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Why You’ll Want This Switch, Part 2

February 22, 2008
at 12:00 pm PST

So, if bigger/faster/denser is not the reason to drop a Nexus 7000 in your network, why is a compelling reason?In my last post, I touched on NX-OS, as the foundation for many of the cool things the Cisco Nexus can do now and in the future. One of those areas is operational continuity. We have the component redundancy that’s table stakes in a next-gen platform with redundant power, fans, supervisors and fabric modules, but we wanted to raise the bar in terms of protecting the network services this platform delivers-what we call a zero service disruption architecture. We don’t just want highly available hardware; we want highly available network services, because that’s what really counts.One design decision we made was to loosely couple the control plane and the data plane, so we can do things like in-service software upgrade without disrupting packet forwarding-we can even do firmware upgrades to the I/O modules without disrupting packet forwarding. One of the cooler features on the Cisco Nexus is stateful process restart. With NX-OS, we can re-start individual processes in a way that maintains state data, so, for instance, if you need to restart spanning tree, the system will maintain state data, so you can avoid the resulting chaos of having to re-learn addresses and re-establish the topology. Along those same lines, the Cisco Nexus also has checkpoint/rollback functionality, so if you push out a change that does not work as expected, instead of having to troubleshoot it in real time, you can simply rollback to the previous working config.Finally, from the Department of Attention to Detail, we even short-pinned the fabric modules (i.e. the input pins are shorter than the output pins). Why should you care? Well, in case someone accidently yanks out the wrong fabric module, the input pins will disengage first, to stop receiving new packets, and the fabric module is fast enough to empty before the output pins have disengaged. And the system will automatically adjust to the new fabric capacity and keep humming along.So, there are just a few of my favorite features-things I wish I had when I ran data center networks. For more info, check out this whitepaper: http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9402/ps9512/White_Paper_Continuous_Operations_High_Availability.html

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