the most common now.

  • CAT5

Category 5 cabling is an older type of network cabling compared with Cat5e and Cat6 cables. Cat5 cables support transfer speeds of 10/100 Mbit/s (Fast Ethernet). Nowadays, many installers treat it as old and obsolete and try not to use it. For those who buy cat5 cables,  they tend to use in older devices such as an older router or switch.

  • CAT5e

Category 5 enhanced (Cat5e) cables currently are the most commonly used Ethernet network cables owing to its enhanced transmission data rate and reduced crosstalk. Cat5e cabling supports 1000 Mbit/s and cust down on external and internal crosstalk. It basically means that Cat5e is better at keeping signals on different circuits or channels from interfering with each other.

  • CAT6

Category 6 cabling (Cat6) supports 10 Gbit/s speeds with additional crosstalk improvements. If you’re purchasing a new cable for future proofing,  it should really be CAT6 or above. That doesn’t imply Cat6 cables protect your network from the future or anything, it just means it will keep it up to date for longer when the next products comes along.

Note : Your network speed depends on  the slowest part of your setup. If you want to deploy gigabit ports, gigabit routers, switches,  then please make sure you cabling also supports those speeds as well.

Summary

Mellanox is the world-class vendor for selling multi-protocol chips and adapter cards for servers. It provides a wide range of high-speed interconnection solutions including Gigabit Ethernet cards and InfiniBand adapter cards. The above mentioned ConnectX Gigabit Ethernet cards can not be used in InfiniBand networks. ConnectX Mellanox Gigabit Ethernet cards are the cost-effective devices for your network applications. If you do have the Mellanox NIC cards, you can buy the cost-effective DAC and optical transceiver modules from FS.COM to further reduce the total cost of your budget.

Several 100G DWDM Solutions for Arista 7500E Series

To keep up with the global demand for higher bandwidth, Arista has designated 7500E series switch to address 100G long-hual dense wavelength division multiplexing (DWDM) connectivity. Arista 100G interconnect solution combines Layer 2/Layer 3 switching, wire-speed encryption and coherent DWDM into a high-density line card for the Arista 7500E data centers. Along with the introduction of Arista 7500E series switches, this article will illustrate several 100G DWDM solutions for distance up to 80 km, 150 km and 3000 km as well.

Arista 7500E Series Switch & Line Card

Arista 7500E series is the second generation of 7500 series switch that delivers scalable and deterministic network performance for mission critical data centers, enterprise and HPC environments. Available in a compact 7RU (4-slot) or 11RU (8-slot), Arista 7500E offers over 30Tbps of total capacity for 1,152 ports of 10GbE, 288 ports of 40GbE and support for 96-port 100GbE with a broad choice of interface types that support flexible combinations of 10G, 40G and 100G modes on a single port.

The 7504 and 7508 are the two types of Arista 7500E series switches. The 7508 systems support 8 linecards, dual supervisor modules and 6 fabric modules to provide a full 30Tbps of capacity. The smaller 7504 systems share a common architecture with the 7508 with the primary difference being support for 4 linecards and 15Tbps of forwarding capacity. The most unique feature of this switch is that it can connect with 10G SFP+, 40G QSFP+, 100G QSFP28 and CFP2 modules.

arista-7500E-switch

Arista 7500E series line card for addressing 1/10G, 40G and 100G with full support for industry standard connections and comprehensive layer 2 and 3 features for flexible deployment choice. The line card delivers error-free performance up to 3000 km of fiber and consumes less than 140W per 100Gbps. Similar to any other Arista platform, the DWDM line card utilizes the single binary image of Arista’s extensible operating system (EOS). Line cards with CFP2 and QSFP support standard 100G for both single and multimode fiber for distance up to 40 km.

Why Need 100G DWDM Solution?

100G optical transceivers provide the most straightforward method to connect 100G traffic over long-hual applications. 100G optics like CFP and QSFP28 offer cost-optimized solutions for connecting 100G switches together in a rack or data center. Nevertheless, the small and cost-effective QSFP28 100G optics now can only handle connections over distances of less than 10 km. For example, QSFP28 LR4 is compliant with 100GBASE-LR4 standard that operates over duplex LC cables for a link length of 10 km.

