Caveats describe unexpected behavior in Cisco IOS-XE releases. Caveats listed as open in a prior release are carried forward to the next release as either open or resolved.

This section lists the supported and unsupported features.

With Cisco Catalyst 9500 Series Switches and Cisco Catalyst 9500 Series Switches - High Performance: If a feature is not supported on a switch model, you do not have to factor in any limitations or restrictions that may be listed here. If limitations or restrictions are listed for a feature that is supported, check if model numbers are specified, to know if they apply. If model numbers are not specified, the limitations or restrictions apply to all models in the series.

• Auto negotiation

  Auto negotiation (the speed auto command) and half duplex (the duplex half command) are not supported on GLC-T or GLC-TE transceivers for 10 Mbps and 100 Mbps speeds. This applies only to the C9500-48Y4C and C9500-24Y4C models of the series.

  We recommend not changing Forward Error Correction (FEC) when auto negotiation is ON. This is applicable to 100G/40G/25G CU cables on the C9500-32C, C9500-32QC, C9500-24Y4C and C9500-48Y4C models of the series.

• Control Plane Policing (CoPP): The show running-config command does not display information about classes configured under system-cpp policy, when they are left at default values. Use the show policy-map system-cpp-policy or the show policy-map control-plane commands in privileged EXEC mode instead.

• Cisco StackWise Virtual

  • On Cisco Catalyst 9500 Series Switches, when Cisco StackWise Virtual is configured, breakout ports using 4X10G breakout cables, or the Cisco QSFP to SFP or SFP+ Adapter (QSA) module can only be used as data ports; they cannot be used to configure StackWise Virtual links (SVLs) or dual-active detective (DAD) links.

  • On Cisco Catalyst 9500 Series Switches - High Performance,

    • When Cisco StackWise Virtual is configured, breakout ports using 4X25G or 4X10G breakout cables can only be used as data ports; they cannot be used to configure SVLs or DAD links.

    • When Cisco StackWise Virtual is configured, Cisco QSA module with 10G SFP modules can be used as data ports and to configure SVLs or DAD links.

    • When Cisco StackWise Virtual is configured, Cisco QSA module with 1G SFP modules can be used as data ports and to configure DAD links; they cannot be used to configure SVLs since SVLs are not supported on 1G interfaces.

• Cisco TrustSec restrictions: Cisco TrustSec can be configured only on physical interfaces, not on logical interfaces.

• Flexible NetFlow limitations

  • You cannot configure NetFlow export using the Ethernet Management port (GigabitEthernet0/0).

  • You can not configure a flow monitor on logical interfaces, such as layer 2 port-channels, loopback, tunnels.

  • You can not configure multiple flow monitors of same type (ipv4, ipv6 or datalink) on the same interface for same direction.

• Hardware Limitations (Optics):

  • 1G with Cisco QSA Module (CVR-QSFP-SFP10G) is not supported on the uplink ports of the C9500-24Y4C and C9500-48Y4C models.

  • Installation restriction for SFP-10G-T-X module on C9500-24Y4C and C9500-48Y4C: Only eight SFP-10G-T-X modules are supported at a time. If you insert a ninth SFP-10G-T-X module in a lower numbered port than the existing active eight SFP-10G-T-X module, a reload will bring up the ninth transceiver and moves the last existing port with SFP-10G-T-X module to error disabled state. This happens due to the order of sequence ports link bring up where the lower numbered port brings up the link first. This limitation applies in standalone and in Cisco StackWise Virtual setup with two C9500-24Y4C or C9500-48Y4C switches. Each switch can have eight SFP-10G-T-X modules.

    The following error displays on the console if you insert a ninth module with eight active modules:

    “%IOMD_ETHER_GEIM-4-MAX_LIMIT_XCVR: R0/0: iomd: Number of SFP-10G-T-X that can be supported has reached the max limit of 8, transceiver is err-disabled. Unplug the transceiver in interface TwentyFiveGigE1/0/29

  • SFP-10G-T-X supports 100Mbps/1G/10G speeds based on auto negotiation with the peer device. You cannot force speed settings from the transceiver.

• Hardware Limitations:

  • Use the MODE button to switch-off the beacon LED.

  • All port LED behavior is undefined until interfaces are fully initialized.

  • The following limitations apply to Cisco QSA Module (CVR-QSFP-SFP10G) when Cisco 1000Base-T Copper SFP (GLC-T) or Cisco 1G Fiber SFP Module for Multimode Fiber are plugged into the QSA module:

    • 1G Fiber modules over QSA do not support autonegotiation. Auto-negotiation should be disabled on the far-end devices.

    • Although visible in the CLI, the command [no] speed nonegotiate is not supported with 1G Fiber modules over QSA.

    • Only GLC-T over QSA supports auto-negotiation.

    • GLC-T supports only port speed of 1000 Mb/s over QSA. Port speeds of 10/100-Mb/s are not supported due to hardware limitation.

  • When you use Cisco QSFP-4SFP10G-CUxM Direct-Attach Copper Cables, autonegotiation is enabled by default. If the other end of the line does not support autonegotation, the link does not come up.

