DATA CENTER SERIES: FluxLight SFP-10G-T Transceiver Application

10GBASE-T Cisco 34180YC Cisco UCS C460

Cisco Nexus 34180YC to Cisco UCS C460

There are many ways of connecting a Top of Rack (ToR) leaf switch to subtending computer and storage servers in the same or adjacent equipment racks. Other application notes in this series have depicted,

  • The use of a 10GBASE-SR SFP+ installed in the TOR switch and a similar SFP+ installed in an appropriate Host Bus Adaptor (HBA) equipped server (see: SFP-10G-SR Application).
  • A 40GBASE-SR4 QSFP+ in the TOR connected by an MPO-to-4xDuplex-LC hydra cable to four 10GBASE-SR SFP+ modules equipped in servers HBAs (see: QSFP-40G-SR4 Application).

The above methods are both high-performance, low-latency and relatively low power methods of ToR-Server interconnection. Many rack-mounted computer and storage servers come equipped with dual 10GBASE-T, 10GbE RJ45 ports. Although both power and latency are considerably higher using these ports versus using optical Ethernet, as shown in the tables below the cost savings of going the copper route are considerable. However, some extremely latency sensitive applications such as High Frequency Trading (HFT) will suffer some additional delay which may not be desirable or acceptable.

Table 1 10GbE Optical Interconnect Cost

Component Unit Cost Quantity Extended Cost
SFP-10G-SR Optical Transceiver $14 4 $56
OM3 MMF Jumper Cable 2 meters $16 2 $32
Dual 10GbE Host Bust Adaptor $400 1 $400
TOTAL: $488


Table 2 10GbE Copper Interconnect Cost

Component Unit Cost Quantity Extended Cost
SFP-10G-T Copper Transceiver $149 2 $298
CAT7 Copper Jumper Cable 2 meters $12 2 $24
TOTAL: $322


To depict this application with real-world products, a ToR switch from Cisco’s Nexus 3000 series and a rack-mounted service from Cisco UCS line have been selected. The only other pieces required are FluxLight SFP-10G-T transceivers and a couple of CAT7 Ethernet patch cables.

TOR LEAF SWITCH: Cisco Nexus 34180YC

Cisco Nexus 34180YC | TOR LEAF SWITCH

The Nexus 3400 platform is part of the latest generation of the fixed Nexus®3000 Series Switches. The 3000 series is squarely targeted for ToR applications. All members are compact (single rack unit) fixed configuration products. Across this family of products essentially all available rates of optical ethernet are offer, from 1G to 400G.

The specific switch cited in this example is the Nexus 34180YC. This switch offers great flexibility in ports speeds, covering 10G, 25G, 40G and 100G rates. The 34180YC is programmable allowing the user to customers to tailor packet forwarding behavior to the needs of their applications. For example, high speed financial trading applications can be optimized for the lowest possible latency. This switch is stocked with 48 SFP+/SFP28 ports (10G/25G) and 6 QSFP+/QSFP28 (40G/100G) ports. The switch supports full line rate Layer 2/3 switching on all these ports, totaling 3.6 Terabits/sec and 1.4 Gigapackets/sec.

The 34180YC may be equipped with a wide range of optical transceiver interface types across the many rates mentioned above. The tables below include the compatible transceiver types for the two categories of ports in the switch.

Table 3 SFP+/SFP28 Optical Transceivers

SFP-10G-SR SFP+ SR, 300m/OM3, 400m/OM4, duplex LC
SFP-10G-LR SFP+ LR, 10km, SMF, duplex LC
SFP-10G-LRM SFP+ LRM, 220 OM1 MMF, duplex LC
SFP-10G-ER  SFP+ ER, 40km, SMF, duplex LC
SFP-10G-ZR SFP+ ZR, 80km, SMF, duplex LC
SFP-10G-T SFP+ T, 30m, CAT7, RJ45
SFP-10GBX-UD-PAIR SFP+ BX, 10km, SMF, simplex LC


SFP+ BX, 40km, SMF, simplex LC
SFP-25G-SR-S SFP28 SR, 70m/OM3, 100m/OM4, duplex LC
SFP-25G-LR -S SFP28 LR, 10km, SMF, duplex LC