As to the CFP form factors, coherent CFP modules is designed to support metro and long-hual DWDM applications. CFP 100GbASE-ER4 can support up to 40 km. However, owing to its large size and high power consumption, CFP transceivers are less popular on the market. If you want to use CFP optics for 100G deployment, keep in mind, CFP modules are too large to fit in the Ethernet switches and will significantly reduce port counts and increase power usage, making 100G switches poor performance in cost-effectiveness. Therefore, customers who want to upgrade 100G network can only cover a distance of 10 km, which is obviously insufficient for geographically separated data centers or metro infrastructures. Figure 2 shows the basics of DWDM system.

DWDM-System

To realize 100G long-distance transmission, Arista 100G DWDM solution combines DWDM optics with a fully passive Mux/Demux system that can handle up to 3,000 km. Arista 100G DWDM solution is a 6 x 100G Coherent DWDM line card for the 7500E series with integrated wire-speed encryption and analog coherent CFP2 optical interfaces. Several use cases for the Arista 7500E Series DWDM card in multi-site data center networks exist. The following sections identify three use cases for Arista 7500E DWDM solutions.

Use Cases for Arista 7500E DWDM Solution
  • Use Case 1—Less Than 80KM Dark Fiber Connection

For a typical metro link that is less than 80 km, Arista 7500E Series DWDM line cards can directly terminate a dark fiber connection providing a point-to-point connection between two locations.

DWDM solution for 80 km

Just as figure 3 shows, Arista DWDM solution is ideal for metro applications transmitting up to 9.6Tbps traffic without the need for any additional amplification.

  • Use Case 2—Greater Than 80 km But Less Than 150 km

When extending the distance beyond 80 km, there is a need to amplify the signal to offset heavy signal loss that occurred in the light signal when passing through fiber cables, patch panels and other optical devices. Under this circumstance, EDFA’s or Erbium Doped Fiber Attenuators are employed to give the aggregated wave a boost.

100G DWDM solution about 100 km

By using EDFAs (seen in Figure 4) to the transmit side of each end of the dark fiber link, the signal can be boosted to achieve distances of up to 150 km. Exact distances will be dependent on the number of patches, fiber splices and quality of the fiber.

  • Use Case 3—Greater Than 150 km But Less Than 3,000 km

Arista 7500E DWDM solutions can also cover the distance of greater than 150 km but less than 3000 km. Employing further EDFAs at a spacing of approximately 80 km along the fiber route allows the length of a connection to be extended to over 3,000 km. As shown below, EDFAs are used on both paths to boost the signal.

DWDM solution for 3000 km

Supported Optics for Arista 7500E Series

All Arista 10G SFP+ transceivers, with the exception of LRM, are supported on the Arista 7500E SFP+ ports.

Interface Type SFP+ ports
10GBASE-CR 0.5m-5m
10GBASE-AOC 3m-30m
10GBASE-SRL 100m (OM3) / 150m (OM4)
SFP-10G-SR 300m (OM3) /400m (OM4)
SFP-10G-LRL 1km
SFP-10G-LR 10km
SFP-10G-ER 40km
10GBASE-DWDM 80km
SFP-10G-ZR100 100km
100Mb TX, 1GbE SX/LX/TX Yes

The 40G QSFP+ transceivers and cables allow for 4x10G mode support with the use of fiber breakout cables, MTP to LC cassettes, or QSFP to SFP+ cables. See the below table for details on the latest supported 40G transceivers.

Interface Type QSFP+ ports
40GBASE-CR4 0.5m-5m
40GBASE-AOC 3m-100m
QSFP-40G-UNIV 150m (OM3) / 150m (OM4), 500m (SM)
QSFP-40G-SRBD 100m (OM3) /150m (OM4)
QSFP-40G-SR4 100m (OM3) / 150m (OM4)
QSFP-40G-XSR4 300m (OM3) / 400m (OM4)
QSFP-40G-PLRL4 1km (1km 4x10G LR/LRL)
QSFP-40G-PLR4 10km (10km 4x10G LR/LRL)
QSFP-40G-LRL4 1km
QSFP-40G-LR4 10km
QSFP-40G-ER4 40km

100G QSFP28 and CFP2 Optics

Interface Type 100G CFP2 Ports 100G QSFP Ports
100GBASE-XSR10 300m OM3 / 400m OM4 Parallel MMF
100GBASE-SR4 100m OM3 / 150m OM4 Parallel MMF
100GBASE-LR4 10km SM Duplex 10km SM Duplex
100GBASE-LRL4 2km SM Duplex
100GBASE-ER4 40km SM Duplex
100GBASE-CWDM4 2km SM duplex
100GBASE-PSM4 500m SM Parallel
100GBASE-AOC 3m to 30m
100GBASE-CR4 1m to 3m
Conclusion