  • Autonegotiation is not supported on HundredGigabitEthernet1/0/49 to HundredGigabitEthernet1/0/52 uplink ports of the C9500-48Y4C models, and HundredGigabitEthernet1/0/25 to HundredGigabitEthernet1/0/28 uplink ports of the C9500-24Y4C models. Disable autonegotiation on the peer device if you are using QSFP-H40G-CUxx and QSFP-H40G-ACUxx cables.

  • For QSFP-H100G-CUxx cables, the C9500-48Y4C and C9500-24Y4C models support the cables only if both sides of the connection are either C9500-48Y4C or C9500-24Y4C.

  • For C9500-32C model, the power supply with serial number starting with POG has two fans and the power supply with serial number starting with QCS has a single fan. When you use show environment status command, the fan status of one fan is always displayed as N/A when the power supply with single fan is installed into the power supply slot. See Configuring Internal Power Supplies.

• Interoperability limitations: When you use Cisco QSFP-4SFP10G-CUxM Direct-Attach Copper Cables, if one end of the 40G link is a Catalyst 9400 Series Switch and the other end is a Catalyst 9500 Series Switch, the link does not come up, or comes up on one side and stays down on the other. To avoid this interoperability issue between devices, apply the the speed nonegotiate command on the Catalyst 9500 Series Switch interface. This command disables autonegotiation and brings the link up. To restore autonegotiation, use the no speed nonegotiation command.

• In-Service Software Upgrade (ISSU)

  • Within a major release train (16.x or 17.x or 18.x ), ISSU is supported between any two EMs that are released not more than 3 years apart.

  • Within a major release train, ISSU is supported from:

    • Any EM (EM1, EM2, EM3) to another EM (EM1, EM2, EM3)

      Example: 16.9.x to 16.12.x, 17.3.x to 17.6.x, 17.6.x to 17.9.x

    • Any release within the same EM

      Example: 16.9.2 to 16.9.3 or 16.9.4 or 16.9.x, 16.12.1 to 16.12.2 or 16.12.3 or 16.12.x, 17.3.1 to 17.3.2 or 17.3.3 or 17.3.x

  • Between major release trains, ISSU is not supported from:

    • An EM of a major release train to an EM of another major release train

      Example: 16.x.x to 17.x.x or 17.x.x to 18.x.x is not supported

    • An SM to EM or EM to SM

      Example: 16.10.x or 16.11.x to 16.12.x is not supported

  • ISSU is not supported on engineering special releases and .s (or similar) images.

  • ISSU is not supported between Licensed Data Payload Encryption (LDPE) and No Payload Encryption (NPE) Cisco IOS XE software images.

  • ISSU downgrades are not supported.

  • On Cisco Catalyst 9500 Series Switches - High Performance (C9500-24Y4C, C9500-32C, C9500-32QC, and C9500-48Y4C), ISSU with Cisco StackWise Virtual is supported only starting from Cisco IOS XE Gibraltar 16.12.1. Therefore, ISSU upgrades can be performed only starting from this release to a later release.

  • While ISSU allows you to perform upgrades with zero downtime, we recommend you to do so during a maintenance window only.

  • If a new feature introduced in a software release requires a change in configuration, the feature should not be enabled during ISSU.

  • If a feature is not available in the downgraded version of a software image, the feature should be disabled before initiating ISSU.

• QoS restrictions

  The following restrictions apply to UADP-powered Catalyst 9500 and Catalyst 9500 High Performance models only.

  • When configuring QoS queuing policy, the sum of the queuing buffer should not exceed 100%.

  • Policing and marking policy on sub interfaces is supported.

  • Marking policy on switched virtual interfaces (SVI) is supported.

  • QoS policies are not supported for port-channel interfaces, tunnel interfaces, and other logical interfaces.

• Secure Shell (SSH)

  • Use SSH Version 2. SSH Version 1 is not supported.

  • When the device is running SCP and SSH cryptographic operations, expect high CPU until the SCP read process is completed. SCP supports file transfers between hosts on a network and uses SSH for the transfer.

    Since SCP and SSH operations are currently not supported on the hardware crypto engine, running encryption and decryption process in software causes high CPU. The SCP and SSH processes can show as much as 40 or 50 percent CPU usage, but they do not cause the device to shutdown.

• Smart Licensing Using Policy: Starting with Cisco IOS XE Amsterdam 17.3.2a, with the introduction of Smart Licensing Using Policy, even if you configure a hostname for a product instance or device, only the Unique Device Identifier (UDI) is displayed. This change in the display can be observed in all licensing utilities and user interfaces where the hostname was displayed in earlier releases. It does not affect any licensing functionality. There is no workaround for this limitation.

  The licensing utilities and user interfaces that are affected by this limitation include only the following: Cisco Smart Software Manager (CSSM), Cisco Smart License Utility (CSLU), and Smart Software Manager On-Prem (SSM On-Prem).

  This limitation is removed from Cisco IOS XE Cupertino 17.9.1. If you configure a hostname and disable hostname privacy (no license smart privacy hostname global configuration command), hostname information is sent from the product instance and displayed on the applicable user interfaces (CSSM, CSLU, SSM On-Prem). For more information, see the command reference for this release.

