While most new fiber interconnects have moved to 10Gbps and higher rates, good old 1Gbps connections are all that is required in many instances. In many cases, a large number of low utilization 10/100/1000 Ethernet ports can be aggregated into a few 1Gbps links using low-cost 1GbE transceivers.
This application note describes the use of 1000BASE-SX links between small edge/access switches and a larger core/spine switch.
CORE SWITCH: Cisco Nexus 9372PX
The Nexus® 9372PX platform is part of the latest generation of the fixed Nexus® 9000 Series Switches. Cisco uses the phrase “Application Centric Infrastructure (ACI)” to describe the technology on which this series is based. The primary elements of ACI are,
- Automated IT workflows to shorten app deployment
- Software Defined Networking (SDN)
- Advanced security and analytics
- Seamless application migration across multiple locations
The Cisco Nexus 9372PX Switch is a 1RU switch that supports 1.44 Tbps of bandwidth and over 1.15 mpps (million packets per second). The switch includes 48 SFP+ slots which may be equipped with either SFP or SFP+ modules so both 1G and 10G speeds are possible on a per port basis. Six fixed QSFP+ uplink slots are included in the N9372PX.
The N9272PX 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 1 SFP Optical Transceivers
| GLC-SX-MM, GLC-SX-MMD | SFP SX, 550m/OM2, MMF, duplex LC |
| GLC-LH-SM, GLC-LH-SMD | SFP LX, 10km, SMF, duplex LC |
| GLC-EX-SMD | SFP EX, 40km, SMF, duplex LC |
| GLC-ZX-SMD | SFP ZX, 70km, SMF, duplex LC |
| GLC-TE | SFP T, 100m, CAT5e, RJ45 |
| GLC-BX-U, GLC-BX-D | SFP BX, 10km/40km/80km, SMF, simplex LC |
Table 2 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-10GBX-U-40, SFP-10GBX-D-40 | SFP+ BX, 40km, SMF, simplex LC |
Table 3 QSFP+ 40G 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-40G-LR4 | QSFP+ 40G LR4, 10km SMF, duplex LC |
ACCESS SWITCH: Cisco Catalyst 9200
Cisco’s Catalyst 9200 series is available in both fixed and modular configurations. The SKUs of the eight fixed models start with C9200L- and the four modular uplink models with C9200-. All models include either 24 or 48 RJ45 10/100/1000 copper downlink ports. If the SKU has a “P” after the 24 or 48 port number, the ports support Power Over Ethernet (POE). All eight fixed models offer 4 pluggable optical uplinks, either SFP or SFP+. If the final letter in the SKU is a “G” it means the switch has 1Gbps uplinks and if it ends in “X” it means 10Gpbs. In this example the C9200L-24G is selected as we only require 1GbE uplinks. The table below lists compatible transceivers that may be used with this switch.
Table 4 SFP Optical Transceivers
| GLC-SX-MM, GLC-SX-MMD | SFP SX, 550m/OM2, MMF, duplex LC |
| GLC-LH-SM, GLC-LH-SMD | SFP LX, 10km, SMF, duplex LC |
| GLC-EX-SMD | SFP EX, 40km, SMF, duplex LC |
| GLC-ZX-SMD | SFP ZX, 70km, SMF, duplex LC |
| GLC-TE | SFP T, 100m, CAT5e, RJ45 |
| GLC-BX-U, GLC-BX-D | SFP BX, 10km/40km/80km, SMF, simplex LC |
1000BASE-SX OPTICAL TRANSCEIVERS: FluxLight GLC-SX-MM
FluxLight’s GLC-SX-MM (click link for datasheet) is a Cisco® compatible 1000Base-SX 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 GLC-SX-MM includes a dual-LC connector and supports the follow link lengths over compatible multimode fiber jumpers,
- FDDI-grade, 160 MHz*Km, 62.5 micron: 220m
- OM1, 200 MHz*Km, 62.4 micron: 275M
- OM2, 500 MHz*Km, 50 micron: 550m
- OM3, 2000 MHz*Km, 50 micron: 1000m
FluxLight’s device performs identically to Cisco® original transceivers, are 100% compatible and support full hot swappable operation. The GLC-SX-MM is 100% MSA (Multi-Source Agreement) compliant, see: SFP MSA,
OM1 MULTIMODE FIBER JUMPER CABLE: FluxLight PN: FL-LCLC-DXMM-2M
To connect the GLC-SX-MM modules in the Cisco Nexus 9372PX to the same type of modules equipped in the C9200 switches, a duplex multimode fiber jumper with dual-LC connectors at each end is used. The one shown here is an OM1 fiber type that will support link up to 220 meters. If longer reaches are required, FluxLight has OM3 versions, see: FluxLight OM3 LC-LC jumpers.
Putting it all together
To create a robust network, each C9200 access switch is dual-homed to two Nexus 9372PX switches. Two FluxLight GLC-SX-MM modules are equipped in the C9200 switches as shown in the diagram below. Since there are three C9200 switches in the example, a total of three GLC-SX-MM modules must be equipped in each of the N9372 switches.
Cisco switches were used to demonstrate the application. FluxLight carries 1000BASE-SX modules compatible with a wide range of OEM switches. Some popular models are listed below.
Table 1 SFP Optical Transceivers for Popular Switch OEMs
| EX-SFP-1GE-SX | Juniper |
| J4858C | HPE |
| MA-SFP-1GB-SX | Meraki |
| 10051 | Extreme Networks |