Cisco NX-OSConfig1,234 downloads

Cisco NX-OS Base / Day-0 Config

Day-zero configuration for Cisco Nexus switches: hostname, features, users, management interface, NTP, DNS, syslog, and SSH.

↓ example.txt

What is it?

Cisco NX-OS is the operating system running on Nexus data center switches. Unlike IOS, NX-OS uses a modular feature model — protocols and services are not enabled by default, you must explicitly run 'feature ospf', 'feature bgp', 'feature lacp', etc. This reduces the attack surface significantly. NX-OS also has a dedicated management VRF (Virtual Routing and Forwarding) that completely isolates management traffic from production traffic — SSH and syslog travel through 'vrf management' while data plane traffic uses the default VRF.

When to use

·First thing after unboxing any Cisco Nexus switch (5000, 7000, 9000 series)
·Before enabling any other features or connecting to the production network
·During data center build-outs — base config is the foundation for VXLAN EVPN, vPC, and BGP configs
·As part of a ZTP (Zero Touch Provisioning) automation pipeline for day-0 deployment

When NOT to use

·This IS always needed — there is no scenario where skipping the base config is appropriate in production

How it compares

vs Cisco IOS base configIOS has most features enabled by default — you disable them. NX-OS has almost nothing enabled by default — you enable what you need with 'feature' commands. NX-OS is safer out of the box.

vs Arista EOS base configEOS and NX-OS follow similar feature-enable models. EOS uses 'management api http-commands' for eAPI access (like NX-OS's 'feature nxapi'). Both are data-center focused OSes.

Prerequisites

→Console access via terminal emulator (PuTTY, SecureCRT) for initial setup
→Management IP and gateway — mgmt0 interface is the out-of-band management port
→NTP server IPs — NX-OS requires NTP per VRF (use-vrf management for the mgmt0 interface)
→Features to enable: plan which protocols you'll need (ospf, bgp, vpc, lacp, etc.) before deploying

Config Generator

Hostname *

Domain Name

Admin Password *

NX-OS Features to Enable

Management IP (CIDR) *

Management Gateway *

Management VRF

NTP Servers

DNS Server 1

DNS Server 2

Syslog Server

Timezone

MOTD Banner

Verification commands

show version

Verify NX-OS version, uptime, and hardware model

ExpectedShows NX-OS version, chassis type, and module states

show feature

List all available features and which are enabled/disabled

ExpectedShows 'enabled' or 'disabled' for each feature. Verify features you need are enabled.

show ip ssh

Verify SSH is running on the management interface

ExpectedShows SSH version 2 enabled

show ntp status

Verify NTP is synchronized

ExpectedClock is synchronized, reference is your NTP server IP

show interface mgmt0

Verify management interface has the correct IP and is up

ExpectedInterface status should be 'up'. Shows IP address, speed, and counters.

Debug commands

show logging last 50

Show the last 50 syslog messages on the device

Common mistakes & fixes

SymptomCannot SSH after base config — connection refused

Cause'feature ssh' not enabled or RSA key not generated

FixRun 'feature ssh' then 'crypto key generate rsa'. Verify with 'show feature | grep ssh'.

SymptomNTP not synchronizing

CauseNTP server specified without 'use-vrf management', so it tries the default VRF

FixAdd 'use-vrf management' to the NTP server command. Verify reachability: 'ping <ntp-ip> vrf management'.

SymptomSyslog messages not reaching the server

CauseMissing 'use-vrf management' on the logging server command

FixAdd 'use-vrf management' to 'logging server' command. NX-OS management traffic must specify the VRF.

Further learning

Recommended books to go deeper on this topic.

CCNA 200-301 Official Cert Guide Library

Wendell Odom · Cisco Press · Best starting point for Cisco IOS fundamentals — CLI, interfaces, basic routing

Kindle ↗Hardcover ↗

CCNP Enterprise Core ENCOR 350-401 Official Cert Guide

Brad Edgeworth et al. · Cisco Press · For engineers ready to go deeper — routing, switching, security, automation