What is VDC-Virtual Device Context , and how to Configure them ? Cisco Nexus 7K

Nexus 7000 series introduced Virtual Device Context or VDC. VDC enables users to divide one Cisco Nexus 7000 switch into 4 different switches, where each switch operates as a stand alone switch. Each unit has dedicated processor, ports, and protocols.

This allows consolidating multiple physical devices into one , still having 4 different switches.

Usually on standard data center environment we will have multiple VLANs and multiple VRFs segregating different types of data. However problem on the switches control plane can cause all those to fail simultaneously.

So following same technology of Hypervisor multiple logical switches can be configured on a single physical switch. Ports can be reallocated between VDCs in a flexible manner.

Using VDCs, we can configure 2 nexus switches to participate in both Core and Aggregation layer instead of having to buy more hardwares.

VDC1 is the default VDC, and has a special role. VDC1 can create other VDCs, allocate resources, all non default VDCs are strictly separated.

VDC Rules of Engagement:

  1. The Cisco NX-OS advanced Services License is required to create, delete or modify VDCs. A grace period exists(120 days), but once it’s over any VDC configuration will be deleted. 
  2. VDCs are created from the Default VDC global config mode. Network-admin role is needed to create, delete or modify VDCs.
  3. Physical and logical resources (ports, memory) are allocated to VDCs from Default VDC. Once done those ports can be configured only from that VDC.

 Configuring VDC on Nexus 7000 switches:

Creating VDC: enter global configuration mode, and just type VDC Name, here we are creating a VDC named RED.

creating and deleting vdc

 

Now that the VDC is created, lets allocate some Interfaces to it. Remember VDC Red is now a stand alone switch. and switches need interfaces right ?

Allocating interfaces:

allocating interface

 

To Verify Interface allocations in VDC do the following command..

show vdc membership

It will show all the VDCs and ports allocated to them. Almost like show vlan command. This has to be done from Default VDC or VDC1. Otherwise it will show only that VDC information, not all.

we can issue  show vdc details to see more details on each vdc.

When a VDC is created, default template is allocated. Which can be shown with following command..

show vdc [vdc Name] resource

Configuring Resource assignment:

resource allocation

 

We can also create resource templates to streamline resource allocations.

Navigating to VDCs:

switchto VDC [vdc name] will take us to the vdc we want to be in.

switchback command , will bring us back to default .

To save the running config of all vdc we should do

copy run start vdc-all

Configuring high availability:

high availability

 

VDC Configuration best practices:

best practice

 

I hope this is enough to understand and configure the VDCs on a nexus 7000 switch. I will talk about troubleshooting VDC issues if when I get a chance.

Have a good day!

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