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Chapter 15 Advanced Virtual Networking
ThehostcomputerhasahostvirtualadapterontheNATnetworkidenticaltothehost
virtualadapteronthehost‐onlynetwork.Thisadapterallowsthehostandthevirtual
machinestocommunicatewitheachotherforsuchpurposesasfilesharing.TheNAT
deviceneverforwardstrafficfromthehostvirtualadapter
.
How the NAT Device Uses the VMnet8 Virtual Switch
TheNATdeviceisconnectedtotheVMnet8virtualswitch.Virtualmachinesconnected
totheNATnetworkalsousetheVMnet8virtualswitch.
TheNATdevicewaitsforpacketscomingfromvirtualmachinesontheVMnet8virtual
network.Whenapacketarrives,theNATdevicetranslatestheaddressofthevirtual
mach
inetotheaddressofthehostbeforeforwarding
thepackettotheexternal
network.Whendataarrivesfromtheexternalnetworkforthevirtualmachineonthe
privatenetwork,theNATdevicereceivesthedata,replacesthenetworkaddresswith
theaddressofthevirtualmachineandforwardsthedatatothevi
rtualma
chineonthe
virtualnetwork.Thistranslationoccursautomaticallyandrequiresminimal
configurationontheguestandthehost.
DHCP on the NAT Network
Tomakenetworkingconfigurationeasy,aDHCPserverisinstalledwhenyouinstall
Workstation.VirtualmachinesrunningonthenetworkwiththeNATdevicecansend
outDHCPrequeststodynamicallyobtaintheirIPaddresses.
TheDHCPserverontheNATnetwork,whichisalsousedinhost‐onlynetworking
configurations,dy
namicallyallocatesIPaddressesintherangeof<net>.128through
<net>.254,where<net>isthenetworknumberassignedtoyourNATnetwork.
WorkstationalwaysusesaClassCaddressforNATnetworks.IPaddresses<net>.3
through<net>.127canbeusedforstaticIPaddresses.IPaddress<net>.1isreser
ved
forthe hostadapterand<net>.2isreservedfortheNATdevice.Formoreinformation,
see“DHCPConventionsforAssigningIPAddresses”onpage 305.
InadditiontotheIPaddress,theDHCPserverontheNATnetworksendsout
configurationinformationthatenablesthevirtualmachinetooperate.Thisinformation
in
clud
esthedefaultgatewayandtheDNSserver.IntheDHCPresponse,theNAT
deviceinstructsthevirtualmachinetousetheIPaddress<net>.2asthedefault
gateway andDNSserver.ThisroutingcausesallIPpacketsdestinedfortheexternal
networkandDNSrequeststobeforwardedtoth
eNATde
vice.
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