VDC's - Virtual Device Contexts. Means I can split a physical nexus in to logical nexus which are totally isolated. If I want to connect VDC's together from within the same chassis there would be a cable coming out of one port on the nexus belonging to VDC 1 and physically plugging back to the same chassis to a different VDC e.g. VDC 2.
VPC - Virtual Port Channel. Its a means to provide an end host or switch(s) with multiple physical links to from two separate Nexus devices, be it the 7Ks or the 5Ks, that is one virtual link, like port-channel or etherchannel. But is not a stacking technology for Nexus.
VSS - Virtual switching system. This is a great technology whereby two physical chassis like c6500's can form in to one virtual device - this is like a stacking technology, you have one of the chassis active in the control plane, but both are forwarding data plane traffic.
The Cisco ASR 9000 is probably more of a service provider router - very powerful for routing and extremely controlled! OS and command line is a lot different that normal IOS or NXOS.
The Cisco Nexus is more a Data Center or Core network switch where it has a fairly rich feature set to support data center applications with technologies like OTV inbuilt.
Hope this helps.
Please rate useful posts & remember to mark any solved questions as answered. Thank you.
Introduction This article will help you understand the steps on how to
download the UCS licenses from the Cisco Systems website and then
installing it on the UCS. The redacted (blue lines) just covers up
certain numbers for privacy please do not take them...
Introduction This article will help you understand and educate the
customer on how to clear their "expired licenses"
(license-graceperiod-expired) from their UCS-M. If a customer just
purchased a license and needs a step by step guide on how to download
Introduction Prepositioning is a powerful tools on the WAAS platform but
it is not always easy to figure out why your jobs are failing when
trying to retrieve the files.Here is a method that should help you to
figure out the reason why they are not succes...