Arista 7500E DWDM solution works in conjunction with passive Optical Mux/Demux devices and in-line amplifiers to support additional bandwidth and extended reaches. Arista 7500E DWDM solution can directly reach up to 80 km without requiring in-line amplification, which is ideal for metro applications. With an Optical Signal to Noise ratio (OSNR) of 11.6dB, it can be used effectively for point to point long-haul applications up to 3,000kms with in-line amplifiers and multiplexers.

Related article : How to Deploy QSFP28 Modules for 100G Deployment

SFP and SFP+ Compatibility Issues

Recently, People have gotten the question about whether I can use the SFP transceivers in a 10g SFP slot. Users who purchase a 10G switch wondered if they could use SFP modules in the SFP+ slot (since they both have the same size and use the LC connectors) to achieve 1G data rate. Or can I use the SFP+ modules in SFP slot to have the 10G data links? To deal with this doubt, researches have been made to provide the objective solutions here.

In Most Cases, SFP Can be Plugged into SFP+ Ports

If you are asking if an SFP+ port will accept an SFP, then the answer is almost certainly yes. Not all SFP transceivers will be compatible with all devices though. Some device makers require that the SFP or SFP+ transceiver have a branded firmware on it. That is why some SFPs are marketed as Cisco brand or HP brand or Dell brand or whatever. The hardware is all from the same Chinese factory but before they are shipped they are loaded with a firmware that marks them as being compatible with a particular brand of device. You don’t need the same brand of transceiver at both ends unless you use the same brand of switch on both ends. The transceiver should be purchased to be compatible with the device you are inserting it into (not connecting the cable to). This isn’t always necessary, only some devices have strict compatibility requirements. However, you really never know until it is too late so make sure you buy your SFPs from somewhere that will assure the compatibility and has a good return policy.

sfp-10g

The most I have had to do to make an SFP work in an SFP+ slot is to configure the interface before inserting the SFP. Sometimes you have to tell the switch/router vendors that the port is going to run at 1000 megabit before you insert the SFP.

SFP+ Can’t Auto-negotiate to Support SFP Module

Most SFP+ ports accept SFP optics, but it can’t auto negotiation to the 1G SFP modules. In fact, most (95+%) SFPs and SFP+s will only run at the rated speed, no more, no less. Besides, there is no such thing as a SFP+ that does 1G on one side (towards the fiber) and then does 10G on another side (towards the unit). Though we can use SFP in SFP+ ports in many cases, that doesn’t mean a SFP+ plugged into the SFP port can support 1G. For example, a Cisco Meraki SFP-10GB-SR can only support 10G data rate plugging into a SFP+ slots in the 10G switch.

1g-connect-to-10g

Additionally, in a fiber link, if we plug a SFP in the SFP+ port on one side (1G), and then plug a SFP+ in the SFP+ port on the another side (10G), this may not work! You just can’t have 10 GbE at one end and 1 GbE at the other. For this question, if you use SFP+ copper twinax cable, it also can’t negotiate down to 1G.

Conclusion

To sum up, the SFP+ slots will take 1Gb SFP optics though, SFP modules can not be connected with SFP+ optics. And make sure you use the same fiber link at the both ends in a fiber optic network. This is actually a complex question, there is no exact answer now. Always remember to talk with your vendors first before making the next move, or you will end up with an error. FS.COM as a professional telecom supplier, offers a full range of optical devices including fiber optic cables, optical transceivers (SFP/SFP+/QSFP+/CFP, etc.), fiber patch panels, DAC/AOC cables. If you want to know more about our company, please contact us directly.

Will Single-mode Fiber Work Over Multimode SFP Transceiver?

Network installers usually come across a situation that device you have in your network does not always fit and work perfectly with the fiber. They plan to make a cable plant based on the multimode cabling, but owing to the link limitation or other reasons, they have to connect multimode equipment with single-mode devices. Is it feasible? Or put it more specifically, can I use the multimode SFP over single-mode fibers or vice versa? This article will give you a detailed illustration about the feasibility of the solutions, and introduce two relevant devices (mode conditioning cable and multimode to single-mode fiber media converter).

