How to keep vMotioned VMs in the same Subnet

How to keep vMotioned  VMs in the same Subnet

In the case of we have ESX hosts in the same cluster, I believe VMs can be vMotioned within the CLuster. Now if VMs are in different subnets, will this be a problem when they get vMotioned? if so then how to prevent that ?

Thank you
jskfanAsked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
If I understand you, the Network Label has meaning just to the Vmware Administrator not to Vmware system per se.

Correct it's up to the human, to ensure the network label actually ,matches the network!


If I understand you, the Network Label has meaning just to the Vmware Administrator not to Vmware system per se.

Correct if vMotion is setup correctly between hosts, and the preqs are met, you can always vMotion a VM.

Whether the VM has correct networking on the host it's vMotion to, is another question!
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timgreen7077Exchange EngineerCommented:
if the VMs can't communicate with the other subnet then they will not move anyway. also the actual VM doesn't change subnets but it may vmotion to a host in a different subnet. the only way the vm will vmotion is if it can communicate with the other subnet but if it can't then it will not vmotion. as long as vlan tags are in place and your network can ping across subnets you will be fine.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
In the case of we have ESX hosts in the same cluster, I believe VMs can be vMotioned within the CLuster. Now if VMs are in different subnets, will this be a problem when they get vMotioned? if so then how to prevent that ?

no problems.

All your hosts should have indentical networking, otherwise when VMs are moved to new hosts networking will fail!

Ensure all hosts have identical networking! and Network Labels!
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jskfanAuthor Commented:
Assuming there is no Vlan tagging, just Network Labels.
So if a VM is in a specific subnet will not vmotion to a different ESX host within a cluster, unless there is a similar subnet in a different ESX host within that same cluster ?
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jskfanAuthor Commented:
Also if there are 2 ESX hosts that have the same subnet but they are in 2 different Clusters, would the VMs from those same subnet be able to vMotion, or they have to be in the same cluster. I believe VM vMotion, by rule, cannot be vMotioned outside of the Cluster.

Thanks
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
vCenter Server/ESXi is dumb.

All it does is check to see if the same Network Label exists on a host to vMotion to.... it does not check if that network label is the correct network subnet for that VM.

So if your networks are not indentical or correct per host, then vMotion will still function always, but VM will fail network connectivity.
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jskfanAuthor Commented:

So if your networks are not indentical or correct per host, then vMotion will still function always, but VM will fail network connectivity.


If I understand you, the Network Label has meaning just to the Vmware Administrator not to Vmware system per se.
I mean as long as Vlan Tagging is not done properly, the VM can be vmotioned regardless whether its IP address is not matching the Subnet where it should be. then the VM connectivity to outside will fail.
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jskfanAuthor Commented:
Thanks Andrew.

Most of Vmware Books I have seen they do not have good diagrams with explanation of Storage and Network Design for Vmware, they just use confusing Verbiage

Do you know of any Book or Documentation that use Diagrams for Vmware  storage and Network design with clear explanation ?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
That's because it's not really VMware ESXi, vCenter.

Network Design, Networks, Storage, Storage Design are different disciplines used by ESXi!

I'll check my references.... and post back....

I learnt from following Cisco materials.
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jskfanAuthor Commented:
I learnt from following Cisco materials.
which ones ?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
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jskfanAuthor Commented:
AH ..OK .. I thought You had Docs regarding Networking in Vmware.
It is ok
Thanks
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jskfanAuthor Commented:
Thank you
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
There is very little about Networking in VMware, other than what is already provided in the docs, because VMware assumes, you have a Network Engineer, and Storage Engineers....otherwise as a VMware Admin, you need to swat up yourself!
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