QSFP+ Direct Attach Copper Cables for EX Series Switches

Quad small form-factor pluggable plus (QSFP+) direct attach copper (DAC) cables are suitable for in-rack connections between QSFP+ ports of EX Series switches. They are suitable for short distances of up to 10 meters, making them ideal for highly cost-effective networking connectivity within a rack and between adjacent racks. This article will introduce EX Series switches and QSFP+ DAC for EX Series switches.

Introduction to EX Series Switches

EX Series switches deliver scalable port densities and carrier-proven high availability features that consolidate legacy switch layers, helping to reduce capital and operational expenses and advance the economics of networking. For example, the EX 4200 series Ethernet switches with Virtual-Chassis technology, deliver the same Gigabit Ethernet (GbE) and 10GbE port densities as traditional chassis-based switches, but at one-eighth the footprint and less than one third the cost. The EX Series switches are right-sized for campus, data center and remote office environments and feature many of the same carrier-class hardware and software architectures found in core routers that were purpose-built to support the convergence of data, voice, and video onto a single always-on network.

By alleviating the cost, complexity and risk associated with legacy switch infrastructures, the EX Series switches enable high-performance businesses to deploy a high-performance network infrastructure based on three key tenets – operational simplicity, carrier-class reliability, and integration and consolidation – to enable ubiquitous access to strategic assets, reduce network downtime and enhance overall security to shared assets across the extended enterprise.

Cable Specifications of QSFP+ DAC

QSFP+ direct attach copper (DAC) cable is hot-removable and hot-insertable. QSFP+ DAC mainly has two kinds. One is a cable that connects directly into two QSFP+ modules, one at each end of the cable. The cables use integrated duplex serial data links for bidirectional communication and are designed for data rates up to 40 Gbps. The other is a breakout cable consisting of a QSFP+ transceiver on one end and four SFP+ transceivers on the other end. The QSFP+ transceiver connects directly into the QSFP+ access port on the QFX Series device. The cables use high-performance integrated duplex serial data links for bidirectional communication on four links simultaneously. The SFP+ links are designed for data rates up to 10 Gbps each.

The following table describes the software support for QSFP+ passive DAC cable lengths on EX Series switches for Junos OS releases.

SWITCH	SOFTWARE SUPPORT ADDED	DAC MODEL NUMBER
EX44300 switches	Junos OS for EX Series switches, Release 13.2X51-D15 or later	EX-QSFP-40GE-DAC-50CM QFX-QSFP-DAC-1M QFX-QSFP-DAC-3M JNP-QSFP-DAC-5M
EX4300 switches	EX4300-24T, EX4300-24P, EX4300-48T, EX4300-48T-AFI, EX4300-48P, EX4300-48T-DC, and EX4300-48T-DC-AF switches—Junos OS for EX Series switches, Release 13.2X50-D10 or later EX4300-32F switches—Junos OS for EX Series switches, Release 13.2X51-D15 or later EX4300-24T-S, EX4300-24P-S, EX4300-32F-S, EX4300-48T-S, and EX4300-48P-S switches—Junos OS for EX Series switches, Release 13.2X51-D26 or later	EX-QSFP-40GE-DAC-50CM QFX-QSFP-DAC-1M QFX-QSFP-DAC-3M JNP-QSFP-DAC-5M
EX4550 switches	EX4550-32T-AFI, EX4550-32T-AFO, EX4550-32T-DC-AFI, EX4550-32T-DC-AFO, EX4550-32F-AFI, EX4550-32F-AFO, EX4550-32F-DC-AFI, and EX4550-32F-DC-AFO switches—Junos OS for EX Series switches, Release 13.2X50-D10 or later EX4550-32F-S switches—Junos OS for EX Series switches, Release 12.3R5 or later	EX-QSFP-40GE-DAC-50CM QFX-QSFP-DAC-1M QFX-QSFP-DAC-3M JNP-QSFP-DAC-5M

Conclusion

QSFP+ direct attach copper cables can provide cost-effective and reliable 40G speed connections for EX Series switches with distances reaching up to 10 meters. As the leading fiber optical manufacturer in China, FS.COM offers a wide selection of QSFP+ DAC with low cost but high performance. In addition, 10G SFP+ to SFP+ DAC (eg. HP JD096C), 25G SFP28 to SFP28 DAC, 40G QSFP+ to 4 XFP DAC, 100G QSFP28 to QSFP28 DAC, 100G QSFP28 to 4 SFP28 DAC are also available for your choice. All these DACs are with 100% compatibility and can be customized according to your special requirements.

