Smart Licensing Using Policy

About this Guide

This document provides information about Smart Licensing Using Policy such as the concept, architecture, supported products and topologies, configuration, migration, tasks, and troubleshooting only for Cisco Nexus 3550-T switches, Release 10.2(3t).


Note

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product.


Overview

Smart Licensing Using Policy (SLP) is an enhanced version of Smart Licensing, the objective of which is to provide a licensing solution that does not interrupt the operations of your network and to enable a compliance relationship to account for the hardware and software licenses you purchase and use.

SLP is supported starting with Cisco Nexus 3550-T switches, Release 10.2(3t). This document provides information only on SLP.

The primary benefits of this enhanced licensing model are:

  • Seamless day-0 operations

    After a license is ordered, no preliminary steps, such as registration or generation of keys, are required unless you use an export-controlled or enforced license. There are no export-controlled or enforced licenses on Cisco Nexus Switches, and product features can be configured on the device right-away.

  • Consistency in Cisco NX-OS

    Devices that run Cisco NX-OS software have a uniform licensing experience.

  • Visibility and manageability

    Tools, telemetry, and product tagging.

  • Flexible, time series reporting to remain compliant

    Easy reporting options are available, whether you are directly or indirectly connected to Cisco Smart Software Manager (CSSM).

This document provides conceptual, configuration, and troubleshooting information for SLP on Cisco Nexus Switches. For a more detailed overview on Cisco Licensing, go to cisco.com/go/licensingguide.

The conceptual information includes an overview of SLP, supported products, supported topology, and explains how SLP interacts with other features. SLP is a software license management solution that provides a seamless experience with the following aspects of licensing:

  • Purchase licenses: Purchase licenses through the existing channels and use the Cisco Smart Software Manager (CSSM) portal to view product instances and licenses.


    Note

    To simplify your implementation of SLP, provide your Smart Account and Virtual Account information when placing an order for new hardware or software. This allows Cisco to install applicable policies (terms explained in the Concepts section below), at the time of manufacturing.


  • Use: All licenses on Cisco Nexus Switches are unenforced. This means that you do not have to complete any licensing-specific operations, such as registering or generating keys before you start using the software and the licenses that are tied to it. License usage is recorded on your device with timestamps and the required workflows can be completed later.

  • Report license usage to CSSM: Multiple options are available for license usage reporting. You can use the Cisco Smart Licensing Utility (CSLU), or report usage information directly to CSSM. For air-gapped networks, a provision for offline reporting where you download usage information and upload it to CSSM, is also available. The usage report is in plain text XML format.

  • Reconcile: For situations where delta billing applies (purchased versus consumed).

Glossary

The following list describes acronyms and definitions for terms used throughout this document:

  • SLP: Smart License Using Policy

  • CSLU: Cisco Smart Licensing Utility

  • PI: Product Instance

  • SA: Smart Agent

  • UDI: Unique Device Identifier

  • CSSM: Cisco Smart Software Manager

  • LCS: Licensing Crypto Services

  • RUM report: Resource Utilization Measurement (ISO19770-4)

  • Pull mode: A mode in which the CSLU uses netconf/restconf/grpc & YANG or REST to connect to the PI and exchange data.

  • Push mode: A mode in which the PI initiates communications with the CSLU by sending requests to a REST endpoint in the CSLU.

  • Enforced license: Enforced license represents a feature that the product should not allow to be used without authorization.

  • Unenforced license: Unenforced license represents a feature that the product does not enforce use.

  • Reported state: Occurs when the device license state has been reported to be in use to the CSSM. This occurs when shipped or later when the device first reports.

  • Un-Reported state: The device has not yet been reported its license usage to the CSSM and received an acknowledgment back from CSSM.

Architecture

This section explains the various components that can be part of your implementation of SLP.

Product Instance

A product instance, for example, a switch, is a single instance of a Cisco product, which is identified by a Unique Device Identifier (UDI).

A product instance records and reports license usage (Resource Utilization Measurement reports) and provides alerts and system messages about issues such as overdue reports and communication failures. Resource Utilization Measurement (RUM) reports and usage data are securely stored in the product instance.

Throughout this document, the term product instance refers to all supported physical and virtual product instances, unless noted otherwise. For information about the product instances that are within the scope of this document, see Supported Products.

