Cisco C3KX-NM-1G
Catalyst 3K-X 1G Network Module
Product Highlights
When your Cisco Catalyst 3750-X or 3560-X access-layer switch needs flexible Gigabit Ethernet uplinks to the distribution or core layer, the C3KX-NM-1G delivers exactly that — four independent 1G SFP ports in a single, compact network module.
The C3KX-NM-1G occupies the dedicated uplink expansion slot on compatible Catalyst 3750-X and 3560-X Series switches, providing four 1000Base-X SFP interfaces that support a wide range of Cisco SFP transceivers including 1000BASE-SX, 1000BASE-LX/LH, 1000BASE-ZX, 1000BASE-BX10, GLC-T copper SFPs, and CWDM/DWDM variants. This flexibility lets you tailor each port to the exact distance and media type your network requires — from short-reach multimode fiber within a building to long-haul single-mode links between campuses.
The module integrates fully with the host switch's forwarding ASIC, preserving all QoS, ACL, MACsec encryption, and Flexible NetFlow monitoring capabilities without performance compromise. It is hot-swappable, enabling field replacement or upgrades with minimal disruption. No additional IOS license is required — the module operates under the switch's existing IP Base or IP Services license. With an MTBF of over 5 million hours, the C3KX-NM-1G is a proven, reliable choice for enterprise campus, branch office, and data center access-layer deployments where Gigabit uplink connectivity is the right fit.
Note: The Cisco Catalyst WS-C3750X platform and the C3KX-NM-1G module have reached End-of-Life status. This product is available as a pre-owned or refurbished unit, ideal for maintaining and expanding existing 3750-X / 3560-X deployments.
Features & Benefits
Four Independent 1G SFP Uplink Ports
The C3KX-NM-1G provides four 1000Base-X SFP ports, each operating independently at Gigabit Ethernet speeds. This gives network engineers the flexibility to build redundant uplinks, multi-path topologies, or dedicated connections to different VLANs — all from a single module slot.
Broad SFP Transceiver Support
Compatible with a wide range of Cisco SFP transceivers — including GLC-SX-MM, GLC-LH-SM, GLC-ZX-SM, GLC-T, and CWDM/DWDM optics — the module adapts to virtually any fiber or copper uplink scenario. Choose the right optic for each link distance and media type without changing the module itself.
Hot-Swappable Module Design
The uplink module is hot-swappable, allowing installation or replacement without powering down the host switch. This minimizes network downtime during maintenance windows and simplifies field upgrades in production environments.
Full Platform Feature Integration
The C3KX-NM-1G integrates directly with the Catalyst 3750-X / 3560-X forwarding ASIC. All platform features — including hardware-based QoS, ACLs, MACsec encryption, and Flexible NetFlow — are fully supported on the module's uplink ports with no performance degradation.
Zero Additional Licensing
No extra IOS license is needed. The module operates under the host switch's existing IP Base or IP Services license, keeping operational costs predictable and eliminating licensing complexity.
Exceptional Reliability
With a Mean Time Between Failure (MTBF) of 5,083,574 hours, the C3KX-NM-1G is engineered for continuous, long-term operation. This level of reliability makes it well-suited for mission-critical access-layer deployments.
Deployment Scenarios
Enterprise Campus Access-to-Distribution Uplinks
Deploy the C3KX-NM-1G in Catalyst 3750-X access-layer switches to provide redundant 1G fiber uplinks to distribution-layer switches. Four SFP ports enable multi-path designs with rapid failover, ensuring high availability for end-user traffic across campus buildings.
Branch Office Fiber Connectivity
In branch offices where copper uplinks are impractical due to distance limitations, the C3KX-NM-1G enables long-reach fiber connections using 1000BASE-LX/LH or 1000BASE-ZX SFPs. This extends reliable Gigabit connectivity across building floors or between nearby structures.
Maintaining Existing 3750-X / 3560-X Deployments
For organizations running established Catalyst 3750-X or 3560-X switch stacks that are not yet scheduled for migration, the C3KX-NM-1G provides a cost-effective way to add or replace uplink modules. Extend the useful life of your current infrastructure without a full platform refresh.
General
Interfaces
Features
Physical
Reliability
Compatibility
Compatibility Notes
Compatible Switch Platforms
The C3KX-NM-1G is compatible with all Cisco Catalyst 3750-X and 3560-X Series switch models, including but not limited to:
- WS-C3750X-24T, WS-C3750X-48T (data models)
- WS-C3750X-24P, WS-C3750X-48P, WS-C3750X-48PF (PoE/PoE+ models)
- WS-C3750X-12S, WS-C3750X-24S (SFP models)
- WS-C3560X-24T, WS-C3560X-48T (data models)
- WS-C3560X-24P, WS-C3560X-48P, WS-C3560X-48PF (PoE/PoE+ models)
Supported SFP Transceivers
- GLC-SX-MM / GLC-SX-MMD (1000BASE-SX, multimode)
- GLC-LH-SM / GLC-LH-SMD (1000BASE-LX/LH, single-mode)
- GLC-ZX-SM / GLC-ZX-SMD (1000BASE-ZX, extended single-mode)
- GLC-T (1000BASE-T, copper RJ-45)
- GLC-BX-U / GLC-BX-D (1000BASE-BX10, BiDi single-fiber)
- CWDM and DWDM SFP variants
Notes
- The module occupies the single dedicated uplink expansion slot on the host switch.
- No additional IOS license is required; the module operates under the switch's existing IP Base or IP Services license.
- Firmware updates are delivered via the host switch IOS image — no separate module firmware is needed.
- The C3KX-NM-1G does not support 10G SFP+ transceivers. For 10G uplink capability, see the C3KX-NM-10G.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| C3KX-NM-10G | Catalyst 3K-X 10G Network Module | Provides 2x 10G SFP+ ports plus 2x 1G SFP ports (4 physical ports total) for higher-speed uplinks when 10G connectivity is required. |
| C3KX-NM-10GT | Catalyst 3K-X 10G-BaseT Network Module | Offers 2x 10GBASE-T copper ports for 10G uplinks over Cat6a cabling — ideal when fiber infrastructure is unavailable. |
| C3KX-SM-10G | Catalyst 3K-X 10G Service Module | Service module with 2x 10G SFP+ ports plus dedicated hardware for Flexible NetFlow monitoring and MACsec encryption offload. |
