Configuring switches for VMWare

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Feb 19th, 2008
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Our server team has just come to us with a new VMWare project. They are a little unclear on exactly what we need to configure out switches to work for them. Can anyone with some VMWare experience let me know what needs to be done for the configurations?

We have multiple VLANs in the environment and the different virtual servers will be assigned various IPs according to function. At present, servers are accessible if they are given an IP that is in the same range as the VMWare servers themselves, but not if it's outside of that VLAN.

The physical servers (there are four of them) are all on the same blade in the Catalyst 6509.

Thanks much in advance.

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Scott Cannon Tue, 02/19/2008 - 16:12
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Hi Teresa,

What version of VMware are you running? I've just finished a similar project using ESX 3.52.

You issue defintely sounds like a trunking issue to me.

One hurdle I faced with the VLANing of the hosts is that hosts tag their packets in an 802.1q like manner and you need to run .1q trunks on the physical links between the switch and the vm hosts if either hosts or VMs are on anothying other than the native vlan.




teresawhitlock Wed, 02/20/2008 - 05:32
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Since the server team is handling this, I don't actually know what version and it's far too early for them to be here to ask.

Anything special other than setting up the trunks?

adam.sellhorn Wed, 02/20/2008 - 06:43
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When you install ESX on your blades you can consider them to each be switches from a networking point of view. Any VLAN that you are going to need leave that switch (ESX Server) to your physical infrastructure will need to be trunked to your physical switch port. You or your server team will have configure the virtual switch in Virtual Infrastructure (VI), assuming you are going to use this, for these VLANs to tie your virtual server nics to the physical trunks on the ESX servers. I beleive that VMware still allows for a demo of VI where you can play around with this and get comfortable before you make the investment. They also have great documentation on their site.

teresawhitlock Wed, 02/20/2008 - 07:00
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Please forgive my confusion. Does trunking need to be set up on that port on my Catalyst? Or in the VMWare VI? Or both?

adam.sellhorn Wed, 02/20/2008 - 07:24
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No need to ask for forgiveness regarding your confusion. That is why we are here.

Both physical ports, ESX and Catalyst, will need to be configured for trunking. You will likely configure the ESX port through VI. In your implementation your physical NIC on the Blades will likely just be uplinks from your Catalyst switch to your virtual switch.

The following link will help with the concept.

Scott Cannon Wed, 02/20/2008 - 15:34
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In my scenario I had 2 PHY nics in my ESX server with 2 logical nics on each, each logical nic in a different VLAN. In this scenario I only had to configure trunks on the switch. This is because ESX automatically tags any VLAN traffic going across its PHY nics in dot1q.

Another option you have is to assign physical nics to a single vlan. In another scenario I have here I have4 nics in an ESX server with 2 virtual switches (vSwitch) and 2 nics assigned to each vswitch. There is no VLANing as far as the ESX server is concerned - just 2 seperate physical networks. Each PHY port on the PHY switch is then VLAN'd accordingly.




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