Configuration Guide for Cisco NCS 1014, IOS XR Releases 26.x.x

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Configuration Guide for Cisco NCS 1014, IOS XR Releases 26.x.x

Application select code provisioning

Updated: August 25, 2026

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This section explains the purpose, structure, and operational context of application select codes (AppSel codes) for QDD optical modules.

Application select code, also known as AppSel code, is a feature that:

  • allows the host device to choose the operating mode of a QDD module

  • allows you to configure the media code, and

  • specifies how to configure the optical side of a module.

Common Management Interface Specification

The Common Management Interface Specification (CMIS) specifications set rules for how QDD modules work and how a host device sets them up. CMIS provides a consistent way for host devices, such as routers or switches, to communicate with and control optical modules, regardless of the module manufacturer.

Understanding AppSel codes and module operation modes

Each QDD module can operate in different modes, identified by a unique AppSel code. This code acts like a unique ID for each mode. Each mode has an application descriptor, which explains how the module handles data. It describes how signals are processed between the connections on the host side and the optical side.

The optical side is also known as the media side of the module. The AppSel code includes a media code, which tells the module how to set up its optical side. The host software uses this media code to control the module’s optical interface. The host software also sets up other components, like the physical layer (PHY), SerDes, and MacPort, to complete the data path.

AppSel code storage and compatibility

Modules store a list of the AppSel codes they support in their EEPROM memory. This helps the host system or device know which settings the module can use. Some codes, like 400G-OIF-ZR and 400G-OpenZR+, are standard and follow industry rules. Other codes are custom, created by third-party vendors to provide users with more options on a single module. These custom codes may cause compatibility problems; for instance, Cisco routers may not function properly with modules using unrecognized custom codes.

Application mode selection

This feature allows users to select from all application modes advertised by the optical module. You can choose all application modes a module supports.

AppSel operation mode parameters

AppSel supports operation modes based on these parameters:

  • Data rate, such as 100GE or 400GE

  • Signal type

  • Signal processing between host side and media side

  • Optical configuration, based on the media code, which is part of the AppSel code.

Supported card and pluggables

In Release 25.3.1, AppSel is supported on the DP04QSDD-ULH-A1 pluggable connected to the QXP-K9 card.

Benefits of AppSel code provisioning

This section explains the benefits of provisioning AppSel code for flexible and efficient configuration of optical modules.

These are the benefits of provisioning AppSel code:

  • Enables you to choose any application mode supported by the optical module for greater flexibility.

  • Enables direct configuration of the NPU, PHY, and optics to match the selected application’s datapath.

  • Removes the need for Cisco IOS XR software to implement new proprietary modes for each vendor, simplifying software requirements.

  • Allows you to directly specify the desired AppSel code, enabling straightforward configuration without requiring Cisco IOS XR software to interpret the mode.

  • Eliminates the extra step of mapping custom vendor codes, reducing delays in supporting new module vendors.

Configuration guidelines and restrictions for AppSel code provisioning

This section explains how to properly configure and manage AppSel code provisioning for optical modules and describes its restrictions.

Configuration guidelines for AppSel code provisioning

You must follow these configuration guidelines for AppSel code provisioning.

  • This feature is not enabled by default. You must configure it to take effect.

  • The maximum number of applications supported depends on the module that is advertised in the AppSel list.

  • For ULH pluggable, the AppSel code is a mandatory parameter. If it is not configured, a "Mandatory Configuration Missing" alarm is triggered and optics laser remains in off state.

  • If you configure an invalid Appsel code during setup, a "Provisioning Failure" alarm will be raised.

  • For AppSel codes that use PCS modulation, the bits-per-symbol value is not supported. The CLI displays 0 for these AppSel codes; this value does not indicate an invalid AppSel code or a provisioning failure.

How AppSel code provisioning works

Summary

The key components involved in the AppSel code provisioning are:

  • Optical side: The optical side or the media side refers to the part of a pluggable module, such as a QDD or other optical transceiver that connects to and communicates with the optical network. It is the interface responsible for converting electrical signals, from the host device, into optical signals for transmission over fiber optic cables, and vice versa for receiving signals.

  • Host side: The host side refers to the part of a pluggable module, such as a QDD or other optical transceiver that interfaces with the host device. A host device is typically a network device like a router, switch, or server. It is responsible for handling and processing electrical signals exchanged between the module and the host device.

  • Optics driver: The entity that collects all supported application codes from the module. Users can see all supported application codes and select any one of the supported application codes.

  • Application codes: The unique codes that represent operational modes of the optical module.

  • Optics Management Agent (MA): The entity that sends the default configuration to the OSA driver if no user configuration is provided. It also manages fallback behavior when no application code is selected.

Workflow

These stages describe how the AppSel code provisioning process works.

  1. AppSel code identifies the optical module modes when the modules are plugged into a router.
  2. AppSel code points to an application descriptor. In this stage, the AppSel code acts as a sequence number for an application descriptor.
  3. The application descriptor defines the configuration. In this stage, the application descriptor describes a functional transmission configuration, including signal processing between host lanes and media lanes.
  4. The AppSel code that contains the media code configures the media side of the optical module.
  5. The host software applies the media code to configure the optical interface of the optical module.
  6. Based on the module's host side interface, you can configure PHY, NPU SerDes, and MacPort.
  7. The host side and media side configurations complete, establishing the datapath.

Result

The host enables AppSel code provisioning as the data path is complete between the host side and media side. This ensures that the optical module operates correctly and efficiently in the desired mode, with proper coordination between the host side interface and the media side.