CSSM

Cisco Smart Software Manager (CSSM) is a portal that enables you to manage all your Cisco software licenses from a centralized location. CSSM helps you manage current requirements and review usage trends to plan for future license requirements.

You can access the CSSM Web UI at https://software.cisco.com. Navigate to Manage licenses link.

See Supported Topologies to know about the different ways in which you can connect to CSSM.

In CSSM you can perform the following:

  • Create, manage, or view virtual accounts

  • Create and manage Product Instance Registration Tokens

  • Transfer licenses between virtual accounts or view licenses

  • Transfer, remove, or view product instances

  • Run reports against your virtual accounts

  • Modify your email notification settings

  • View overall account information

CSLU

Cisco Smart License Utility (CSLU) is a Windows-based reporting utility that provides aggregate licensing workflows. This utility performs the following key functions:

  • Provides options relating to how workflows are triggered. The workflows can be triggered by CSLU or by the product instance.

  • Collects usage reports from the product instance and uploads these usage reports to the corresponding Smart Account or Virtual Account, online or offline, using files. Similarly, the RUM report ACK is collected online or offline and sent back to the product instance.

  • Sends authorization code requests to CSSM and receives authorization codes from CSSM, if applicable.

CSLU can be part of your implementation in the following ways:

  • Install the Windows application to use CSLU as a standalone tool that is connected to CSSM.

  • Install the Windows application to use CSLU as a standalone tool that is disconnected from CSSM. With this option, the required usage information is downloaded to a file and then uploaded to CSSM. This is suited for air-gapped networks.

SSM On-Prem

Smart Software Manager On-Prem (SSM On-Prem) is an asset manager, which works in conjunction with CSSM. It enables you to administer products and licenses on your premises instead of having to directly connect to CSSM.

Information about the required software versions to implement SLP with SSM On-Prem, is provided below:

Minimum Required SSM On-Prem Version for SLP Minimum Required Cisco NX-OS Version
Version 8, August, 2021 Cisco NX-OS Release 10.2(3t)

1

The minimum required SSM On-Prem version. This means support continues on all subsequent releases - unless noted otherwise.

2

The minimum required software version on the product instance. This means support continues on all subsequent releases - unless noted otherwise.

For more information about SSM On-Prem, see Smart Software Manager On-Prem on the Software Download page. Hover over the .iso image to display the documentation links to the following guides:

  • Installation Guide – SSM On-Prem Installation Guide

  • Release Notes – Cisco Smart Software Manager On-Prem Release Notes

  • User Guide – Smart Software Manager On-Prem User Guide

  • Console Guide – Smart Software Manager On-Prem Console Reference Guide

  • Quick Start Guide – Smart Software Manager On-Prem Quick Start Installation Guide

Guidelines and Limitations

The SLP feature has the following guidelines and limitations:

  • CSLU-initiated communication/pull mode is not supported in Cisco Nexus 3550-T switches, Release 10.2(3t).

  • CSLU configuration is mandatory if callhome is not configured and the device is not registered with CSSM, when moving from pre-SLP releases to SLP in Cisco Nexus 3550-T switches, Release 10.2(3t). For more information, see Connected to CSSM Through CSLU.

  • Standalone CSLU does not support multi-tenancy, it supports only single SA/VA. However, On-Prem CSLU supports multi-tenancy.

  • For auto discovery, only one CSLU can be used in the network.

  • SLP MIB is not supported.

  • Only CSLU mode of transport is supported on On-Prem.

  • While using the transport mode as CSLU, if licenses do not get released from the SA/VA after write-erase and reload of the switch, it is recommended to delete the Product Instance from the SA/VA.

  • When a switch is being reset to factory defaults using “write erase” command, it is recommended to do a “License smart factory reset” before reloading the switch.

  • Cisco Nexus 3550-T switches, Release 10.2(3t) supports only the SLP licensing mode.

Concepts

This section explains the key concepts of SLP.

License Enforcement Types

The only enforcement type supported on Cisco Nexus 3550-T switches, Release 10.2(3t) platform switches is Unenforced or Not Enforced. Unenforced licenses do not require authorization before use in air-gapped networks or in connected networks. The terms of use for such licenses are as per the end user license agreement (EULA).