Table 4 QSFP+/QSFP28 Optical Transceivers

QSFP-40G-SR4 QSFP+ 40G SR4, 100m, OM3 MMF, MPO connector
QSFP-40G-CSR4 QSFP+ 40G CSR4, 300m OM3 MMF, MPO connector
WSP-Q40GLR4L QSFP+ 40G LR4L, 2Km SMF, duplex LC
QSFP-40G-ER4 QSFP+ 40G ER4, 40Km SMF, duplex LC
QSFP-40G-SR-BD QSFP+ 40G Bidirectional MMF, 100m OM3, duplex LC
QSFP-4X10G-LR-S QSFP+ 40G, 10km, SMF, MPO connector
QSFP-40G-LR4 QSFP+ 40G LR4, 10km SMF, duplex LC
QSFP-100G-SR4-S QSFP28 100G SR4, 100m, OM3 MMF, MPO connector
QSFP-100G-CWDM4-S QSFP28 100G PSM4, 500m SMF, MPO connector
QSFP-100G-PSM4-S QSFP28 100G PSM4, 2Km SMF, duplex LC
QSFP-100G-ER4L-S QSFP28 100G ER4, 40Km SMF, duplex LC
QSFP-100G-LR4-S QSFP28 100G LR4, 10km SMF, duplex LC



Rack-mounted Server: Cisco UCS C460 M4 Rack Server

Rack-mounted Server: Cisco UCS C460 M4 Rack Server
Cisco UCS C460 M4 Front View
Rack-mounted Server: Cisco UCS C460 M4 Rack Server
Cisco UCS C460 M4 Rear View

Cisco’s C460 M4 server is a member of the Unified Computing Servers family. The basic unit is 4 rack units in height (4RU, approximately 7”) and is based on the Intel Xeon E7-4800 andE7-8800 family of processors. Each server may be equipped with up to 12 SFF drives (SSD, SAS or SATA) and up to 6 Terabytes of DDR3 or DDR4 memory in its 96 DIMM slots. It includes two 10GbE copper ports without the need for a Host Bus Adaptor. These servers offer ten PCIe Gen 3 slots and are designed for high availability with redundant power suppliers.


FluxLight SFP-10G-T Cisco

FluxLight’s SFP-10G-T (click link for datasheet) is a Cisco® compatible 10GBase-T SFP+ Optical Transceiver and is factory pre-programmed with all the necessary configuration data for fully compatible operation with all Cisco equipment offering SFP+ slots. The FluxLight SFP-10G-T includes an RJ45 8-wire connector and supports the follow link lengths at various speeds and classes of Ethernet cable.

  • 10GBase-T links up to 30m using Cat 7 Cable
  • 5GBase-T links up to 50m on Cat5e or better
  • 5GBase-T up to 75m on Cat5e or better
  • 10/100/1000Base-T on Cat5e or better

Although Cisco does not offer a 10GBASE-T SFP+ transceiver, this devices performs identically to Cisco® original transceivers, are 100% compatible and support full hot swappable operation. The SFP-10G-T is 100% MSA (Multi-Source Agreement) compliant, see: SFP+ MSA,


FluxLight FL-CAT7-10FT

To connect the SFP-10G-Ts in the Cisco Nexus 34180YC to the built-in 10GBase-T ports in the UCS C460 M4 servers, it is highly recommended to use a CAT7 Ethernet cable to reliably achieve full-duplex transmission at 10Gbps. 

Putting it all together

The Cisco Nexus 34180YC switch occupies 1RU and is typically placed at the top of the rack. Each UCS C460 M4 occupies 4RU. In this example two 10Gbps links are used per server, therefore, two FluxLight 10GBASE-T modules must be installed in the 34180YC for each server. So, in the depiction below, a total of 4 FluxLight SFP-10G-T modules are used.

10GBASE-T Cisco 34180YC Cisco UCS C460 Diagram-01

The SFP-10G-T modules are inserted into 4 of the 48 the SFP+/SFP28 slots in the 34180YC. CAT7 Ethernet jumpers are used to connect each of these SFP modules to the built-in 10GbE RJ45 ports in the servers. Typically, the two cables between each server and the ToR switch are diversely routed (opposite sides of the rack) so that if one is accidentally removed it does not completely isolation that server.

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