Cisco Nexus 7000 - Virtual Device Contexts

One aspect why Nexus 7000 is very different with Catalyst or MDS families, is that Nexus designed with Virtualization from the start.

Virtualization in Nexus is called VDC (Virtual Device Contexts), its hardware level virtualization, very similar with hypervisor based virtualization. VDC is the 'virtual machine' and it is representing one unit of virtualized Nexus 7000 - it has its own routing protocol, switching process, configuration, administrator, physical ports, hardware data plane and management plane.



The virtualization concept in networking device is not new. Cisco IOS XR that run on Cisco CRS-1 and GSR also support similar virtualization. All of them gives the following benefits :

• VDC allows the user to use their own virtual context safely, without impacting other user (on different VDC)
• Each VDC can have different administrator. This may be not common, but sometime is necessary for specific requirement, i.e. for testing or training purpose. The administrator from one VDC will be completely separated with the others, so he/she can not cause any damage to different VDC
  
• Allow easier migration or consolidation from old network to new network with different department or policy
• Very useful for training/testing purpose, since we could just define some VDC for that purpose to avoid buying new/used equipment

In the service provider area, VDC concept also very powerful. With VDC we could create a fully automated virtual data center easily, and have it assigned to different customers.

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