I ran into a recent issue with a customer who was having problems getting VLANs to work as expected with ESX. The basic scenario was that ESX would refuse to work properly with a VLAN that was marked as the native (or untagged) VLAN. This was causing no end of grief for this customer.
I’ve discussed VLANs extensively—first with this blog post, then again here, and again in this SearchVMware.com tip—so I was confident that I could help the customer resolve this issue. Granted, the customer was using Nortel switches, with which I am completely unfamiliar, but a switch is a switch, right?
Not quite. While the configuration seemed correct in all ways, it turns out there is a checkbox somewhere labeled “untag-default-vlan”. If this box is not checked, then the default VLAN gets tagged. Since ESX wasn’t configured with a VLAN tag, then it doesn’t see the network traffic. Once that box gets checked, then the default (or native) VLAN doesn’t get tagged and will be properly recognized by an ESX port group without a VLAN tag configured.
So, if you’re using Nortel switches and having problems with VLANs, double-check this setting.
Tags: ESX, Networking, Virtualization, VLAN, VMware
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Tuesday, June 24, 2008 at 9:28 am
Aleksander Zawisza
If you’re using the CLI on a 55xx switch, you can ensure that the VLAN connecting to the VMware box is untagged by setting the port to “untagAll”. The command is:
vlan ports tagging untagAll
If you have multiple VLANs on the port and you want the default VLAN (called PVID) to be untagged you do:
vlan ports tagging untagPvidOnly
To set the default VLAN on a port, you do:
vlan ports <port(s)> pvid <vlanID>
Here’s a user guide describing in detail how to set up a resilient network configuration for VMware ESX using Nortel’s SMLT:
http://support.nortel.com/go/main.jsp?cscat=DOCDETAIL&id=678681&poid=14761
Wednesday, June 25, 2008 at 2:50 am
Duncan
I ran into this exact same problem about a year ago. It drove me crazy, especially because I’m no networking guy… But in the end someone solved it.
Monday, June 30, 2008 at 4:26 pm
Jason
Hello, anyone with Nortels I would love to know this. On our 3510 which is just like the 5510 but no stacking Intel cards always show asymmetrical flow control even though they can do symmetrical (send and receive pause frames)
Broadcoms show symmetrical
Anyone else see this at his/her site?