Tag Archives: Nexus-OS

What Is Nexus-OS and How Does it Compare?

Nexus OS is a Cisco Systems network operating system. They created it for their personal Ethernet switches as well as their MDS fiber channel storage network switches. Nexus OS, also known as NX-OS, has been created specifically for high reliability, high performance services in a data center. Its predecessor was the SAN-OS, also by Sisco, which was designed solely for the MDS switches.

The basis of NX-OS is Monta Vista Software, which is embedded within Linux. It can be used, therefore, with all other Cisco operating systems as well, mainly the MDS and the Nexus product lines. The command line interface of NX-OS is very similar to IOS. However, it has a number of different features that must be specifically enabled first. The most unique feature is the ITD (Intelligent Traffic Director).

Cisco and NX-OS Header.fw__0

What Is ITD?

Essentially, it is a multi-Tbps layer solution on the switches that come with Nexus 7000. This includes resiliency, IP stickiness, NAT (EFT), health monitoring, VIP, N+M Redundancy, sophisticated failure handling policies, IPv6, IPv4, weight load-balancing, VRF, IPSLA probers (including DNS) and bi-directional flow coherency. Best of all, it doesn’t need an external appliance or service module. ITD can be used on all the Nexus 7000 and 7700 series that run NX-OS6.2(8) or above. It is also believed that it will soon be made available to work on Nexus 5k and 6k. ITD is the most superior solution out there at present, particularly compared to things like WCCP, PBR, layer 4 load balancer devices, port channel or ECMP.

Comparison between Cisco NX-OS and Cisco IOS

A lot of people already know the CLI (Command Line Interface) for Cisco IOS. The NX-OS model is actually very similar to that. However, Cisco has implemented a number of key differences to be aware of. These include:

  • You go directly to EXEC mode when you login in NX-OS.
  • You have more control over the system through the setup utility.
  • The license model is feature based. This means you may need an Advanced or Enterprise Services license.
  • You can test the system for 120 days before having to purchase a license. All information will be removed after that period, however.
  • The configuration command is far more extensive.
  • Ethernet is the label for the configuration. This means you don’t see speed designations as these are learned dynamically.
  • You can use VDC (virtual device contexts), which is actually what you go to by default the first time you log in.
  • SSHv2 is also enabled by default, Telnet is disabled.
  • The login for the administrator is always ‘admin’, a password has to be set when you first login.

There are a number of other key differences, but most users agree that the new NX-OS is far superior than IOS. It is more user friendly, allows for far greater configuration and is believed to be safer as well. Cisco is known for their quality programming options and this new NX-OS is nothing new as far as that is concerned.