Note

Enforced and Export licenses are not supported on Cisco Nexus 3550-T switches, Release 10.2(3t) platform switches.


License Duration

This refers to the duration or term for which a purchased license is valid. A given license may belong to any one of the enforcement types mentioned above and be valid for the following durations:

  • Perpetual: There is no expiration date for such a license.

  • Subscription: The license is valid only until a certain date.

Policy

A policy provides the product instance with these reporting instructions:

  • License usage report acknowledgment requirement (Reporting ACK required): The license usage report is known as a RUM Report and the acknowledgment is referred to as an ACK (See RUM Report and Report Acknowledgement). This is a yes or no value that specifies if the report for this product instance requires CSSM acknowledgment. The default policy is always set to yes.

  • First report requirement (days): The first report must be sent within the duration specified here.

  • Reporting frequency (days): The subsequent report must be sent within the duration specified here.

  • Report on change (days): If there is a change in license usage, a report must be sent within the duration specified here.

Understanding the Policy Selection

CSSM determines the policy that is applied to a product instance. Only one policy is in use at a given point in time. The policy and its values are based on several factors, including the licenses being used.

Cisco default is the default policy that is always available in the product instance. If no other policy is applied, the product instance applies this default policy. Table 1 shows the Cisco default policy values.

While you cannot configure a policy, you can request for a customized one, by contacting the Cisco Global Licensing Operations team. Go to Support Case Manager. Click OPEN NEW CASE > Select Software Licensing. The licensing team will contact you to start the process or for any additional information. Customized policies are also made available through your Smart account in CSSM.


Note

To know which policy is applied (the policy in-use) and its reporting requirements, enter the show license all command in privileged EXEC mode.


Table 1. Policy Cisco default for NX-OS
Policy: Cisco Default Default Policy Values
Unenforced/Non-Export

Reporting ACK required: Yes

First report requirement (days): 90

Reporting frequency (days): 365

Report on change (days): 90

RUM Report and Report Acknowledgment

A Resource Utilization Measurement report (RUM report) is a license usage report, which the product instance generates, to fulfill reporting requirements as specified by the policy.

An acknowledgment (ACK) is a response from CSSM and provides information about the status of a RUM report.

The policy that is applied to a product instance determines the following reporting requirements:

  • Whether a RUM report is sent to CSSM, and the maximum number of days provided to meet this requirement.

  • Whether the RUM report requires an acknowledgment (ACK) from CSSM.

  • The maximum number of days provided to report a change in license consumption.

A RUM report sent to CSSM from device/CSLU may be accompanied by other requests.


Note

System logs are generated at X and X-30 days if reporting is not done. X is the reporting interval per the policy.


