vmware796
Contributor
Contributor

VM to VM communication on the same host

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I have poured over the network docs and some other threads but I cant seem to find how VM to VM communication works on the same host.

If I have 2 VM's on the same host in different subnets connected to the same vswitch can they talk directly? or do packets have to traverse the physical network and back in? I am sure there must be a way for vm's on the same host,vswitch to talk directly, can someone please give me some tips on how this works and what are any limitations.

Thanks

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khughes
Virtuoso
Virtuoso

If it's plugged into the same vSwitch it is just like plugging two servers into the same physical switch, on different subnets, it's not going to work. There has to be some sort of firewall / routing to have those two systems talk accross different networks.

-- Kyle

"RParker wrote: I guess I was wrong, everything CAN be virtualized "

-- Kyle "RParker wrote: I guess I was wrong, everything CAN be virtualized "

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khughes
Virtuoso
Virtuoso

If it's plugged into the same vSwitch it is just like plugging two servers into the same physical switch, on different subnets, it's not going to work. There has to be some sort of firewall / routing to have those two systems talk accross different networks.

-- Kyle

"RParker wrote: I guess I was wrong, everything CAN be virtualized "

-- Kyle "RParker wrote: I guess I was wrong, everything CAN be virtualized "
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vmware796
Contributor
Contributor

thanks, I guess I was trying to assume that a vswitch somehow works differently than a normal switch. So, I would need to modify the network design to have things on the same subnet for that to work.

Appreciate the help

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vmroyale
Immortal
Immortal

Hello and welcome to the forums.

If you can, check out Ken Cline's excellent "[The Great vSwitch Debate|http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-1/]" as it will answer this and much more.

Good Luck!

Brian Atkinson | vExpert | VMTN Moderator | Author of "VCP5-DCV VMware Certified Professional-Data Center Virtualization on vSphere 5.5 Study Guide: VCP-550" | @vmroyale | http://vmroyale.com
MattG
Expert
Expert

You could also look into getting a router appliance and use it to do the routing without having to leave the server.

-MattG

If you find this information useful, please award points for "correct" or "helpful".

-MattG If you find this information useful, please award points for "correct" or "helpful".
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vmware796
Contributor
Contributor

can I also ask is there any performance hit for vm to vm communication ?

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MattG
Expert
Expert

It should be faster as it is all in memory

-MattG

-MattG If you find this information useful, please award points for "correct" or "helpful".