Single-mode Fiber Over Multimode SFP—You Can If You Are Lucky

This is the question that has been asked so many time, but no one can give the exact answer—yes or no. Hence, let’s illustrate it in details.

Most people think single-mode and multimode fibers are not interchangable because of the wave length of the laser and core size of the fiber. Single-mode fiber (MMF) uses a laser as a light source (the light beam is very concentrated), while multimode fiber (MMF) uses an LED to generate the signal. This would require two significantly different devices to generate the signal.

The core sizes are drastically different between SMF and MMF. SMF is 9 micron and multimode is 62.5 or 50 micron. If users try to mix the single-mode and multimode cabling in the same network, they might have trouble dealing with the two different types of signal.

However, it is possible to interconnect two devices using SMF interfaces at one end and MMF receiver at the other end. Keep in mind that it depends on the devices, so you can if you are lucky. When plugging LC single-mode duplex fibers on the multimode fiber transceiver (1000GBASE-SX) in the network, you will find the link came up (the light on the switch turns green). Therefore, the multimode fiber transceiver connected by the single-mode fibers works for short-reach application. The following image is the real screenshot of the single-mode fibers inserting into the 1000BASE-SX SFP.

real screenshot of inserting single-mode fiber over multimode fiber transceivers

While it should be stressed that the link is not reliable and it only works for particular brand devices with a very short link length. Many sophisticated vendors like Huawei, Alcatel or Cisco do not support it. Nevertheless, owing to the differential mode delay (DMD) effect, signal loss of this connection is not acceptable, either.

To sum up, this might be feasible but not advisable. If you need to make a connection between single-mode and multimode interfaces, you’d better use the intermediate switch that is able to convert the signals between single-mode and multimode fibers. The following part will introduce two solutions that might be helpful for the multimode and single-mode conversion.

Solution 1: MCP Cable—Single-mode In and Multimode Out

As to the multimode fiber with single-mode SFPs, most people mention the mode conditioning patch (MCP) cables. The MCP cable is launched to support 1000BASE-LX optics over multimode cable plant. The mode conditioning cables allow customers to successfully run Gigabit Ethernet over our multimode cable using single-mode fiber transceivers, Cisco 1000BASE-LX/LH SFP is the special type of transceiver that can both support single-mode and multimode fibers. The image below displays the difference between standard SC multimode patch cable and SC mode conditioning patch cable.

comparison between standard SC multimode fiber patch cable and SC MCP cable

Then, in this situation, you can run successfully from a single-mode fiber transceiver over multimode fiber with the use of MCP cables, but the distance will not exceed the link specification for multimode transceivers. Otherwise, there will be much signal loss in the cable run.

In general, if you want to run multimode fiber optic cable over 1000BASE-LX SFPs, you can use the mode conditioning cable. However, mode conditioning patch cords are required for link distances greater than 984 feet (300 meters). For distance less than 300 m, please omit the mode conditioning patch cords (although there is no problem using it on short links).

Solution 2: Fiber to Fiber Media Converter—Conversion Between Multimode and Single-mode Fibers

As noted before, mode conditioning cables, to some extent, can realize the connection between single-mode to multimode, but you can not say that you can convert single-mode to multimode or vice versa. Mode conversion between multimode and single-mode fibers often requires fiber to fiber media converters or the single-mode to multimode fiber converter.

F2F-10G-Multimode-to-Single-mode

In the above diagram, two Ethernet switches equipped with multimode fiber ports are connected utilizing a pair of fiber-to-fiber converters which convert the multimode fiber to single-mode and enable network connectivity across the distance between Gigabit switches.

Conclusion

It doesn’t really make much sense to use the single-mode fiber transceivers with multimode fibers in your network or vice versa, although the link will come up. Like I said above, you can if you are lucky connect. MCP cables and fiber to fiber converter are the two available options for single-mode and multimode connection. If you bought the wrong fiber optic cables, just replace it into the right one. Fiber optic cables and optical transceivers modules nowadays are very cheap. You won’t need to risk of mixing them in the same network.

Original Source : Single-mode Fiber Work Over Multimode SFP Transceiver

QSFP+ to SFP+ Adapter (QSA) Module Vs. QSFP+ to SFP+ Breakout Cable

People frequently ask about feasible solutions between 10G and 40G servers. QSFP+ breakout cables like QSFP+ to 4 SFP+ cables and MTP to 4 LC harness cables are the commonly used equipment to connect between QSFP+ ports and SFP+ ports. But recently, Cisco launched a new type of product—QSFP+ to SFP+ Adapter (QSA) module that could provide a smooth migration to 40 Gigabit Ethernet. Is it a better solution for the 10G to 40G migration? Should I use the QSA module or 40G QSFP+ breakout cable? This article will answer the above questions and provide some suggestions to you.