Below is the example for RUM:
<?xml version="1.0" encoding="UTF-8"?>
<smartLicense>
<RUMReport>
<![CDATA[
{
   "payload":"{
      "asset_identification":{
         "asset":{
            "name":"regid.2021-12.com.cisco.N3550_T,1.0_02ed5969-299b-49ea-9097-d4219b0d03a0"
          },
          "instance":{
             "sudi":{
                "udi_pid":"N35-T-48X",
                "udi_serial_number":"EXATRI-A-01828"
                }
           },
           "signature":{
              "signing_type":"builtin",
              "key":"regid.2021-12.com.cisco.N3550_T,1.0_02ed5969-299b-49ea-9097-d4219b0d03a0",
              "value":"yMf1IwYjQoI9DXbM2z0NwxptvPqAa4GEbnfGIe9679A="
           }
         },
        "meta":{
           "entitlement_tag":"regid.2021-12.com.cisco.NX_OS_ESSENTIALS_Nexus3550_T,1.0_1c469435-bfdb-4377-b402-6873b39d860b",
           "report_id":1659085457,
           "software_version":"10.2(3)I9(1)",
           "ha_udi":[
              {
                 "role":"Active",
                 "sudi":{
                 "udi_pid":"N35-T-48X",
                 "udi_serial_number":"EXATRI-A-01828"
               }
             }
          ]
        },
        "measurements":[
         {
            "log_time":1659085460,
            "metric_name":"ENTITLEMENT",
            "start_time":1659085460,
            "end_time":1659085461,
            "sample_interval":1,
            "num_samples":1,
            "meta":{
               "termination_reason":"CurrentUsageRequested"
            },
            "value":{
               "type":"COUNT",
               "value":"1"
            }
         }
      ]
   },
   "header":{
      "type":"rum"
   },
   "signature":{
      "sudi":{
         "udi_pid":"N35-T-48X",
         "udi_serial_number":"EXATRI-A-01828"
      },
      "signing_type":"builtin",
      "key":"regid.2021-12.com.cisco.N3550_T,1.0_02ed5969-299b-49ea-9097-d4219b0d03a0",
      "value":"3CiyiukUQwPKj54KMhOV9+Fq4munp5SzyhjKe+AiYU8="
   }
}
]]>
</RUMReport>
</smartLicense>
Below is the example for RUM ACK
<?xml version="1.0" encoding="UTF-8"?>
<smartLicense>
   <smartLicenseRumAck>
      <data>
        <![CDATA[[
        {
           "status_code":"OK",
           "status_message":"Rum Report is accepted.",
           "localized_message":"Rum Report is accepted.",
           "product_instance_identifier":"ebd10898-aa6d-4697-a7bc-5d4a0f24d775",
           "sudi":{
              "udi_pid":"N35-T-48X",
              "udi_serial_number":"EXATRI-A-01828"
           },
           "report_id":1659085457,
           "correlation_id":"62e3a463ff87b0c4989af00aa4d526bc-fdba9fd67bb17e0c",
           "subscription_id":null
        }      
      ]]]>
    </data>
    <signature>MEQCIAO/5kmtTQOVyUWWkRuuLR7FRC5BNtW4ZHp2XqyKixOPAiBOZjmZ8vfmMrqU9c4RplKgwJfIqKwnqP3BiWdO6udScQ==</signature>
   </smartLicenseRumAck>
   <smartLicensePolicy>
     <policyCode>
         <name>SLE Policy</name>
         <version>5</version>
         <flag></flag>
         <datestamp>2021-10-25T18:50:17</datestamp>      
         <ackRequired>yes</ackRequired>
         <subscription>
            <firstTimeReport>120</firstTimeReport>
            <onGoingReporting>111</onGoingReporting>
            <reportOnMACD>111</reportOnMACD>
         </subscription>
         <perpetual>
            <firstTimeReport>30</firstTimeReport>
            <onGoingReporting>60</onGoingReporting>
            <reportOnMACD>60</reportOnMACD>
         </perpetual>
         <enforced>
            <onGoingReporting>90</onGoingReporting>
            <reportOnMACD>60</reportOnMACD>
         </enforced>
         <export>
            <onGoingReporting>30</onGoingReporting>
            <reportOnMACD>30</reportOnMACD>
         </export>
         <generic>
            <firstTimeReport>90</firstTimeReport>
            <onGoingReporting>365</onGoingReporting>
            <reportOnMACD>120</reportOnMACD>
         </generic>
     </policyCode>
    <signature>MEYCIQC5RWI0zYVCfSnjxtopYjNFlQPbF4LG6egvHMmqmnalZgIhAIwxJzxIxWmj+NAYqO4Y14CRixKktiUs/SwWtWk8RybG</signature>
   </smartLicensePolicy>
   <smartLicenseAccountInfo>
      <customerInfo>
         <timestamp>1659085985394</timestamp>
         <smartAccount>BU Production Test</smartAccount>
         <virtualAccount>N39K_SA_Testing_01</virtualAccount>
         <smartAccountId>10560</smartAccountId>
         <virtualAccountId>506899</virtualAccountId>
         <smartAccountDomain>buproductiontest.cisco.com</smartAccountDomain>
      </customerInfo>
    <signature>MEYCIQDEgcsiwUDiF8uLcDOPNQ3TCngiG8F99/27WtQ4KoEOugIhANsv++syb1DThxC0h4hNyujR1YFCpagDKYJh836fHK+B</signature>
   </smartLicenseAccountInfo>
   <correlationID>ngnx-7cc93b23493a0a7eba0d5f12a9c85be7</correlationID>
</smartLicense>

Trust Code

Trust code is a UDI-tied public key with which the product instance signs a RUM report. This prevents tampering and ensures data authenticity.

Supported Topologies

This section describes the various ways in which you can implement SLP. For each topology, refer to the accompanying overview to know how the setup is designed to work, and refer to the considerations and recommendations, if any.

