Does Cisco C9300-NM-8X Light Up During POST?: Quick Insights into Cisco Device Diagnostics

The Cisco C9300-NM-8X is a network module used with Cisco Catalyst 9300 Series switches to provide additional 10-Gigabit SFP+ uplink ports. When troubleshooting or deploying these modules, an important question is whether the module’s LEDs or ports light up during POST (Power-On Self Test). Knowing this behavior is critical for on-site diagnostics and ensuring proper initialization.

Behavior During POST:

During the POST sequence, the Cisco Catalyst 9300 switch will recognize and initialize its installed network modules, including the C9300-NM-8X. However, the ports on the C9300-NM-8X module do not immediately light up, as the SFP+ ports require the following conditions for illumination:

1. The switch must successfully complete its POST sequence.
2. A compatible transceiver (SFP/SFP+) must be inserted into one or more ports.
3. There must be an active network connection/link on the port(s).

So, under normal operation, you won’t see the port LEDs of the C9300-NM-8X module light up just during the POST itself—unless the above link criteria are already met. After the POST is complete and SFP modules are recognized with active links, the corresponding LED indicators will light up to reflect link status and activity. This behavior aligns with standard data center design principles: status lights are reserved for indicating active, recognized connections to help with clear visual diagnostics and streamlined troubleshooting.

As a designer, I always recommend incorporating clear hardware and visual feedback into any room planner or rack layout. This helps IT staff and clients instantly recognize the state of network equipment within a well-organized networking closet or data distribution room.

Tips 1:

If you need to verify if your C9300-NM-8X is functioning post-boot, insert a known-good SFP+ module and connect it to an active network device—this will trigger the LED indicators, confirming module operation and link-up status.

FAQ

Q: Will the C9300-NM-8X's ports light up if no SFP modules are inserted during POST?

A: No, the LED indicators for the C9300-NM-8X ports only illuminate when valid SFP modules are inserted and an active link is established, not simply during the POST.

Q: How can I tell if the network module is recognized after POST?

A: You can use the switch CLI: use show inventory or show module to verify that the C9300-NM-8X is detected and operational.

Q: What do flashing or amber lights on the C9300-NM-8X indicate?

A: Flashing green or amber lights generally mean different statuses—amber often indicates a problem (like no link or failed POST), while blinking green shows activity. Refer to the Cisco LED guide for specific behavior.

Q: Do all Cisco Catalyst modules behave the same way during POST?

A: Most high-performance modules for the Catalyst 9300 series follow similar POST and LED behavior, but always check module-specific documentation for details.

Q: Should I design server rooms to allow clear visibility of network module LEDs?

A: Absolutely. Good layout and accessibility are key—ensure that your rack arrangements provide easy visual access to LED status indicators for efficient troubleshooting and management.