After consulting with the network team, it is decided that Transport Zones will be configured with
Unicast Replication Mode for a new NSX for vSphere deployment.
Which statement is true regarding the function of the VXLAN Tunnel End Points (VTEPs)?
A.
The VTEPs will send unicast frames to the NSX Controllers when the VTEPs do not have a
MAC address in the MAC table.
B.
The VTEPs will switch to Multicast Replication Mode for those VTEPs to which multicast path
discovery is successful.
C.
The VTEPs will send multicast frames to all other VTEPs in the Transport Zone when the
VTEPs do not have a MAC address in the MAC table.
D.
The VTEPs will send unicast frames to all local VTEPs and remote proxies in the Transport
Zone when the VTEPs do not have a MAC address in the MAC table.
My Guess is D
I guess that A happens first, the controller does not have the MAC either, then D is the way to go.
controllers are used only when you use hybrid mode.
wrong… controllers are used also in unicast so i’ll go for A
I don’t clearly see why A isn’t a valid answer. Controllers are used in either case, but what if the controller doesn’t have the information??? then what?
That’s where I think D is correct.
See this great article: https://telecomoccasionally.wordpress.com/2015/01/11/nsx-for-vsphere-vxlan-control-plane-modes-explained/
To recap:
Host relies on contents of MAC:VTEP table to find destination VTEP.
This table is populated by learning from incoming traffic.
If there’s no entry, LS in Unicast or Hybrid mode will query Controller for the mapping. LS in Multicast mode will not, as Controller isn’t used.
When the destination MAC has no matching entry (and Controller hasn’t replied in Unicast or Hybrid mode), or is a Broadcast or Multicast destination (a.k.a. “BUM”), then host will flood that frame to all other hosts that are members of that VXLAN
Option D is correct ONLY when Controllers don´t have mapping info about other VMs in their MAC/VTEP tables.
Option A is correct because VTEPs always query Controllers with control plane requests (unicast frames)
D.
In unicast mode, a VTEP is designated to be a proxy for traffic originating in other segments. This proxy is known as a UTEP because it uses unicast to replicate traffic within a segment
Source VTEP:
Replicates encapsulated frame to each local VTEP
Replicates encapsulated frame to each local UTEP
D is correct per page 39 of the latest NSX Design Guide walking through UNICAST mode process
Correct Answer should be A, and then B :
1 – ESXi send request to the controller
2 – In case controller doesn’t have MAC address, VTEP floods other VTEP DEPENDING the configuration mode (Unicast,Multicast or Hybrid)