QSA Module—Is It a Better Solution for the 40G Migration?

The QSFP+ to SFP+ Adapter module, specified by Cisco, is the module built in QSFP+ form factor with a receptacle for SFP+ cable connector at the back (seen in the below image). When connecting the QSFP port to an SFP+ port, QSA module usually acts as an interface for SFP+/SFP cables. That means you can effectively plug in an SFP+/SFP optics operating at a 10 Gbps port on this module, then inserting the module into a QSFP port cage to realize the 40G Ethernet transition. QSFP+ to SFP+ adapter module ensures the smooth connectivity between 40 Gigabit Ethernet adapter and 10 Gigabit hardware using SFP+ based cabling. Therefore, once the QSA module came out in 2016, it was soon considered as the effective solutions for converting 40G ports to the 10G ports.

Cisco QSFP+ to SFP+ adapter cable

40G QSFP+ Breakout Cables Overview

People usually use either the QSFP+ to 4 SFP+ breakout cables or MTP to LC harness cables to convert the downlink 40G port of ToR (Top of Rack) access layer switch into 4x10G fan out mode, then connect to the 10G cabinet server port. QSFP+ to SFP+ breakout cable including the direct attach copper cable (DAC) and active optical cable (AOC) consists of a QSFP+ connector on one end and four SFP+ connectors on the other end. The cables use high-performance integrated duplex serial data links for bidirectional communication on four links simultaneously.

QSFP+ to SFP+ breakout cable

While the MTP to LC harness cable have one one MTP cables on the one end and four LC connectors on the other end. This type of cable is recommended to be used in the same rack within the short distance. The picture above shows the direct connectivity between the QSFP+ transceivers and SFP+ transceivers by using the MTP to LC harness cable.

QSA Module or QSFP+ Breakout Cable

In this part, I will make a comparison between QSFP+ to SFP+ adapter modules and QSFP+ breakout cables from the aspects of cost, performance and compatibility.

Cost—QSFP+ Breakout Cables Wins

QSFP+ to SFP+ adapter module is not certificated by Multi-source Agreement (MSA), but a sole source paradigm defined by few vendors. The only vendor owns its patent, so the QSA modules on the market are quite expensive. Nevertheless, QSFP+ breakout cables covered in the MSA standard, support both copper and optical connectivity, which are much cheaper than QSA modules. Cost comparison between QSA module and QSFP+ breakout cable (DAC, 1m) is listed in the below table.

cost comparison between QSA module and QSFP+ breakout cable

Performance

With QSA module, users have the flexibility to use any SFP+/SFP optics to connect to the 40Gbps data rate with a single 10G connection. However, QSA module only exists in 10G-40G speed, which also explains the reasons of its unpopularity of the market. QSFP+ to 4 SFP+ breakout cables split the 40G channel into 4x10G channel which provide four times more data transfers than QSA module does.

Compatible Switch and SFP/SFP+ Modules

QSA modules, according to Cisco, are available in 40 Gigabit Ethernet compatibility matrix. Cisco SFP/SFP+ transceivers that can be plugged into the QSA modules are concluded as Cisco 10GBASE-SR, LR, ER, ZR, DWDM SFP+, FET-10G and 10G SFP+ cable as well as SFP (1000BASE-T, SX, LX, EX, ZX). As for the QSFP+ to SFP+ breakout cables, different vendors have different compatible issues. Keep in mind that you should find the reliable fiber optic transceiver manufacturers.

Reminder:

  • Before using the QSA modules or the QSFP+ breakout cables to connect a 40 Gigabit Ethernet port to a 10 Gigabit SFP+ port, you must enable the fan-out mode of your devices.
  • Not all the 40G cards and switches can be split into 4x 10Gb mode, for example, the Mellanox QSFP cards do not support the QSFP to SFP+ breakout, but their switches can.
  • With the QSA module, you can directly use the SFP+ modules in a QSFP+ port, but you cannot use the QSFP+ optical cables in a QSA setup.
  • Telecom industry has been modified rapidly. Hence, it is more cost-effective to make additional investment in high-speed switches instead of breakout cables and expensive QSA modules.

