Vsphere spanning-tree issue?

[Pim Scheffers]

Hi,

Our vmware team came to me with a question, they want to hook up a vmware vsphere machine to the network as described in the attached pdf file.

The 2 etherchannels between the 2 6500's are already in place.

Our 2 cisco 6500 switches are not VSS capable and we don't  have Cisco virtual switches, just the standard vswitches in vmware.

When i saw it i could only think about a spanning-tree loop.

So my 2 questions are:

1) Is this possible or will i create a loop with this design which will cause the 2 6500's to recalculate spanning tree for the 4 vlans in question and block a specific port for that vlan? or will the bpdu' s not be sent?

2) What is the recommended design for redundancy without VSS or Cisco's virtual switches?

Thanks

[dominic.caron · Accepted solution]

Hi,

The Vswitch included with Vmware will not cause a loop. If you receive a frame from the uplink, only two thing can occur, it will be forwarded to one of the VM or it will be dropped. The only way you can cause a loop is if you bridge 2 virtual interface inside a virtual server.

You usualy configure portfast on the interface connecting to the ESX server. This will identify the port as an edge port to 802.1w. Lease spanning-tree in place just in case a virtual server is misconfigured.

[Pim Scheffers]

Thanks Dominic.

you were right on.

I actually found this document which helped me explain it. (it's for esx 3 but the concepts should not change much in Vsphere 4)

http://www.vmware.com/files/pdf/vmi_cisco_network_environment.pdf