traffic flow between vms

[Dragomir]

If I had 2 vms on the same blade in a b200 M3 on the same vswitch, is the traffic communication between the 2 vms strictly inside the m3 server?

what about if I had one vms on one b200m3 and another vm on another b200m3?

same chassis and the chassis is connected to the FI

Will the traffic between the VMs go stay on the FI or will it go up to the core switch?

[Walter Dey]

Traffic between VM's on the same ESXi are switched locally.

Traffic between VM's which are on the same vlan, but different ESXi hosts.

It depends on the VM loadbalancing algorithm on the vswitch; the default one (originating port id) distributes the VM across the 2 uplinks.

Therefore the chances are that the outgoing traffic is on UCS fabric A, and the incoming traffic on UCS fabric B. Assuming Ethernet end host mode, it means although same vlan, traffic has to exit and then reenter the UCS domain.

If outgoing and incoming traffic are both on fabric A resp B, L2 (Ethernet) switching is done on the UCS FI.

[Dragomir]

yes its host mode. 

so if VM1 is on blade1 and VM2 is on Blade2 and both on same vlan

Will traffic stay within FI or will it go up northbound to core?

and if

VM1 is on blade1 and VM2 is on blade2 but on different vlans, traffic will need to hit the core gateway correct?

[Walter Dey · Accepted solution]

so if VM1 is on blade1 and VM2 is on Blade2 and both on same vlan
Will traffic stay within FI or will it go up northbound to core?

Both is possible ! as I said above: if ingress and egress are on Fabric A resp B, it's FI switched.

However, it could also be ingress on A, egress on B or vice versa, and then has to go Northbound (and getting L2 switched)

and if

 VM1 is on blade1 and VM2 is on blade2 but on different vlans, traffic will need to hit the core gateway correct?

yes !

[Dragomir]

Thanks Walter. That helps.