This Cisco QSFP-40G-ESR4 delivers Networking Devices functionality in a form factor and electrical specification matched to Cisco UCS C-Series and B-Series blade chassis, plus Catalyst and Nexus switching platforms. The unit is built for 24/7 enterprise duty cycles and is verified against the OEM part-number registry before listing. Technical specifications include network speed of 40 GbE, wavelength of 850 nm, range of 300 m, features of QSFP. 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 sources the QSFP-40G-ESR4 through reputable distribution channels and applies a verification check against the OEM compatibility matrix before each unit is added to active inventory. Each unit ships from a US fulfillment hub (Hillsboro OR, Atlanta GA, or Phoenix AZ) with same-day dispatch on in-stock orders before 3pm ET. Net 30 / Net 60 terms available for qualified business, government, and education accounts. 30-day Pro Disk Network functional warranty included; free US ground shipping on orders over $150.
The QSFP-40G-ESR4 is a Cisco networking devices component with network speed 40 GbE, wavelength 850 nm, range 300 m. Pro Disk Network sells the QSFP-40G-ESR4 for $367.34 with same-day US shipping and a 30-day free return guarantee.
Reviewed By
Reviewed by:Pro Disk Network Engineering Team — . Specifications, compatibility, and pricing for the QSFP-40G-ESR4 verified against the manufacturer datasheet and our internal lab benchmarks.
Quick Answer: Is the QSFP-40G-ESR4 compatible with my switch?
Pro Disk Network validates every QSFP-40G-ESR4 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 QSFP-40G-ESR4 ship?
If in stock, the QSFP-40G-ESR4 ships same business day on US orders placed before 2 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 QSFP-40G-ESR4 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.
New, Bulk, or Refurbished — Choosing Your Tier
Pro Disk Network offers the QSFP-40G-ESR4 across three procurement tiers. Each tier is fully functional and warranted; the choice comes down to budget, warranty length, and whether the deployment is production-critical or capacity-expansion.
Tier
Discount vs OEM List
Warranty
Best For
New (Sealed OEM)
25–40%
Cisco manufacturer warranty (1–5 yr)
Production-critical first-tier
New (Bulk OEM)
50–65%
3-year Pro Disk Network warranty
New cluster builds, secondary tier
Refurbished
75–85%
12-month advance replacement
Capacity expansion, lab, dev/test, EOL refresh
Bulk & Volume Pricing for QSFP-40G-ESR4
Ships from our US warehouse — same-day US dispatch on orders placed before 2pm ET. Net 30 terms available for verified businesses, government and education.
Volume discounts on the QSFP-40G-ESR4 are automatic at checkout. Net 30 terms available for verified businesses, government, and education. Email sales@prodisknetwork.com for orders above 100 units.
Quantity
Discount
Unit Price
1
0%
$367.34
5+
4%
$352.65
10+
8%
$337.95
25+
13%
$319.59
50+
18%
$301.22
100+
23%
$282.85
What is the QSFP-40G-ESR4?
The QSFP-40G-ESR4 is a Cisco enterprise networking device with network speed 40 GbE and wavelength 850 nm, 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 QSFP-40G-ESR4
Pros
Lower cost than the OEM channel — same physical optic
RoHS, FCC, and CE compliance documentation available
SFP+/QSFP28 modules pre-coded for major vendor firmware
Cons
Refurbished switches may show minor rack-rail wear
Power supplies sold separately on certain SKUs
Long-haul ZR4/CFP4 modules subject to export-control screening
Frequently Asked Questions about QSFP-40G-ESR4
Is the QSFP-40G-ESR4 a genuine Cisco part?
Yes. Pro Disk Network sources every QSFP-40G-ESR4 as factory-original Cisco inventory verified against the manufacturer parts registry before listing. 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 12 months.
Is the QSFP-40G-ESR4 compatible with my switch?
Pro Disk Network validates every QSFP-40G-ESR4 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 QSFP-40G-ESR4 ship?
If in stock, the QSFP-40G-ESR4 ships same business day on US orders placed before 2 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 QSFP-40G-ESR4?
New QSFP-40G-ESR4 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 (12 months refurbished, 36 months new bulk). DOA replacement is free within 30 days of receipt.
Do you offer bulk pricing for the QSFP-40G-ESR4?
Yes. Pro Disk Network offers automatic volume discounts at 10, 25, 50, and 100+ unit tiers. Net 30 terms are available for verified businesses, government, and education buyers. Email sales@prodisknetwork.com with the quantity and target ship date for a quote within one business day.
Pro Disk Network Buyer’s Guide: Networking Devices
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 QSFP-40G-ESR4 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 QSFP-40G-ESR4 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 QSFP-40G-ESR4 and the connected NICs support jumbo frames — some older NICs cap at 9000-byte payloads even when jumbo-enabled.