The Cisco GLC-BX-U-20KM (GLC-BX-U-20KM - Cisco 1Gbps 1000Base-BXU Single-mode Fiber 1310nm TX/1490nm RX 20km SFP Transceiver Module) is a Transceiver component engineered for sustained enterprise-class workloads. This part addresses common procurement scenarios where exact-match replacement, capacity expansion, or new-build deployment is required. Technical specifications include wavelength of 1310 nm, range of 20 km. Common deployment scenarios include data-center ToR (top-of-rack) switching, server-to-storage NAS/SAN connectivity, 10/25/40/100 GbE backbone aggregation, and edge router replacement in branch-office deployments. Pro Disk Network maintains the GLC-BX-U-20KM in our enterprise inventory and verifies each unit against manufacturer datasheet specifications prior to listing. New stock ships factory-sealed where available; refurbished units are tested under load before dispatch and ship with a 90-day Pro Disk Network functional warranty. Same-day dispatch on in-stock orders placed before 3pm ET; free standard ground shipping on US orders over $150.
The GLC-BX-U-20KM is a Cisco transceiver component with wavelength 1310 nm, range 20 km. Pro Disk Network sells the GLC-BX-U-20KM for $114.36 with same-day US shipping and a 30-day return guarantee.
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Reviewed by:Pro Disk Network Engineering Team — . Specifications, compatibility, and pricing for the GLC-BX-U-20KM are shown on this page.
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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-20KM compatible with my switch?
Pro Disk Network validates every GLC-BX-U-20KM 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-20KM ship?
Pro Disk Network dispatches the GLC-BX-U-20KM same-day on orders confirmed before 3 pm ET. Multi-pallet projects requiring crating ship within 2 business days. International shipping (Canada, Mexico, EU, APAC) takes 3-7 business days via DHL Express or FedEx International Priority.
The GLC-BX-U-20KM 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.
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.
Branch / Edge — Smaller form-factor switches and routers for branch sites. SD-WAN-compatible or static-VPN-attached as the architecture dictates.
What is the GLC-BX-U-20KM?
The GLC-BX-U-20KM is a Cisco network interface module with wavelength 1310 nm and range 20 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-20KM
Pros
Same-day US shipping cuts deployment downtime
Cons
Not for hyperscale ZR coherent — different SKU family
Some vendors deprecate firmware on EOL part numbers
Mismatched optic+switch firmware can require manual override
Frequently Asked Questions about GLC-BX-U-20KM
Is the GLC-BX-U-20KM a genuine Cisco part?
Yes. Pro Disk Network sources every GLC-BX-U-20KM 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-20KM compatible with my switch?
Pro Disk Network validates every GLC-BX-U-20KM 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-20KM ship?
Pro Disk Network dispatches the GLC-BX-U-20KM same-day on orders confirmed before 3 pm ET. Multi-pallet projects requiring crating ship within 2 business days. International shipping (Canada, Mexico, EU, APAC) takes 3-7 business days via DHL Express or FedEx International Priority.
What is the warranty on the GLC-BX-U-20KM?
New GLC-BX-U-20KM 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-20KM?
Email sales@prodisknetwork.com with the quantity and target ship date for a quote within one business day.
GLC-BX-D120 — GLC-BX-D120 - Cisco 1Gbps 1000BASE-BX10-D Downstream Bidirectional Single Fiber with DOM SFP Transceiver Module — $111.42
Pro Disk Network Buyer’s Guide: Transceiver
Optic Coding, Vendor Lock-In, and Multi-Vendor Compatibility
If you are running a multi-vendor leaf-spine architecture (Arista leaves and Cisco spines, for example), order optics coded for each endpoint separately. Optics in DAC and AOC cables are factory-coded to each end and cannot be flashed in-field. Plan the coding split at design time and document it in your network drawings.
Bandwidth Sizing for Spine-Leaf, EVPN-VXLAN, and Hyperconverged Storage
Sizing network bandwidth for a leaf-spine fabric using the GLC-BX-U-20KM starts with the workload mix. For general-purpose virtualisation, plan 10G server-to-leaf, 25G or 40G leaf-to-spine; oversubscription up to 4:1 is acceptable. For hyperconverged storage (vSAN, Ceph, Storage Spaces Direct), plan 25G server-to-leaf at minimum, 100G leaf-to-spine, oversubscription 1.5:1 maximum. East-west traffic dominates in HCI clusters and starves on oversubscribed fabrics.