Specifications

Administration Guide
28 VMware, Inc.
Private Virtual Ethernet Networks (VMnets)
You!can!use!VMnet!connections!for!high‐speed!networking!between!virtual!machines,!
allowing!private,!cost‐effective!connections.!The!isolation!inherent!in!their!design!
makes!them!especially!useful!for!supporting!network!topologies!that!normally!depend!
on!the!use!of!additional!hardware!to!provide!security!and!isolation.
Figure 1-2. Firewall configuration example
In!Figure 1‐2,!an!effective
!firewall!can!be!constructed!by!configuring!one!virtual!
machine!on!an!ESX!Server!system!with!two!virtual!Ethernet!adapters,!one!bound!to!a!
VMnic!(giving!it!a!connection!to!a!physical!network)!and!the!other!bound!to!a!VMnet.!
Other!virtual!machines!would!be!connected!only!to!the!VMnet.!By!
running!filtering!
software!in!the!dual‐homed!virtual!machine,!a!user!can!construct!an!effective!firewall!
without!the!need!for!additional!hardware!and!with!high‐performance!virtual!
networking!between!the!virtual!machines.!
You!can!use!a!similar!approach!with!multitier!applications!(with!the!Web!or!application!
servers!reachable!from!other!systems)
!but!with!the!database!server!connected!only!to!
the!other!tiers.
Virtualization at a Glance
ESX!Server!virtualizes!the!resources!of!the!physical!system!for!use!by!the!virtual!
machines.
Internal
Network
Virtual
Machine
Internal
Network
Virtual
Machine
vmnic0
NIC
Physical NIC
vmnet_1
vmnet_0
Virtual
machine 1
Firewall
Virtual
machine 2
External
Web server
Virtual
machine 3
Firewall
Virtual
machine 4
On internal
network