If you are like me and build and destroy things constantly or just like doing things in ways you probably are not supposed to here is a quick tip.
I was destroying a vCD environment the other day but I wanted to save some templates I created with vCD. Instead of exporting and re-importing or using some intelligent method. I used vCenter to clone the VM to another place. While I was using this machine I cloned it off a few times for some tests.
Then I noticed some network wackiness. A ping would work for a a little while then go away and come back. First thought was I messed something up in the networking on these new hosts. After searching and searching and checking for switching loops. I finally found the machine had a manually coded MAC address. So I had 5 VM’s on the network with the same MAC address. This obviously caused some issues.
To fix it I migrated the machines to VMXNET3, and removed the old NIC because I needed to do that anyway. You could also change the MAC back to automatic. I would guess you would need to powerdown for this, but I didn’t test this out yet.
Ironically enough I ran into this issue with Virtual PC when we were first getting our VMs off the ground for development work. We had all used a cloned version of my VPC and the MAC was hard coded there. Most of the time we didn’t use our VMs simultaneously, until that one day when the VM was going wacky because the router kept throwing the packets to the two different machines at different times 8^D
I can see where you’d want to potentially hard code an IP address, but wouldn’t it be smarter just to always dynamically generate a MAC?