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NX-OS is a network operating system designed by Cisco Systems for their own Nexus-series Ethernet switches and MDS-series Fibre Channel storage area network switches. NX-OS is designed to support high performance, high reliability server access switches used in the data center. NX-OS evolved from the Cisco MDS operating system, SAN-OS. SAN-OS was originally developed for the MDS line of switches.[1]

It is based on MontaVista Software embedded Linux. It is inter-operable with other Cisco operating systems. It runs on both the Nexus and MDS product lines by Cisco.

NX-OS command-line interface is IOS-like. However, some features need to be enabled explicitly first before configuring.[2]

One of the unique features of NX-OS is ITD (Intelligent Traffic Director).

ITD is a hardware based multi-Tbps Layer 4 load-balancing, traffic steering and clustering solution on Nexus 7000 series of switches. It supports IP-stickiness, resiliency, NAT (EFT), VIP, health monitoring, sophisticated failure handling policies, N+M redundancy, IPv4, IPv6, VRF, weighted load-balancing, bi-directional flow-coherency, and IPSLA probes including DNS. There is no service module or external appliance needed. ITD provides order of magnitude CAPEX and OPEX savings for the customers. ITD is available on Nexus 7000/7700 series in NX-OS 6.2(8) or later. It will also be available on Nexus 5k/6k. ITD is much superior than legacy solutions like PBR, WCCP, ECMP, port-channel, layer-4 load-balancer devices.


Switches running NX-OS[edit]

  • Nexus B22 (HP, Dell, Fujitsu)
  • 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[edit]

  • 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]


4.1, 4.2, 5.0, 5.1, 5.2, 6.0, 6.1, 6.2

See also[edit]

External links[edit]


  1. ^ Cisco NX-OS Software: Business-Critical Cross-Platform Data Center OS
  2. ^ Nexus: Hands on with NX-OS, Part#1
  3. ^ Cisco Product Brocuhure Cisco MDS 9500 Series of Multilayer Directors, visited 18 May 2012
  4. ^ "Cisco Nexus 7000 Series NX-OS Security Configuration Guide, Release 4.1". 
  5. ^ "Cisco NX-OS/IOS Configuration Fundamentals Comparison".