Choosing a Topology

The following table allows you to choose a topology depending on your network deployment.

Topology

Recommendations

Topology 1: Connected to CSSM Through CSLU

Use this topology when you do not want the switches to be directly connected to CSSM. This topology will support only one SA/VA combination.

Topology 2: Connected Directly to CSSM

Use this topology when you have switches that are already registered to CSSM and need to continue in the same mode. If you need to continue using this topology after upgrading to SLP, then Smart Transport is the preferred transport method.

Topology 3: CSLU Disconnected from CSSM

Use this topology when you need to manage or view license consumption locally. You can also use multiple VA.

Topology 4: No Connectivity to CSSM and No CSLU

Use this topology when you want to collect licensing information from a single source and when there is no connectivity to CSSM. You cannot view license consumption locally. Also, only a single VA can be used.

Topology 5: Connected to CSSM Through SSM On-Prem

Use this topology when you want to collect licensing information from each switch in the network and when there is no connectivity to CSSM.

Topology 6: SSM On-Prem Disconnected from CSSM

Use this topology when you want to manage or view licenses from a single source. You can view license consumption locally. You can also use multiple SA/VA combinations.

Topology 1: Connected to CSSM Through CSLU

Overview:

Here, product instances in the network are connected to CSLU, and CSLU becomes the single point of interface with CSSM. A product instance can be configured to push the required information to CSLU.

The communication between PI to CSLU, and CSLU to CSSM occurs online through HTTPS mode. The Product Instance Service Port is 8182, and the REST API Port number is 8180.

Product instance-initiated communication (push): A product instance initiates communication with On-Prem CSLU, by connecting to a REST endpoint in CSLU. Data that is sent includes RUM reports. You can configure the product instance to automatically send RUM reports to CSLU at required intervals.

Figure 1. Topology: Connected to CSSM Through CSLU

Considerations or Recommendations:

Choose the method of communication depending on your network’s security policy.

Where to Go Next:

To implement this topology, see Connected to CSSM Through CSLU.

Topology 2: Connected Directly to CSSM

Overview:

This topology is available in the earlier version of Smart Licensing and continues to be supported with SLP.

Here, you establish a direct and trusted connection from a product instance to CSSM. The direct connection requires network availability to CSSM. For the product instance to then exchange messages and communicate with CSSM, configure one of the transport options available with this topology (described below). Lastly, the establishment of trust requires the generation of a token from the corresponding Smart Account and Virtual Account in CSSM, and installation on the product instance.

You can configure a product instance to communicate with CSSM in the following ways:

  • Use Smart transport to communicate with CSSM

    Smart transport is a transport method where a Smart Licensing (JSON) message is contained within an HTTPs message, and exchanged between a product instance and CSSM, to communicate. The following Smart transport configuration options are available:

    • Smart transport: In this method, a product instance uses a specific Smart transport licensing server URL. This must be configured exactly as shown in the workflow section.

    • Smart transport through an HTTPS proxy: In this method, a product instance uses a proxy server to communicate with the licensing server, and eventually, CSSM.

  • Use Callhome to communicate with CSSM.

    Callhome provides e-mail-based and web-based notification of critical system events. This method of connecting to CSSM is available in the earlier Smart Licensing environment and remains available with SLP. The following Callhome configuration options are available:

    • Direct cloud access: In this method, a product instance sends usage information directly over the internet to CSSM; no additional components are needed for the connection.

    • Direct cloud access through an HTTPS proxy: In this method, a product instance sends usage information over the internet through a proxy server - either a Callhome Transport Gateway or an off-the-shelf proxy (such as Apache) to CSSM.

Figure 2. Topology: Connected Directly to CSSM


Considerations or Recommendations:

Smart transport is the recommended transport method when directly connecting to CSSM. This recommendation applies to:

  • New deployments.

  • Earlier licensing models. Change configuration after migration to SLP.

  • Registered licenses that currently use the Callhome transport method. Change configuration after migration to SLP.

  • Evaluation or expired licenses in an earlier licensing model. Change configuration after migration to SLP.

To change configuration after migration, see Connected Directly to CSSM > Product Instance Configuration > Configure a connection method and transport type > Option 1.

Where to Go Next:

To implement this topology, see Connected Directly to CSSM.

