Release Notes for Cisco C9550 Series Smart Switches, Release Cisco IOS XE 26.2.x

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Updated:July 17, 2026

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Updated:July 17, 2026
 
 
 
 

Cisco C9550 Series Smart Switches, Release Cisco IOS XE 26.2.x. 3

Open issues. 3

Known issues. 3

Compatibility. 3

Supported hardware. 3

Supported software packages. 4

Related resources. 5

Legal information. 8


 

Cisco C9550 Series Smart Switches, Release Cisco IOS XE 26.2.x

Cisco C9550 Series Smart Switches are fixed switches based on the Silicon-One ASIC architecture. These switches deliver high throughput ethernet switching and integrated security for enterprise core and aggregation networks.

Look up Cisco Feature Navigator for the complete list of supported features.

Open issues

There are no open issues in this release.

Known issues

This section lists the limitations for this release.

     Breakout cables are not supported.

     CVR/QSA adapter module is not supported.

     ISSU is not supported.

     Cisco Catalyst Center is not supported.

Compatibility

To view the software compatibility information between Cisco C9550 Series Smart Switches, Cisco Identity Services Engine, and Cisco Prime Infrastructure, go to Cisco C9000 Series Smart Switches Software Version Compatibility Matrix.

Supported hardware

This section lists the hardware support information.

Supported Cisco C9550 Series Smart Switches model numbers

The following table lists the supported hardware models and the default license levels they are delivered with.

Table 1.             Cisco C9550 Series Smart Switches model numbers

Switch model

Description

Introductory release

C9550-24L4CD

  24 x 50/25/10/1G as downlink ports
  4 x 100/40G or 2 x 400G as fixed uplink ports
  2 power supply slots
  5 fan trays
  960 GB SATA SSD local storage
  SVL front-side stacking on all ports

Cisco IOS XE 26.2.1ea

C9550-48L4CD

  48 x QSFP-DD ports of 50/25/10/1G as downlink ports
  4 x 100/40G or 2 x 400G as fixed uplink ports
  2 power supply slots
  5 fan trays
  960 GB SATA SSD local storage
  SVL front-side stacking on all ports

Cisco IOS XE 26.2.1ea

C9550-96L4D

  96 x QSFP-DD ports of 50/25/10/1G as downlinks ports
  4 x QSFP-DD ports that can support 40G/100G/400G
  2 power supply slots
  3 fan trays
  960 GB SATA SSD local storage
  SVL front-side stacking on all ports

Cisco IOS XE 26.2.1ea

Supported optics modules

Cisco Catalyst Series Switches support a wide range of optics and the list of supported optics is updated on a regular basis. Use the Transceiver Module Group (TMG) Compatibility Matrix tool, or consult the tables at this URL for the latest transceiver module compatibility information: https://www.cisco.com/en/US/products/hw/modules/ps5455/products_device_support_tables_list.html

Supported software packages

This section provides information about the release packages associated with Cisco C9550 Series Smart Switches.

Finding the software version

The package files for the Cisco IOS XE software are stored on the system board flash device (flash:).

You can use the show version privileged EXEC command to see the software version that is running on your switch.

Note: Although the show version output always shows the software image running on the switch, the model name shown at the end of this display is the factory configuration and does not change if you upgrade the software license.

You can also use the dir filesystem: privileged EXEC command to see the directory names of other software images that you might have stored in flash memory.

Finding the software Images

Table 2.             Software images

Release

Image type

File name

Cisco IOS XE 26.2.1ea

CISCO9K_IOSXE

cisco9k_iosxe.26.2.01ea1.SPA.bin

No Payload Encryption (NPE)

cisco9k_iosxe_npe.26.2.01ea1.SPA.bin

To download software images, visit the software downloads page: Cisco C9550 Series Smart Switches.

ROMMON versions

ROMMON, also known as the boot loader, is firmware that runs when the device is powered up or reset. It initializes the processor hardware and boots the operating system software (Cisco IOS XE software image). The ROMMON is stored on the following Serial Peripheral Interface (SPI) flash devices on your switch:

     Primary: The ROMMON stored here is the one the system boots every time the device is powered-on or reset.

