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Introduction to Virtual Device Context- VDC in Nexus Environment

December 31, 2018 ,
Today I am going to talk about the virtual feature in the Cisco Nexus devices called as VDC. VDC stands for Virtual Device Context. With the help of VDC we can convert a single physical Nexus device or chassis into various virtual devices or chassis and that depends upon the SUP engine we are using in the device.

Keep in mind that VDC feature is not available in any of the Nexus device below 7K. So now we have the question like how many VDCs we can create in a single Nexus Chassis.

Look at the below picture, you are going to replace Core and Distribution physical switches with the a single Nexus Switch where we create two different VDC for Core and Aggregation layer. The picture defines the right way for your 3 layer architecture in the Datacenter environment.

Hope picture and the below mentioned description will help you guys to understand the concept of the VDC in the datacenter environment.

Fig 1.1- VDC Topology

How many VDC, we can create ?
Well VDC depends upon the SUP engine we are using. Like if we are using SUP 1, we can create maximum of 3 VDCs, if we are using SUP 2, we can create maximum of 4 VDCs and at last if we are using SUP2e, we will have 9 VDCs within the single physical chassis.

  • SUP 1: Maximum of 3 VDCs
  • SUP 2: Maximum of 4 VDCs
  • SUP2e: Maximum of 9 VDCs
Summary of VDC ?
VDCs in the Cisco NX-OS Software platform extend virtualization support to enable true device virtualization. Virtualization of the physical switch offers a number of operational benefits such as greater fault isolation, leading to improved availability. Furthermore, traffic isolation within the confines of a VDC leads to greater security for user data. Numerous switch contexts within a physical switch can help scale physical switch resources across multiple logical groups within an organisation.

What kind of VDCs we can create in a single chassis?
Well If i take an example where i can have scenario of 4 VDCs. I can create the following VDCs.
  • Admin VDC
  • Core VDC
  • Distribution VDC
  • OTV VDC

After you create a VDC, you can change the interface allocation, VDC resource limits, and the single-supervisor and dual-supervisor high availability (HA) policies. You can also save the running configuration of all VDCs on the physical device to the startup configuration.

Below is the basic example to create and check the VDC with allocated ports to the F2e card

NDNA_N7K(config)# vdc Core
NDNA_N7K(config-vdc)# do show vdc
NDNA_N7K(config-vdc)# allocate interface ethernet 0/1 - 4
NDNA_N7K(config-vdc)# limit-resource module-type f2e
NDNA_N7K(config-vdc)# allocate interface ethernet 0/1 - 4
NDNA_N7K(config-vdc)# do show vdc membership module
NDNA_N7K# show running-config vdc all
NDNA_N7K# switchto vdc Core

We will further discuss on the cards interoperate with each other like M and F cards with in the same VDC.