Topology 3: CSLU Disconnected from CSSM

Overview:

Here, a product instance communicates with CSLU, and you can implement the product instance-initiated communication. The other side of the communication, between CSLU and CSSM, is offline. CSLU provides you with the option of working in a move that is disconnected from CSSM.

Communication between CSLU and CSSM is sent and received in the form of signed files that are saved offline and then uploaded to or downloaded from CSLU or CSSM.

Figure 3. Topology: CSLU Disconnected from CSSM

Considerations or Recommendations:

None.

Where to Go Next:

To implement this topology, see CSLU Disconnected from CSSM.

Topology 4: No Connectivity to CSSM and No CSLU

Overview:

Here you have a product instance and CSSM disconnected from each other, and without any other intermediary utilities or components. All communication is in the form of uploaded and downloaded files.

Figure 4. Topology: No Connectivity to CSSM and No CSLU

Considerations or Recommendations:

This topology is suited to a high-security deployment where a product instance cannot communicate online, with anything outside its network.

Where to Go Next:

To implement this topology, see No Connectivity to CSSM and No CSLU.

Topology 5: Connected to CSSM Through SSM On-Prem

Overview:

Here, product instances in the network are connected to Smart Software Manager (SSM) On-Prem, and SSM On-Prem becomes the single point of interface with CSSM. A product instance can be configured to push the required information to SSM On-Prem.

Product instance-initiated communication (push): A product instance initiates communication with SSM On-Prem, by connecting to a REST endpoint in SSM On-Prem. Data that is sent includes RUM reports. You can configure the product instance to automatically send RUM reports to SSM On-Prem at required intervals.

Figure 5. Topology: Connected to CSSM Through SSM On-Prem

Considerations or Recommendations:

Choose the method of communication depending on your network’s security policy.

Where to Go Next:

To implement this topology, see Connected to CSSM Through SSM On-Prem .

Topology 6: SSM On-Prem Disconnected from CSSM

Overview:

Here, a product instance communicates with SSM On-Prem, and you can implement the product instance-initiated communication. The other side of the communication, between SSM On-Prem and CSSM, is offline. SSM On-Prem provides you with the option of working in a mode that is disconnected from CSSM.

Communication between SSM On-Prem and CSSM is sent and received in the form of signed files that are saved offline and then uploaded to or downloaded from SSM On-Prem or CSSM.

Figure 6. Topology: SSM On-Prem Disconnected from CSSM

Considerations or Recommendations:

None.

Where to Go Next:

To implement this topology, see SSM On-Prem Disconnected from CSSM.

After Topology Selection

After you have selected a topology, see Configuring Smart Licensing Using Policy . These workflows are only for new deployments. They provide the simplest and fastest way to implement a topology.

If you are migrating from an existing licensing model, see Migrating to Smart Licensing Using Policy.

If you want to perform any additional configuration tasks, for instance, if you want to configure different license, or use add-on license, or if you want to configure a narrower reporting interval, see the Tasks: Smart Licensing Using Policy. Check the Supported Topologies, before you proceed.

Supported Products

This section provides information about the Cisco NX-OS product instances that are within the scope of this document and support SLP. All models (Product IDs or PIDs) in a product series are supported – unless indicated otherwise.

Table 2. Supported Product Instances: Cisco Nexus Switches
Cisco Nexus Switches When Support was Introduced
Cisco Nexus 3550-T Switches

Cisco Nexus 3550-T, Release 10.2(3t)


Note

For the hardware that are not supported, refer to Cisco Nexus 3550-T Switches Release Notes, Release 10.2(3t).


Interactions with Other Features

Upgrades

This section describes how upgrade or migration to SLP is handled. To migrate to SLP, you must upgrade to a software version that supports SLP.

In Cisco Nexus 3550-T switches, Release 10.2(3t) SLP is the only mode of licensing available to the customers when upgrading from the previous version Cisco Nexus 3550-T switches, Release 10.1(2t).

Downgrades

To downgrade, you must downgrade the software version on the product instance.

Upgrade and Then Downgrade

If you upgrade to a software version that supports SLP and then downgrade to any of the earlier release, and any product features you have configured on the product instance are preserved – only the features and functions that are available with SLP are not available anymore.

In Cisco Nexus 3550-T switches, Release 10.2(3t) SLP is not available after performing a downgrade.