Which of the following is not a means used by Cisco VIC adapters to communicate?
- by using store-and-forward switching
- by using a bare-metal OS driver
- by using software and a Nexus 1000v
- by using pass-through switching
Of the available choices, Cisco virtual interface card (VIC) adapters do not communicate by using store-and-forward switching. However, switches can be configured to use store-and-forward switching. A switch that uses store-and-forward switching receives the entire frame before forwarding the frame. By receiving the entire frame, the switch can verify that no cyclic redundancy check (CRC) errors are present in the frame; this helps prevent the forwarding of frames with errors. Cisco VIC adapters are hardware interface components that support virtualized network environments. Cisco VICs integrate with virtualized environments to enable the creation of virtual network interface cards (VNICs) in virtual machines (VMs).
Cisco VIC adapters support three communication methods: by using software and a Cisco Nexus 1000v virtual switch, by using pass-through switching, and by using a bare-metal operating system (0S) driver. In other words, traffic between VMs is controlled by the hypervisor, which is the software that enables the virtualization of system hardware. Cisco describes the software-based method of handling traffic by using a Cisco Nexus 1000v virtual switch as Virtual Network Link (VN-Link).
Pass-through switching, which Cisco describes as hardware-based VN-Link, is a faster and more efficient means for Cisco VIC adapters to handle traffic between VMs. Pass-through switching uses application-specific integrated circuit (ASIC) hardware switching, which reduces overhead because the switching occurs in the fabric instead of relying on software. Pass-through switching also enables administrators to apply network policies between VMs in a fashion similar to how traffic policies are applied between traditional physical network devices.
Cisco VIC adapters forward traffic similar to other Cisco Unified Computing System (UCS) adapters when installed in a server that is configured with a single bare-metal OS without virtualization. It is therefore possible to use a Cisco VIC adapter with OS drivers to create static vNICs on a server in a nonvirtualized environment.