QSFP+ Transceiver, AOC, DAC – Which Is You Choice?

The IEEE 802.3ba committee ratified the 40 Gigabit Ethernet standard and along with the general specification, defined a number of fiber optic interfaces. For 40GbE direct cabling between two devices using QSFP+ port, there are several options including QSFP+ transceiver option, QSFP+ DAC (Direct Attach Copper) cable, and QSFP+ AOC (Active Optical Cable). Among these options, each of them has its own merits. This article will compare them and point out which is more cost-effective for your networks.

QSFP+ Transceiver

The 40-Gigabit QSFP+ transceiver module is a hot-swappable, parallel fiber-optical module with four independent optical transmit and receive channels. These channels can terminate in another 40-Gigabit QSFP+ transceiver, or the channels can be broken out to four separate 10-Gigabit SFP+ transceivers. The QSFP+ transceiver module connects the electrical circuitry of the system with either a copper or an optical external network. The transceiver is used primarily in short reach applications in switches, routers, and data center equipment where it provides higher density than SFP+ modules.

Cables for 40 Gigabit Ethernet

Copper Cables: QSFP + to QSFP + copper cable and QSFP + to 4SFP + breakout copper cable are the two common types of QSFP + cables. QSFP + to QSFP + copper cables are hot-removable and hot-insertable. A cable consists of a cable assembly that connects directly into two QSFP + modules, one at each end of the cable. QSFP + to 4 SFP + breakout copper cable is with one QSFP + on one end and four SFP + on the other end. It allows a 40G Ethernet port to be used as four independent 10G ports thus providing increased density while permitting backward compatibility and a phased upgrade of equipment.

Fiber Cables: Active optical cable (AOC) assemblies were invented to replace copper technology in data centers and high performance computing (HPC) applications. The 40G QSFP + AOC is a parallel 40Gbps quad small form factor pluggable (QSFP +) active optical cable, which supplies higher port density and total system cost. The QSFP + optical modules provide four full-duplex independent transmit and receive channels, each are able of 10Gbps operation 40Gbps aggregate bandwidth of at least 100m multimode fiber.

Which to Choose?

Case 1: Distances Below 5 m
If the transmission distances is under 5 m, like the case that two switch ports are connected within the same rack or between racks located within the same room. The QSFP+ passive DAC cable is recommended. Take the Cisco compatible QSFP+ optics for example:

DAC	5m Cisco QSFP-H40G-CU5M Compatible 40G QSFP+ Passive Direct Attach Copper Cable	US$ 65.00
AOC	5m Cisco QSFP-H40G-AOC5M Compatible 40G QSFP+ Active Optical Cable	US$ 140.00
Transceiver & Cable	Cisco QSFP-40G-SR4 Compatible 40GBASE-SR4 QSFP+ 850nm 150m DOM Transceiver	US$ 85.00
	5M OM4 12-fiber MTP Fiber Optic Trunk Cable for 40GBASE-SR4	US$ 73.00

Case 2: Distances Below 100 m (< 5 m)
For the case that transmission distance is below 100 m but beyond 5 m, the QSFP+ AOC is an ideal choice for use. In this case, the QSFP+ passive DAC cable cannot achieve such long reach requirement because of its performance limitation. While the 40GBASE-SR4 QSFP+ transceiver can do this but the cost of the MTP trunk cable is higher. Thus, here, the QSFP+ AOC is preferred.

Case 3: Distances Above 100 m
If the transmission distance is longer than 100 m, DAC cables and AOCs are usually not recommended. In this case, the 40G QSFP+ modules which are used for short-reach applications are recommended.

