A virtual network f unction is a virtual or software version of a network function.
It runs as a virtual machine on a hypervisor.
Virtual network functions are commonly used for Layer 4 to Layer 7 functions, such as those provided by Load Balancers and Application Delivery Controllers, firewalls, intrusion detection systems and WAN optimisation appliances.
They are not limited to Layer 4 to 7 applications though – they can perform lower level functions through functions provided by routers and switches.
Some examples are Cisco virtual network functions, such as:
- Cisco Cloud Services Router 1000V
- Cisco Cloud Services Platform 2100
- Cisco Integrated Services Virtual Router
- Cisco NextGen Firewall Virtual Appliance
- Cisco Adaptive Security Virtual Firewall