VDC is said to be virtual device context, supported by Cisco NX-OS Software series. VDC helps in partition a single physical device to multiple logical devices which acts as unique and independent switch and has its own configuration and can be managed by separate administrator.
With VDC, We can manage multiple logical switch with in physical device, each VDC has its own unique set of L2 and L3 process, which runs on each of logical switches. We can treat these logical switches or these logical switch behaves same like physical switch which has its own set of L2 and L3 process and configuration running because each logical switch contains its own configuration file stored in NVRAM via VDC name and each logical devices has its own L2 and L3 control plane as we have like in each physical switch.
Following are benefits of VDC:
- Provides Fault isolation, if any fault occurs in any L2 or L3 process, it does not affect any other processes running on another logical switches.
- Provides management Isolation, each logical switches can be treated as individual switch and can be managed separately. It can be accessed by unique individual IP.
- Hardware Isolation, if any hardware resource is allocated to any VDC , it will be part of that VDC till the time , admin can reallocated it to any another VDC.
- Provides separation of data traffic at VDC level
- Provide enhance Security at VDC level.
VDC also virtualize the control plane like L2 tables (MAC tables), L2 Protocols, RIB and Routing protocols.
When any VDC is created, Control plane processes are replicated to all other VDC by NX-OS software. This replication enables VDC administrators use VLAN and VRF independently to those used in other VDCs. In Ethernet VDC, same VLANs numbers can be used across different VDC.
VDC is created on same physical Nexus Switch by using the same Kernel and Infrastructure layer as base.
We will discuss the purpose of using Kernel and infrastructure layer in creation of VDC.
- Cisco NX-OS uses Linux Kernel 2.6 for VDC creation.
- This Linux 2.6 kernel is the base layer over which NX-OS resides and operates
- With the help of this Kernel , Nexus support Multithreading and multitasking
This Infrastructure Layer is nothing but NX-OS software that runs on Kernel.