Conclusion

Both the QSFP+ breakout cables and QSA modules provide a smooth migration to the 40 Gigabit Ethernet. With these optics, you can reuse the existing 10G SFP+ cables, optical transceivers and switches when upgrading to 40G Ethernet. QSFP+ breakout cables is regarded as the cost-effective and reliable solutions for the most situations, but QSA module is preferable for the application with a single 10G connection.

Original source: QSA Module Vs. QSFP+ to SFP+ Breakout Cable – Chinacablebuy

Can I Use QSFP+ Optics on the QSFP28 Port?

100G Ethernet will have a larger share of network equipment market in 2017, according to Infonetics Research. But we can’t neglect the fact that 100G technology and relevant optics are still under development. Users who plan to layout 100G network for long-hual infrastructures usually met some problems. For example, currently, the qsfp28 optics on the market can only support up to 10 km (QSFP28 100GBASE-LR4) with WDM technology, which means you have to buy the extra expensive WDM devices. For applications beyond 10km, QSFP28 optical transceivers cannot reach it. Therefore, users have to use 40G QSFP+ optics on 100G switches. But here comes a problem, can I use the QSFP+ optics on the QSFP28 port of the 100G switch? If this is okay, can I use the QSFP28 modules on the QSFP+ port? This article discusses the feasibility of this solution and provides a foundational guidance of how to configure the 100G switches.

For Most Switches, QSFP+ Can Be Used on QSFP28 Port

As we all know that QSFP28 transceivers have the same form factor as the QSFP optical modules. The former has just 4 electrical lanes that can be used as a 4x10GbE, 4x25GbE, while the latter supports 40G ( 4x10G). So from all of this information, a QSFP28 module breaks out into either 4x25G or 4x10G lanes, which depends on the transceiver used. This is the same case with the SFP28 transceivers that accept SFP+ transceivers and run at the lower 10G speed.

QSFP+ can work on the QSFP28 ports

A 100G QSFP28 port can generally take either a QSFP+ or QSFP28 optics. If the QSFP28 optics support 25G lanes, then it can operate 4x25G breakout, 2x50G breakout or 1x100G (no breakout). The QSFP+ optic supports 10G lanes, so it can run 4x10GE or 1x40GE. If you use the QSFP transceivers in QSFP28 port, keep in mind that you have both single-mode and multimode (SR/LR) optical transceivers and twinax/AOC options that are available.

In all Cases, QSFP28 Optics Cannot Be Used on QSFP+ Port

SFP+ can’t auto-negotiate to support SFP module, similarly QSFP28 modules can not be used on the QSFP port, either. There is the rule about mixing optical transceivers with different speed—it basically comes down to the optic and the port, vice versa. Both ends of the two modules have to match and form factor needs to match as well. Additionally, port speed needs to be equal or greater than the optic used.

How to Configure 100G Switch

For those who are not familiar with how to do the port configuration, you can have a look at the following part.

  • How do you change 100G QSFP ports to support QSFP+ 40GbE transceivers?

Configure the desired speed as 40G:
(config)# interface Ethernet1/1
(config-if-Et1/1)# speed forced 40gfull

  • How do you change 100G QSFP ports to support 4x10GbE mode using a QSFP+ transceiver?

Configure the desired speed as 10G:
(config)# interface Ethernet1/1 – 4
(config-if-Et1/1-4)# speed forced 10000full

  • How do you change 100G QSFP ports from 100GbE mode to 4x25G mode?

Configure the desired speed as 25G:
(config)# interface Ethernet1/1 – 4
(config-if-Et1/1-4)# speed forced 25gfull

  • How do you change 100G QSFP ports back to the default mode?

Configure the port to default mode:
(config)# interface Ethernet1/1-4
(config-if-Et1/1)# no speed

Note that if you have no experience in port configuration, it is advisable for you to consult your switch vendor in advance.

Conclusion

To sum up, QSFP+ modules can be used on the QSFP28 ports, but QSFP28 transceivers cannot transmit 100Gbps on the QSFP+ port. When using the QSFP optics on the QSFP28 port, don’t forget to configure your switch (follow the above instructions). To make sure the smooth network transmission, you need to ensure the connectors on both ends are the same and no manufacturer compatibility issue exists.

Original source : http://www.chinacablesbuy.com/can-use-qsfp-optics-qsfp28-port.html