NX-OS is a network operating system for the Nexus-series Ethernet switches and MDS-series Fibre Channel storage area network switches made by Cisco Systems. It evolved from the Cisco operating system SAN-OS, originally developed for its MDS switches.^[1]

It is based on Wind River Linux and is inter-operable with other Cisco operating systems.^{[citation needed]} The command-line interface of NX-OS is similar to that of Cisco IOS.^[2]

Recent NX-OS has both Cisco-style CLI and Bash shell available. On NX-OS 7.0(3)I3, the output from uname with the -a command line argument might look like the text below:

$ uname -a
Linux version 3.4.91-WR5.0.1.13_standard+ (divvenka@sjc-ads-7035) (gcc version 4.6.3 (Wind River Linux Sourcery CodeBench 4.6-60) ) #1 SMP Tue Feb 6 12:43:13 PST 2018

Core features

• System Manager (sysmgr)
• Persistent Storage Service (PSS)
• Message & Transaction Services (MTS)

Additional features

• Fibre Channel and FICON
• FCIP
• FCoE (Nexus 5000/7000 linecards)
• iSCSI
• IPsec
• Scheduling
• NPIV NX Port ID Virtualization
• Inter–VSAN Routing
• VSAN
• Zoning (Hard zoning)
• Callhome
• Cisco Fabric Services (distributed configuration)
• SSH and Telnet
• Storage Media Encryption
• Port Channels
• Cisco Data Mobility Manager
• Fibre Channel Write Acceleration

Switches running NX-OS

• Nexus B22 (HP, Dell, Fujitsu)
• Nexus 9000 series
• Nexus 7700 series
• Nexus 7000 series
• Nexus 6000 series
• Nexus 5000 series
• Nexus 4000 (for IBM BladeCenter)
• Nexus 2000 series
• Nexus 3000
• Nexus 1000V
• MDS 9700 FC Directors
• MDS 9500 FC Directors^[3]
• MDS 9250i FC Switch
• MDS 9222i FC Switch
• MDS 9100 FC Switches

Differences between IOS and NX-OS

• NX-OS does not support the login command to switch users.
• NX-OS does not distinguish between standard or extended access lists, all lists are named and "extended" in functionality.^[4]
• NX-OS did not support scp server prior to 5.1(1) release.
• In NX-OS, there is no "write" command to save the configuration like on IOS (one uses the "copy" command, instead). Instead, command aliases can be created to provide the "write" command.
• When accessing NX-OS, users authenticate directly to their assigned privilege level.
• SSH server is enabled while Telnet server is disabled by default in NX-OS.^[5]

Releases

4.1, 4.2, 5.0, 5.1, 5.2, 6.0, 6.1, 6.2, 7.0, 9.2, 9.3, 10.1