Router Hardware Management Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

PDF

Router Hardware Management Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

Partial breakout for 400G optics on Cisco 8010 Series routers

Updated: September 11, 2026

Want to summarize with AI?

Log in

Explains how the partial breakout feature for 400G optics enables flexible port combinations and maximizes hardware utilization on Cisco 8010 Series routers.

A partial breakout feature is a hardware capability that

  • allows a QSFP‑DD 4×100GE optic to provide four distinct 100GE electrical lanes

  • enables different configurations so that not all lanes must be active or used in a single front-panel port, and

  • allows unused lanes to be reallocated to other ports for greater flexibility and improved hardware utilization.

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

Partial breakout for 4×100GE QSFP‑DD optics

Release 26.3.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*)

This feature enables flexible port combinations and maximizes hardware usage on the Cisco 8011-32Y8L2H2FH router by allowing a 4x100GE optic to be used as a 1x100GE, 2x100GE, or 3x100GE so that unused SerDes (Serializer/Deserializer) lanes can be reallocated to other ports.

*This feature is supported only on the Cisco 8011-32Y8L2H2FH router.

Partial breakout for 4×100GE QSFP‑DD optics on Cisco 8010 Series routers

Starting with Cisco IOS XR Release 26.2.1, partial breakout for QSFP-DD 4x100GE optics provides port-level flexibility and improves hardware utilization on the Cisco 8011-32Y8L2H2FH router, which is equipped with H100 (Helium-100) physical layer (PHY) devices1.

1 Cisco’s high‑speed physical layer (PHY) device used on platforms such as Cisco 8011-32Y8L2H2FH router to enable 200G and 400G Ethernet interfaces

Benefits of partial breakout on the Cisco 8011-32Y8L2H2FH router

Partial breakout on the Cisco 8011-32Y8L2H2FH router:

  • Enables flexible port combinations on platforms using H100 PHYs.

  • Improves hardware utilization and bandwidth allocation.

  • Allows to use both partial breakout and individual 100GE ports on the same PHY.

Partial breakout supported QSFP-DD optics

The following QSFP-DD optics support partial breakout:

  • QDD-400G-DR4-S

  • QDD-4X100G-FR-S

  • QDD-4X100G-LR-S

Partial breakout examples for 400G optics

With partial breakout enabled, if you configure 1x100G, 2x100G, or 3x100G on a port, say, Port 0 or Port 3, then the remaining SerDes lanes can be left unused and reassinged to other ports on the same Helium H100 PHY.

Without partial breakout, all four SerDes lanes are consumed by a single port, which blocks neighboring ports even if bandwidth is available.

This table provides some partial breakout examples.

The following table provide examples of partial breakout configurations.

Table 2. Partial breakout – Helium 1 PHY

Port 0

Port 1

Port 2

4x100G

–

–

3x100G

100

–

2x100G

100G

100G

2x100G

40G

40G

1x100G

100G

100G

1x100G

40G

40G
Table 3. Partial breakout – Helium 2 PHY

Port 3

Port 4

Port 5

Port 6

Port 7

Port 8

Port 9

Port 10

Port 11

4x100G

–

–

–

–

–

–

–

–

3x100G

50G

50G

–

–

–

–

–

–

2x100G

50G

50G

50G

50G

–

–

–

–

2x100G

10G/25G

10G/25G

10G/25G

10G/25G

–

–

–

–

1x100G

50G

50G

50G

50G

50G

50G

–

–

1x100G

10G/25G

10G/25G

10G/25G

10G/25G

50G

50G

–

–

Here, 100G supports 40G or 100G speed; 50G supports 10G, 25G, or 50G speed. Ports with a dash ('–') indicate disabled ports based on user configuration.

Note

Ports on the same quadrant share the same speed. For example, if Port 1 on one quadrant is configured with 100G speed, then Port 2 on the same quadrant should have 100G as the speed.

Partial breakout lane allocation for QSFP-DD modules

In a typical deployment, partial breakout allows Port 0 to use only 2x100GE lanes from a 4x100GE QSFP-DD module, while remaining lanes are assigned to ports P1 and P2.

Example configuration for Port 0:

speed 200g
breakout 2x10

With this configuration, Port 0 operates using two 100GE lanes, freeing additional lanes for assignment to ports P1 and P2. This supports customized bandwidth allocation across ports in high-speed deployments.