QDD-400G-LR4-S – 400G LR4 QSFP-DD – Duplex LC SMF – 10km Reach

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QDD-400G-LR4-S Description

QDD-400G-LR4-S is a Cisco 400G QSFP-DD LR4 optical transceiver for 400GE links over duplex single-mode fiber at distances up to 10 km.

This SKU fits QSFP-DD 400G ports where the design needs an LC duplex SMF link rather than MPO parallel fiber or short-reach multimode cabling. It should be separated from QDD-400G-FR4-S, QDD-400G-DR4-S, QDD-4X100G-LR-S, and SR optics because the connector plan, fiber topology, reach, and peer optic are different.

Before ordering, confirm the Cisco host platform, QSFP-DD port support, software release, duplex LC PC or UPC patching, G.652 SMF path, link budget, price, stock, warranty coverage, and shipping window. Layer23-Switch can help check QDD-400G-LR4-S compatibility and quote details before the line item is approved.

Quick Specs

Parameter

Specification

Product ID

QDD-400G-LR4-S

Brand

Cisco

Product family

Cisco 400G QSFP-DD modules

Product type

400G-LR4 QSFP-DD optical transceiver

Form factor

QSFP-DD

Ethernet rate

400 Gigabit Ethernet

Connector type

Duplex LC PC/UPC

Fiber type

Single-mode fiber

Fiber standard

G.652

Cable topology

Duplex SMF

Maximum reach

10 km

Nominal wavelengths

1270, 1290, 1310, and 1330 nm

Nominal data rate

425 Gbps

High-speed electrical interface

400GAUI-8/CEI-56G-VSR-PAM4

Maximum supported insertion loss

6.3 dB

Maximum power consumption

12 W

Module operating temperature

0 to 75 degrees C

Standard warranty

5 years

Application Scenarios

400GE data center links over duplex SMF

Use QDD-400G-LR4-S when the planned 400G path uses duplex single-mode fiber and the optical distance is within Cisco’s documented 10 km reach. This is the LC duplex LR4 choice, not an MPO parallel fiber module.

Long-reach QSFP-DD uplinks

This transceiver is useful when a Cisco QSFP-DD port needs a longer SMF link than QDD-400G-FR4-S can cover. Confirm the host device and software support before the order moves from price check to purchase approval.

Optic inventory separation

Keep QDD-400G-LR4-S separate from DR4, 4x100G LR, FR4, BiDi, and SR optics in spare pools. The part numbers look similar in procurement systems, but the connector type, fiber plant, and operating mode are not interchangeable.

Product Comparison

Parameter

QDD-400G-LR4-S

QDD-400G-FR4-S

QDD-4X100G-LR-S

QDD-400G-DR4-S

QDD-400G-SR4.2-BD

Product family

Cisco 400G QSFP-DD modules

Cisco 400G QSFP-DD modules

Cisco 400G QSFP-DD modules

Cisco 400G QSFP-DD modules

Cisco 400G QSFP-DD modules

Product type

400G-LR4 QSFP-DD transceiver

400G-FR4 QSFP-DD transceiver

4 x 100GBASE-LR1 QSFP-DD transceiver

400GBASE-DR4 QSFP-DD transceiver

400GBASE-SR4.2 QSFP-DD transceiver

Connector type

Duplex LC PC/UPC

Duplex LC PC/UPC

MPO-12 APC

MPO-12 APC

MPO-12 UPC

Fiber type

Single-mode fiber

Single-mode fiber

Single-mode fiber

Single-mode fiber

Multimode fiber

Cable topology

Duplex SMF

Duplex SMF

Parallel SMF

Parallel SMF

Parallel MMF

Native link reach

10 km

2 km

10 km

500 m

70 m OM3; 100 m OM4; 150 m OM5

Breakout capability

Native 400GE LR4 link

Native 400GE FR4 link

4 x 100GBASE-LR1 operation

4 x 100G breakout to DR, FR, or LR peer optics

Up to 4 x 100GE breakout

Nominal wavelength

1270, 1290, 1310, and 1330 nm

1270, 1290, 1310, and 1330 nm

1310 nm

1310 nm

850 and 908 nm

Nominal data rate

425 Gbps

425 Gbps

4 x 100GE

425 Gbps

425 Gbps

Maximum supported insertion loss

6.3 dB

4 dB

6.3 dB

3 dB

1.9 dB

Maximum power consumption

12 W

12 W

12 W

12 W

12 W

  • QDD-400G-LR4-S is the duplex LC single-mode option when the 400G path requires Cisco’s documented 10 km LR4 reach.
  • QDD-400G-FR4-S uses the same LC duplex cabling style but is the shorter 2 km FR4 choice, so the link budget should be checked before substitution.
  • QDD-4X100G-LR-S and QDD-400G-DR4-S use MPO-12 parallel SMF and belong in a different breakout or parallel-fiber design.
  • QDD-400G-SR4.2-BD is a multimode MPO option and should not replace an LR4 SMF line item without changing the fiber plant and far-end optics.