• TACACS legacy command: Do not configure the legacy tacacs-server host command; this command is deprecated. If the software version running on your device is Cisco IOS XE Gibraltar 16.12.2 or a later release, using the legacy command can cause authentication failures. Use the tacacs server command in global configuration mode.

• USB Authentication: When you connect a Cisco USB drive to the switch, the switch tries to authenticate the drive against an existing encrypted preshared key. Since the USB drive does not send a key for authentication, the following message is displayed on the console when you enter password encryption aes command:

  Device(config)# password encryption aes
  Master key change notification called without new or old key

• Catatyst 9000 Series Switches support MACsec switch-to-switch connections. We do not recommend configuring MACsec switch-to-host connections in an overlay network. For assistance with an existing switch-to-host MACsec implementation or a design review, contact your Cisco Sales Representative or Channel Partner.

• VLAN Restriction: It is advisable to have well-defined segregation while defining data and voice domain during switch configuration and to maintain a data VLAN different from voice VLAN across the switch stack. If the same VLAN is configured for data and voice domains on an interface, the resulting high CPU utilization might affect the device.

• Wired Application Visibility and Control limitations:

  • NBAR2 (QoS and Protocol-discovery) configuration is allowed only on wired physical ports. It is not supported on virtual interfaces, for example, VLAN, port channel nor other logical interfaces.

  • NBAR2 based match criteria ‘match protocol’ is allowed only with marking or policing actions. NBAR2 match criteria will not be allowed in a policy that has queuing features configured.

  • ‘Match Protocol’: up to 256 concurrent different protocols in all policies.

  • NBAR2 and Legacy NetFlow cannot be configured together at the same time on the same interface. However, NBAR2 and wired AVC Flexible NetFlow can be configured together on the same interface.

  • Only IPv4 unicast (TCP/UDP) is supported.

  • AVC is not supported on management port (Gig 0/0)

  • NBAR2 attachment should be done only on physical access ports. Uplink can be attached as long as it is a single uplink and is not part of a port channel.

  • Performance: Each switch member is able to handle 500 connections per second (CPS) at less than 50% CPU utilization. Above this rate, AVC service is not guaranteed.

  • Scale: Able to handle up to 5000 bi-directional flows per 24 access ports and 10000 bi-directional flows per 48 access ports.

• YANG data modeling limitation: A maximum of 20 simultaneous NETCONF sessions are supported.

• Embedded Event Manager: Identity event detector is not supported on Embedded Event Manager.

• On the Cisco Catalyst 9500X Series Switches, TCAM space will not be reserved for different features. The available TCAM space will be shared across the features.

• The File System Check (fsck) utility is not supported in install mode.

• The command service-routing mdns-sd is being deprecated. Use the mdns-sd gateway command instead.

This section provides information about the licensing packages for features available on Cisco Catalyst 9000 Series Switches.

To view the software compatibility information between Cisco Catalyst 9500 Series Switches, Cisco Identity Services Engine, Cisco Access Control Server, and Cisco Prime Infrastructure, go to Cisco Catalyst 9000 Series Switches Software Version Compatibility Matrix.

This section provides information about software, images, and ROMMON, and Field-Programmable Gate Array (FGPA) versions.

This section covers the various aspects of upgrading or downgrading the device software.

 Note

You cannot use the Web UI to install, upgrade, or downgrade device software.

In-Service Software Upgrade (ISSU) is a process that upgrades an image to another image on a device while the network continues to forward packets. ISSU helps network administrators avoid a network outage when performing a software upgrade. ISSU is supported in install mode.

ISSU is supported in dual SUP HA and StackWise Virtual system. In-Service Software Upgrade is performed either in a single step or in three-steps.

ISSU Support between Releases

• Within a major release train (16.x or 17.x or 18.x ), ISSU is supported between any two Extended Maintenance (EM) releases that are released not more than 3 years apart.

• Within a major release train, ISSU is supported from:

  • Any EM (EM1, EM2, EM3) release to another EM (EM1, EM2, EM3) release

    Example:

    16.9.x to 16.12,

    17.3.x to 17.6.x, 17.3.x to 17.9.x, 17.3.x to 17.12.x and so on

    17.6.x to 17.9.x, 17.6.x to 17.12.x, 17.6.x to 17.15.x and so on

    17.9.x to 17.12.x, 17.9.x to 17.15.x and so on

  • Any release within the same EM release

    Example:

    16.9.2 to 16.9.3 or 16.9.4 or 16.9.x

    16.12.1 to 16.12.2 or 16.12.3 or 16.12.x

    17.3.1 to 17.3.2 or 17.3.3 or 17.3.x

• ISSU Recommendation: From any EM recommended release on CCO to current EM Recommended release on CCO.

See In-Service Software Upgrade (ISSU) for information on ISSU support for Catalyst platforms and Software Lifecycle Support Statement for information extended and standard maintenance releases.

For information about feature scaling guidelines, see the Cisco Catalyst 9500 Series Switches datasheet at:

https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-9500-series-switches/datasheet-c78-738978.html