40G QSFP+ cables can provide inexpensive and reliable 40G speed connections using either copper cables with distances reaching up to 30ft (10 meters length) or active optical cables reaching even 300ft (100 meters). Of course, all the above are just rough estimates of the optics. In reality, more details should be included according to your specific requirements.

QSFP+ Optics for High-Density 40GE Connectivity

With the development of the SFF-8436 Multi Source Agreement, many vendor are now offering a variety of IEEE- and MSA-compliant Quad Small Form-Factor Pluggable Plus (QSFP+) devices for fiber networks. And there are basic three 40G QSFP+ optics for this standard: 40G LR4 QSFP+ transceiver, 40G SR4 QSFP+ transceiver and 40G LR4 parallel single mode (PSM) transceiver. This article will take a close look at these 40G QSFP+ optics for high-density 40 GE connectivity.

40G LR4 QSFP+ Transceiver

Conforming to the 802.3ba (40GBASE-LR4) standard, the 40G LR4 QSFP+ transceiver together with the LC connector can support an optical link length up to 10 kilometers over single mode fiber. For example, the following Juniper JNP-QSFP-40G-LR4 compatible 40GBASE-LR4 QSFP+ transceiver offers 4 independent transmit and receive channels, supporting link distance of 10 km over single mode fiber. In the process of transmitting, this kind of transceiver has to introduce MUX/DEMUX to multiplex/de-multiplex optical signals.

The working principle of this kind of QSFP+ transceiver is : in the transmit side, four 10 Gbp/s serial data streams are passed to laser drivers. The laser drivers control directly modulated lasers (DMLs) with wavelengths. the output of the four DMLs are optically multiplexed to a single-mode fiber through an industry-standard LC connector. In the receive side, the four 10 Gbp/s optical data streams are optically de-multiplexed by the integrated optical demultiplexer; then, each data steam is recovered by a PIN photodetector/transimpedance amplifier and passed to an output driver.

40G SR4 QSFP+ Transceiver

The 40G SR4 QSFP+ transceiver, conforming to the 802.3ba (40GBASE-SR4) standard, provides a 40G optical connection using MPO/MTP fiber ribbon connectors. Unlike the 40G LR4 QSFP+ transceiver, this kind of transceiver are used together with multi-mode fiber, supporting with a link length up to 100 meters on OM3 cable and 150 meters on OM4 cable.

The operating principle of the 40G SR4 QSFP+ Transceiver is : the transmitter convertsparallel electrical input signals into parallel optical signals through the use of a laser array. Then the parallel optical signals are transmitted parallelly through the multi-mode fiber ribbon. Reversely, the receiver converts parallel optical input signals via a photo detector array into parallel electrical output signals.

40G LR4 Parallel Single Mode (PSM) Transceiver

40G PSM transceivers are used to provide support for up to four 10Gb Ethernet connections on a QSFP+ port over single mode fiber. These transceivers support distance of up to 10 kilometers over single mode fiber using an 8 parallel fiber MPO interface. Each fiber pair can be broken out to a 10Gb Ethernet connection, compatible with up to four 10GBASE-LR interfaces. The MPO to 4 x LC single mode fiber patch cord can be used to breakout the 4 fiber pair of the MPO parallel connector to 4 separate fiber pairs.

Summary

To sum up, 40G SR4 QSFP+ transceivers are suitable for short-distance transmissions. So they are often used in data centers to interconnect two Ethernet switches with 12 lane ribbon OM3/OM4 cables. while 40G LR4 QSFP+ transceivers and 40G LR4 PSM transceivers are often used in long-distance transmission applications. Fiberstore offers a wide range of 40G QSFP+ transceivers, like 40GBASE-SR4, 40GBASE-LR4, 40GBASE-CR4 QSFP+ transceivers, etc. Besides, we also provide 40G direct attach cables, such as Juniper QFX-QSFP-DAC-1M, Cisco QSFP-4X10G-AOC3M and so on.

Reference:http://www.fiber-optic-transceiver-module.com/basic-40g-qsfp-optics-for-40g-transmission.html