Specifications

VMware, Inc. 313
Chapter 11 Networking
or!of!different!virtual!machines)!having!the!same!predetermined!generated!MAC!
addresses!and!your!virtual!machines!will!start!up.!The!guest!OS!must!detect!these!
duplicate!MAC!addresses.!Ensure!that!on!your!LAN,!your!predetermined!addresses!do!
not!conflict!with!each!other!and!do!not!conflict!with!those!that!ESX!Server
!has!
generated.
Setting MAC Addresses Manually
To!avoid!possible!MAC!address!conflicts!between!virtual!machines,!system!
administrators!can!assign!the!MAC!addresses!manually.!VMware!uses!a!different!OUI!
for!manually!generated!addresses:!00:50:56.!The!MAC!address!range!is!
00:50:56:00:00:00‐00:50:56:3F:FF:FF.!
Set!the!addresses!by!adding!the!following!line!to!a!virtual!machine’s!configuration!file:!
ethernet<number>.address = 00:50:56:XX:YY:ZZ
where!<number>!refers!to!the!number!of!the!Ethernet!adapter,!XX!is!a!valid!hex!number!
between!00!and!3F,!and!YY!and!ZZ!are!valid!hex!numbers!between!00!and!FF.!The!value!
for!XX!must!not!be!greater!than!3F!to!avoid!conflict!with!MAC!addresses!that!are!
generated
!by!the!VMware!Workstation!and!VMware!GSX!Server!products.!
The!maximum!value!for!a!manually!generated!MAC!address!is!
ethernet<number>.address = 00:50:56:3F:FF:FF
You!must!also!set!the!option!in!a!virtual!machine’s!configuration!file:
ethernet<number>.addressType="static"
VMware!ESX!Server!virtual!machines!do!not!support!arbitrary!MAC!addresses,!so!the!
above!format!must!be!used.!As!long!as!you!choose!XX:YY:ZZ!uniquely!among!your!
hard‐coded!addresses,!conflicts!between!the!automatically!assigned!MAC!addresses!
and!the!manually!assigned!ones!should!never!occur.!
Using MAC Addresses
Familiarize!yourself!with!MAC!addresses!by!setting!the!MAC!address!statically!and!
removing!the!virtual!machine!configuration!file!options!ethernet<number>.address,!
ethernet<number>.addressType,!and!
ethernet<number>.generatedAddressOffset.!Verify!that!the!virtual!machine!is!
assigned!a!generated!MAC!address.!
VMware!cannot!guarantee!that!a!host!stays!within!a!specific!MAC!address!range.!
However,!VMware!guarantees
!that!the!MAC!address!never!conflicts!with!any!physical!
host!by!using!our!OUIs!(00:0C:29!and!00:50:56),!which!are!unique!to!virtual!machines.