Cisco Nexus 9300 Series Switches: Features & Generic Troubleshooting Commands

Cisco Nexus 9300 Series Switches: Features & Generic Troubleshooting Commands


This article provides a comprehensive document for  enabling features  and Generic troubleshoot commands on Cisco Nexus 9300 Series switches operating NX-OS . The scope of this  includes physical Ethernet ports, Layer 2&3  , management interfaces.

1.Product Overview

The Cisco Nexus 9300 Series represents a family of high-performance, fixed-configuration Ethernet switches engineered to meet the rigorous demands of contemporary data center architectures. Purpose-built for scalable and resilient operations, these platforms deliver high-density, wire-speed, nonblocking throughput to ensure deterministic performance for latency-sensitive applications.





2.Initial Troubleshooting Checklist

Follow these steps for a systematic approach to interface issues:

  1. Verify Physical Media: Inspect cables and connectors for any visible damage.
  2. Check SFPs/Transceivers: Ensure you are using only Cisco-authorized SFPs. Verify that they are securely seated and not defective.
  3. Enable the Port: Confirm the interface is not administratively down by using the no shutdown command in interface configuration mode.
  4. Check Interface State: Use the show interface <interface> command to see the current status (e.g., up, down, err disabled).
  5. Review Port Group Configuration: If the port is in a dedicated port group, ensure no cables are connected to the other three ports in that group.
  6. Baseline Counters: To get accurate data for error analysis, clear the interface counters to reset the baseline:

3. Common CLI Commands for Troubleshooting

  • show interface <interface>:Displays detailed status, speed, duplex, VLAN, and error statistics.
  • show interface status: Provides a summary of interface administrative status and operational status.
  • show interface counters: Displays packet and error counters for all interfaces.

         Need to clear all counter use clear counters interface all

  • show interface capabilities: Shows the hardware capabilities and supported configurations for an interface.
  • show vlan brief: Displays the status of all VLANs and their associated ports.
  • show logging logfile: Displays system logs which are critical for identifying the cause of interface resets or errors.
  • show udld / show tech-support udld: Used for troubleshooting Unidirectional Link Detection (UDLD) issues.
  • show running-config interface <interface>:Shows the current running configuration applied to a specific interface.
         Reference image


4.Common Feature Commands by Category

     Layer 2 Features

Command

Purpose

feature lacp

Enables Link Aggregation Control Protocol for dynamic port channels

feature vpc

Enables Virtual Port Channel functionality

feature interface-vlan

Enables creation of SVIs for Layer 3 VLAN interfaces

feature lldp

Enables Link Layer Discovery Protocol

feature cdp

Enables Cisco Discovery Protocol

feature span

Enables Switched Port Analyzer (port mirroring)

feature udld

Enables UniDirectional Link Detection

feature stp

Enables Spanning Tree Protocol (though basic STP is often on by default)

      Layer 3 Features

Command

Purpose

feature ospf

Enables OSPF routing protocol

feature eigrp

Enables EIGRP routing protocol

feature isis

Enables IS-IS routing protocol

feature bgp

Enables BGP routing protocol

feature rip

Enables RIP routing protocol

feature static

Enables static routing extensions (usually on by default)

 

 5.Reference