Computer Science Computing Systems virtual machine

System Virtual Machine

• Hypothetical machine
• Designed to contain important features of real computers

Network Connections

• Every VM has a vNIC (virtual NIC)
  • Can connect VM to other machines
  • Operates at the data link layer
• Maximum number of vNICs depends on limits imposed by hypervisor
• Networking modes
  • Bridged
    • vNIC accesses physical network using host machine's NIC
    • Obtains own IP address, default gateway, and network mask from DHCP server on physical LAN
    • Appears to other nodes as a regular client/server on the network
  • NAT
    • vNIC relies on host machine to act as NAT device
    • Obtains IP address from host
    • Hypervisor acts as a DHCP server
    • Other nodes on network won't have direct access
      • Must go through host
  • Host-only
    • VMs on one host can exchange data with each other and the host
    • Cannot communicate to nodes outside the host
    • Never receive or transmit data with host's physical NIC