technobuddha
Contributor
Contributor

1 vm, 2 nics, weird behavior

Hi all,

Picture of setup is below.

I have a few VM's that will have 2 nics configured.

1 nic will be associated with vSwitch0,

2nd nic will be associated on its own, with vSwitch1

I am trying to have 1 nic for all backups, and 1 nic for file copying, etc.

I am having difficulties trying to understand why vsphere 5.0 would act this way.

1 nic = vmnic1 = 192.168.0.11

2nd nic = vmnic3 = 192.168.0.22

I decide to do a smb copy with the first nic (.11) via 1 computer

then do another smb copy with the 2nd nic (.22) via another computer.

You would think that the the first computer would grab the data from vmnic1, (.11)

and the 2nd computer would grab the data from vmnic3, (.22)

NOPE!

for some reason, vsphere would have both copies coming from vmnic3!!!

How do I know this?

I look at the performance, and I can see data going out via vmnic3 only!

anyone know why this is the case, and how to solve it?

I really don't want to have to do a seperate vlan for vmnic3...

Picture 19.png

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9 Replies
weinstein5
Immortal
Immortal

Typically it is the VMs Operating System that selects the NIC for transport and the vmkernel has no influence on that decision - How are you specifying which virtual NIC the traffic is to go out? Have you tried placing the two NICs on different network segments?

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technobuddha
Contributor
Contributor

Hello weinstein5,

and thanks for your time!

I have the 2 nics assigned IP addresses via Windows 2003 server.

I have in vsphere 5, (see the pic) assigned 2 of the nics to different switches, but both in the same IP range.

that's why everything seems so strange!

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weinstein5
Immortal
Immortal

I have forgotten how Windows 2003 selects the NIC to use but since both NICs are on the same network segment it can use the either NIC - I believe you can either fix the route or place each NIC on a seperate network segment -

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technobuddha
Contributor
Contributor

what do you mean by "either fix the route"?

so your saying that its not vsphere that's the issue, but windows 2003?

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weinstein5
Immortal
Immortal

Yes its definitely a windows 2003 issue - since both NICs are on the same subnet traffic can go out either nic -doing a quick google search it seems like there are issues with having NICs on the same subnet -

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technobuddha
Contributor
Contributor

*sigh* ok, thanks for your info.

i guess i'll have to try and find an answer,

or do a seperate vlan

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RogerSween
Contributor
Contributor

You have the right idea. it will have to be split into VLANS to segment the traffic

Try this...

go into hosts and clusters/networking and properties

edit  the vswitch, team the nics based on IP hash, link status only yes to notify and fall back and click ok

In your network, on your physical switch, create a vlan where the back up device is located. In your case, I think it would be 192.168.0.22

Then back in vSwitch0 properties, click add and create a virtual machine network. Give it a name and the VLAN id

Then set nic teaming team the nics based on IP hash, link status only. Include the NICs that will be used for your backup.

See if that works.

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siglert
Enthusiast
Enthusiast

So hjere an easy fix for you.   Create different portgroups within the vSwitch (just named differently) and then assign 1 NIC as the primary and the rest as alternates in each port group.  Then when you power on your VM it will get assigned the NIC you want and the rest will just be there as backups.  Therefore you can utilize all NICS at the same time.

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weinstein5
Immortal
Immortal

Nice solution - 

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