Virtualization has become a critical component in most enterprise networks because of modern demands in IT, including increasing efficiency while reducing capital and operational costs. Virtualization is a critical component of the Cisco enterprise network architecture.
Virtualization can represent a variety of technologies, including extracting the logical components from hardware or networks and implementing them into a virtual environment. Some of the advantages of virtualization include the following:
- Flexibility in managing system resources
- Better use of computing resources
- Consolidating low-performance devices into high-performance devices
- Providing flexible security policies
Some of the drivers behind implementing a virtualized environment are as follows:
- The need to reduce the number of physical devices that perform individual tasks
- The need to reduce operational costs
- The need to increase productivity
- The need for flexible connectivity
- The need to eliminate underutilized hardware
Virtualization can be implemented at both the network and the device level. Network virtualization involves the creation of network partitions that run on the physical infrastructure, with each logical partition acting as an independent network. Network virtualization can include VLANs, VSANs, VPNs, and VRFs (Virtual Routing and Forwarding).
On the other hand, device virtualization allows logical devices to run independently of each other on the single physical machine. Virtual hardware devices are created in software and have the same functionality as real hardware devices. The possibility of combining multiple physical devices into a single logical unit also exists.
The Cisco enterprise network architecture contains multiple forms of network and device virtualization, such as the following:
- Virtual machines
- Virtual switches
- Virtual local area networks
- Virtual private networks
- Virtual storage area networks
- Virtual switching systems
- Virtual routing and forwarding
- Virtual port channels
- Virtual device contexts
Device contexts allow the partitioning of a single partition into multiple virtual devices called contexts. A context acts as an independent device with its own set of policies. The majority of features implemented on the real device are also functional on the virtual context. Some of the devices in the Cisco portfolio that support virtual contexts include the following:
- Cisco ASA
- Cisco ACE
- Cisco IPS
- Cisco Nexus series
Server virtualization allows the server’s resources to be extracted in order to offer flexibility and usage optimization in the infrastructure. The result is that data center applications are no longer tied to specific hardware resources, so the applications are unaware of the underlying hardware. Server virtualization solutions are produced by companies such as VMware (ESX), Microsoft (Hyper-V), and Citrix (XenServer).
The network virtualization design process must take into consideration the preservation of high availability, scalability, and security in the data center blocks. Access control issues must be considered in order to ensure legitimate user access and protection from external threats. Proper path isolation ensures that users and devices are mapped to the correct secure set of resources by creating independent logical traffic paths over a shared physical infrastructure.