Selection Guide

1. Choose it for 10 km duplex SMF 400GE

Select QDD-400G-LR4-S when the BOM needs a Cisco QSFP-DD 400G transceiver over duplex single-mode fiber and the planned optical path stays within the 10 km LR4 reach.

2. Check FR4 before overbuying reach

If the same LC duplex SMF run is within 2 km, QDD-400G-FR4-S may match the physical requirement. Use LR4 when the extra reach and 6.3 dB insertion-loss budget are required.

3. Avoid mixing LR4 with breakout optics

Do not treat QDD-400G-LR4-S as a substitute for QDD-4X100G-LR-S or QDD-400G-DR4-S. Those parts use MPO-12 parallel SMF and different operating modes.

4. Confirm the host platform before release

Check the exact Cisco switch, router, line card, QSFP-DD port, and software release in Cisco compatibility documentation before requesting a final quote or reserving stock.

Ordering Checklist

Check Item

What to Confirm

Why It Matters

Exact Product ID

QDD-400G-LR4-S

Prevents substitution with FR4, DR4, 4x100G LR, SR, or LR8 optics

Host compatibility

Cisco platform, line card, QSFP-DD port, and software release

Confirms the optic is supported in the intended device

Fiber plant

Duplex single-mode fiber using LC PC or UPC patch cords

LR4 is not an MPO parallel-fiber optic

Optical reach

Up to 10 km over G.652 SMF

Keeps the planned path inside Cisco’s documented distance

Link budget

6.3 dB maximum supported insertion loss

Helps avoid approval of an SMF path that is too lossy

Remote 400G optic

Matching 400G LR4-compatible endpoint

Avoids a wavelength, reach, or connector mismatch

Procurement support

Price, stock status, warranty support, and shipping destination

Keeps the purchase aligned with the installation or maintenance window

Specifications

Parameter Specification Parameter Specification
Product ID QDD-400G-LR4-S Brand Cisco
Product family Cisco 400G QSFP-DD cable and transceiver modules Product type 400G-LR4 QSFP-DD optical transceiver
Form factor QSFP-DD Ordering description 400G QSFP-DD Transceiver, 400G-LR4, Duplex LC, 10km Duplex SMF
Supported Ethernet rate 400 Gigabit Ethernet Connector type Duplex LC PC/UPC
Fiber type Single-mode fiber Fiber standard G.652
Cable topology Duplex SMF Maximum reach 10 km
Pull tab color Blue Nominal data rate 425 Gbps
High-speed electrical interface 400GAUI-8/CEI-56G-VSR-PAM4 Wavelengths 1270, 1290, 1310, and 1330 nm
Signal structure Four CWDM grid optical wavelengths Average transmit power per lane -2.7 to +5.1 dBm
Average receive power per lane -9.0 to +5.1 dBm Maximum supported insertion loss 6.3 dB
Pre-FEC bit error ratio 2.4 x 10^-4 FEC location Host platform
Maximum power consumption 12 W Module dimensions with pull tab 8.5 x 18.4 x 78.3/93.3 mm
Maximum module weight 100 g Module operating temperature 0 to 75 degrees C
Storage temperature -40 to 85 degrees C Laser class Class 1
Compliance reference RoHS 6 Standard warranty 5 years

Get More Information

Need pricing, stock, or shipping details for the QDD-400G-LR4-S ? Layer23-Switch can help you check current availability, lead time, and delivery options for this. Send us the part number, quantity, and destination country via live chat or email sales@layer23-switch.com for a fast quotation.

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    Albert Cooper
    Posted on 30/03/2026
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    If you’re worried about genuine vs counterfeit, don’t be — this is the real thing.

    Dennis Allen
    Posted on 30/03/2026
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    Ran it through our standard deployment checklist — every item passed.

    Richard Simmons
    Posted on 21/02/2026
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    Asked about bulk pricing and got a fair quote within hours. Professional and responsive.

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