This Cisco GLC-BX-U-40KM delivers Transceiver functionality and is built for 24/7 enterprise duty cycles. Technical specifications include range of 40 km. Workload fit covers VMware NSX overlay networking, Kubernetes pod-to-pod east-west bandwidth, Storage Replica replication, and high-throughput backup network paths between ToR switches and backup targets. Pro Disk Network supplies the GLC-BX-U-40KM to US business buyers. Stocked units ship same-day on in-stock orders placed before 3pm ET. Pro Disk Network applies a 90-day functional warranty. Free US ground shipping on orders over $150; same-day expedited (UPS Next Day Air, FedEx Priority) available at checkout.
The GLC-BX-U-40KM is a Cisco transceiver component with range 40 km. Pro Disk Network sells the GLC-BX-U-40KM for $145.87 with same-day US shipping and a 30-day return guarantee.
Reviewed By
Reviewed by:Pro Disk Network Engineering Team — . Specifications, compatibility, and pricing for the GLC-BX-U-40KM are shown on this page.
Trust Signals
US-based LLC — 7345 W Sand Lake Rd, STE 210, Office 3208, Orlando, FL 32819
Same-Day US Shipping — orders before 3pm ET ship today via UPS
30-Day Returns — pre-paid label on DOA and defective items
Quick Answer: Is the GLC-BX-U-40KM compatible with my switch?
Pro Disk Network validates every GLC-BX-U-40KM against the target switch's published compatibility matrix before shipment. If you let us know your switch model and firmware version, we will confirm fitment and code the module appropriately (Cisco-coded, Juniper-coded, HPE-coded, etc.) at no extra charge.
How fast does the GLC-BX-U-40KM ship?
If in stock, the GLC-BX-U-40KM ships same business day on US orders placed before 3 pm ET. Most US ZIP codes receive next-business-day or 2-day delivery via FedEx/UPS Ground or Express. Bulk and project orders shipping in pallets are typically dispatched within 24-48 hours.
The GLC-BX-U-40KM is deployed by US enterprises, MSPs, government, and education customers across multiple infrastructure scenarios. Below are the most common deployment patterns Pro Disk Network sees in real-world orders.
Spine-Leaf Fabric — Top-of-rack 25G/100G aggregation between leaf and spine switches. Match speed and form factor across both endpoints.
Server Uplink — 10G/25G server-to-leaf uplink — pair with matching DAC or AOC at the host NIC to avoid optic mismatch.
DCI (Data Center Interconnect) — Inter-DC routing or aggregation. LR4/LR8 transceivers for 10–80 km, ER4 for 40 km, ZR4 for coherent long-haul.
Campus Distribution — Catalyst-class campus distribution between IDF and MDF closets. PoE+ where wireless APs and IP phones share infrastructure.
What is the GLC-BX-U-40KM?
The GLC-BX-U-40KM is a Cisco network interface module with range 40 km, manufactured by Cisco. Pro Disk Network ships this part new and certified-refurbished from our US warehouse with same-day dispatch on orders placed before 3 PM ET, backed by a 30-day return guarantee.
Pros & Cons of GLC-BX-U-40KM
Pros
Matched-pair option for redundant link orders
Cabling and DAC/AOC labels clearly mark optic class
Cons
Third-party optic — some firmware revs require "service unsupported transceiver-type"
Bulk DAC orders may ship LTL on >100-pc reels
Confirm transceiver coding before mixing vendors in the same chassis
Frequently Asked Questions about GLC-BX-U-40KM
Is the GLC-BX-U-40KM a genuine Cisco part?
Yes. Pro Disk Network sources every GLC-BX-U-40KM as factory-original Cisco inventory. New units arrive sealed in OEM packaging; refurbished units are pulled from decommissioned Cisco servers, surface-tested, and re-warranted by Pro Disk Network for 90 days.
Is the GLC-BX-U-40KM compatible with my switch?
Pro Disk Network validates every GLC-BX-U-40KM against the target switch's published compatibility matrix before shipment. If you let us know your switch model and firmware version, we will confirm fitment and code the module appropriately (Cisco-coded, Juniper-coded, HPE-coded, etc.) at no extra charge.
How fast does the GLC-BX-U-40KM ship?
If in stock, the GLC-BX-U-40KM ships same business day on US orders placed before 3 pm ET. Most US ZIP codes receive next-business-day or 2-day delivery via FedEx/UPS Ground or Express. Bulk and project orders shipping in pallets are typically dispatched within 24-48 hours.
What is the warranty on the GLC-BX-U-40KM?
New GLC-BX-U-40KM units carry the full Cisco manufacturer warranty (typically 1 to 5 years depending on product line). Refurbished and bulk-OEM units include a Pro Disk Network advance-replacement warranty (90 days refurbished). DOA replacement is free within 30 days of receipt.
Do you offer bulk pricing for the GLC-BX-U-40KM?
Email sales@prodisknetwork.com with the quantity and target ship date for a quote within one business day.
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Pro Disk Network Buyer’s Guide: Transceiver
Optic Coding, Vendor Lock-In, and Multi-Vendor Compatibility
Networking optics — SFP, SFP+, QSFP+, QSFP28 — are physically interoperable across vendors but logically restricted by firmware coding. The GLC-BX-U-40KM is coded for a specific vendor family at our factory step before shipping, which preserves the OEM warranty workflow and allows the optic to be recognised without ‘service unsupported-transceiver’ CLI overrides. Mixing third-party optics with same-vendor optics in the same chassis is safe; mixing across vendor codings sometimes triggers warnings in the switch log.
Bandwidth Sizing for Spine-Leaf, EVPN-VXLAN, and Hyperconverged Storage
For EVPN-VXLAN overlays, the GLC-BX-U-40KM carries the underlay tunnels in addition to the workload traffic. Plan for VXLAN encapsulation overhead (50 bytes) plus MTU headroom; set the underlay MTU to 9216 (jumbo frames) and the overlay MTU to 9000. Make sure both the GLC-BX-U-40KM and the connected NICs support jumbo frames — some older NICs cap at 9000-byte payloads even when jumbo-enabled.