GLC-ZX-SMD-BCC | Cisco Compatible 1GB Single-Mode ZR - 70km (1000BASE-ZX)

Q: Will this work in place of the Cisco GLC-ZX-SMD?
A: Yes. The GLC-ZX-SMD-BCC meets the same 1000BASE-ZX standard, operates at 1550nm over single-mode fibre with an SFP form factor, and provides plug-and-play compatibility with Cisco Gigabit Ethernet platforms that accept the GLC-ZX-SMD.

Q: Which Cisco platforms support this transceiver?
A: This transceiver works in any Cisco switch or router with SFP ports that support 1000BASE-ZX optics, including Catalyst, Nexus, and ISR series. Compatibility is determined by the SFP port specification, not specific model numbers. Verify your platform datasheet lists 1000BASE-ZX or GLC-ZX-SMD support.

Q: Why does Cisco recommend a 10 dB attenuator for short spans?
A: The GLC-ZX-SMD transmits 0 to 5 dBm and the receiver sensitivity is better than negative 24 dBm, yielding a 21 dB link budget designed for long reach. On spans with less than 8 dB total loss, the received signal can exceed the receiver's maximum input power and cause bit errors. A 10 dB attenuator at each receiver end prevents saturation.

Q: What fibre type and connector are required for 70 km reach?
A: You need duplex LC-terminated OS1 or OS2 single-mode fibre (9/125 µm core). Actual reach depends on cumulative loss: at 0.35 dB/km attenuation plus splice and connector losses, 70 km is achievable within the 21 dB budget. Higher quality fibre with lower loss can extend reach slightly; older or higher-loss fibre reduces it.

Q: Can I monitor link health in real time with this module?
A: Yes. The module supports SFF-8472 Digital Optical Monitoring. Your switch or NOS can poll the transceiver's I2C interface to read current transmit power, receive power, temperature, bias current, and supply voltage. These values help diagnose marginal links, dirty connectors, or ageing lasers before they cause outages.