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Table Of Contents
VMware Server User’s Guide
234 VMware, Inc.
Maintaining and Changing the MAC Address of a Virtual
Machine
Whenavirtualmachineispoweredon,VMwareServerassignseachofitsvirtual
networkadaptersanEthernetmediaaccesscontrol(MAC)address.AMACaddressis
theuniqueaddressassignedtoeachEthernetnetworkdevice.
ThesoftwareguaranteesthatvirtualmachinesareassigneduniqueMACaddresses
withinagivenhost
system.ThevirtualmachineisassignedthesameMACaddress
everytimeitispoweredonifbothofthefollowingconditionsaretrue:
Thevirtualmachineisnotmoved.Thatis,thepathandfilenameforthevirtual
machine’sconfiguration(.vmx)fileremainthesame.
Nochangesaremadetocertainsettingsintheconfigurationfile.
However,VMwareServercannotguaranteethatitwillautomaticallyassignunique
MACaddressesforvirtualmachinesthatrunonmultiplehostsystems.
Avoiding MAC Address Changes
ToavoidchangesintheMACaddressautomaticallyassignedtoavirtualmachine,do
notmovethevirtualmachine’sconfigurationfile.Movingittoadifferenthost
computerorevenmovingittoadifferentlocationonthesamehostcomputerchanges
theMACaddress.
Alsodonotchangecertainsettings
inthevirtualmachine’sconfigurationfile.Ifyou
neveredittheconfigurationfilebyhandanddonotremovethevirtualnetwork
adapter,thesesettingsremainuntouched.Ifyoudoedittheconfigurationfilebyhand,
donotremoveorchangethefollowingoptions:
ethernet[n].generatedAddress
ethernet[n].addressType
ethernet[n].generatedAddressOffset
uuid.location
uuid.bios
ethernet[n].present
Intheseoptions, ethernet[n] isthenumberofthevirtualnetworkadapter,for
exampleethernet0.
NOTETopreserveavirtualnetworkadaptersMACaddress,youalsomustbecareful
nottoremovetheadapter.Ifyouremovetheadapterbutlaterrecreateit,theadapter
mightreceiveadifferentMACaddress.