vSwitch <> NIC mapping ?

[S__Cola]

Hello,

I hope this msg board is the good place to ask this question. Excuse me if it's not. I'd like to know how works the mapping between vSwitches and physical interfaces ? Is the mapping always up ? Let me explain myself :

When on of my VM "heavily" uses the network, everything works fine. But, if I stop sending datas for, let's say, about 1 hour, the first connection has a 5-10 seconds delay. After that everything works smoothly again.

I know this kind of behavior exists for components like Firewalls (after X hours, the port between two servers is closed and if it needs to be opened again, the full authentication process is done, causing a 1-2 seconds delay). Does anyone experiment the same kind of problem ?

Thanks a lot.

[esiebert7625]

Physical NIC's on vSwitches are always on and available, they do not go idle after periods of inactivity. Most VM's are always generating network traffic even if it is a small amount. When you say your connection has a delay what type of connection is it? If you ping the VM's during that time do you show any time outs?

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Thanks, Eric

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[S__Cola]

Thank you for your answer. The network schema is the following :

Physical1 -- VM -- Physical2

From Physical1, I launch a small app checking if Physical2 is up & running (some kind of ping, but with a little bit more traffic). So, the traffic goes : Physical1 - VM - Physical2 - VM - Physical1.

After the first check, there's no more delay. When I use a physical machine instead of the VM, there's no delay.

[esiebert7625]

When you say 'Physical1' and 'Physical2' are you meaning your physical NIC's or a Physical server?If you post the output to the following commands it would help us understand yoru configuration.

esxcfg-vswitch -l

esxcfg-nics -l

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[S__Cola]

Yes, excuse me, Physical1 and 2 are physical servers

[esiebert7625]

So are you using the VM as a network router that all traffic needs to go through from Physical1 to get to Physical2 or is it some type of a passthrough server for some application that you are using?

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[S__Cola]

The second option. The VM acts like a server, provinding services for Physical1 (who acts like a "client").

When Physical1 connects to VM, the virtual machine checks all the other connected servers (in this case, Physical2, but in facts, there could ben a Physical3, Physical4, ....), displays them in a list and allow Physical1 to "check if they're up & running" via a GUI. When you click on the button, Physical1 sends few bytes to VM who routes it to the selected server.

[esiebert7625]

So the big question is whether the VM is losing network connectivity completely or is it a TCP connection or application problem. I would start with seeing if the VM can be pinged without dropping any packets when the problem occurs. If it can be pinged without problem them it sounds like an application or TCP setting that may be causing the problem.

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Thanks, Eric

Visit my website:

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