     Golden: The ROMMON stored here is a backup copy. If the one in the primary is corrupted, the system automatically boots the ROMMON in the golden SPI flash device.

ROMMON upgrades may be required to resolve firmware defects, or to support new features, but there may not be new versions with every release.

Table 3.             ROMMON versions

Release

ROMMON Version

26.2.1 EA

26.1.1.9

Field-programmable gate array version upgrade

A field-programmable gate array (FPGA) is a type of programmable memory device that exists on Cisco switches. They are re-configurable logic circuits that enable the creation of specific and dedicated functions.

To check the current FPGA version, enter the version -v command in ROMMON mode.

Notes:

     Not every software release has a change in the FPGA version.

     The version change occurs as part of the regular software upgrade, and you do not have to perform any other additional steps.

Related resources

This section provides troubleshooting information, links to the product documentation, and licensing information.

Troubleshooting

For the most up-to-date, detailed troubleshooting information, see the Cisco TAC website at Support & Downloads.

Go to Product Support and select your product from the list or enter the name of your product. Look under Troubleshoot and Alerts, to find information for the problem that you are experiencing.

Accessing hidden commands

Hidden commands have always been present in Cisco IOS XE but were not equipped with CLI help. That is, entering a question mark (?) at the system prompt did not display the list of available commands. These commands were only meant to assist Cisco TAC in advanced troubleshooting and were not documented either.

Hidden commands are available under:

     Category 1—Hidden commands in privileged or User EXEC mode. Begin by entering the service internal command to access these commands.

     Category 2—Hidden commands in one of the configuration modes (global, interface and so on). These commands do not require the service internal command.

Further, the following applies to hidden commands under Category 1 and 2:

     The commands have CLI help. Enter enter a question mark (?) at the system prompt to display the list of available commands.

     Note: For Category 1, enter the service internal command before you enter the question mark; you do not have to do this for Category 2.

     The system generates a %PARSER-5-HIDDEN syslog message when a hidden command is used. For example:

*Feb 14 10:44:37.917: %PARSER-5-HIDDEN: Warning!!! 'show processes memory old-header ' is a hidden command.

Use of this command is not recommended/supported and will be removed in future.

Apart from category 1 and 2, there remain internal commands displayed on the CLI, for which the system does NOT generate the %PARSER-5-HIDDEN syslog message.

Important: We recommend that you use any hidden command only under TAC supervision.

If you find that you are using a hidden command, open a TAC case for help with finding another way of collecting the same information as the hidden command (for a hidden EXEC mode command), or to configure the same functionality (for a hidden configuration mode command) using non-hidden commands.

Related documentation

For all support documentation of Cisco C9550 Series Smart Switches, visit Cisco C9550 Series Smart Switches.

For information about Cisco IOS XE, visit Cisco IOS XE.

For information about Cisco IOS XE releases, visit Networking Software (IOS & NX-OS).

For Cisco Validated Designs documents, visit Cisco Validated Design Zone.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at Cisco Feature Navigator.

Communications, services, and additional information

     To receive timely, relevant information from Cisco, sign up at Cisco Profile Manager.

     To get the business results you’re looking for with the technologies that matter, visit Cisco Services.

     To submit a service request, visit Cisco Support.

     To discover and browse secure, validated enterprise-class apps, products, solutions and services, visit Cisco DevNet.

     To obtain general networking, training, and certification titles, visit Cisco Press.

     To find warranty information for a specific product or product family, access Cisco Warranty Finder.

Licensing

For information about licenses required for the features available on Cisco 9000 Series Smart Switches, see Cisco Networking Subscription for Cisco C9000 Series Smart Switches.

Cisco bug search tool

Cisco Bug Search Tool (BST) is a web-based tool that acts as a gateway to the Cisco bug tracking system that maintains a comprehensive list of defects and vulnerabilities in Cisco products and software. BST provides you with detailed defect information about your products and software.

Documentation feedback

To provide technical feedback on this document, or to report an error or omission, send your comments to cisco9k-docfeedback@cisco.com.


 

Legal information

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

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