1) Do I have to use the same VLAN for VXLAN on OLD_CLUSTER and NEW_CLUSTER ? This by keeping in mind that, physically, all hosts are connected to the same, trunked, layer2 network segment. I guess it has to be the same VLAN since all related VM's within vcloud will be connected to the same VXLAN network pool ?
From your explanation what i understood is you have a mix of Traditional Storage and VSAN which is absolutely fine and i hope vsan is not stretched in this case ? Does VCD use both traditional storage cluster and VSAN cluster ? I cannot really comment whether you should same VLAN for old and new cluster. If your Org-vdc is spanned across multiple cluster(OLD+NEW) and VM's on both the cluster need access to same external network using one of the network connection(VAPP,Routed,Direct etc) you certainly need the same VLAN or you can use a new VLAN and create external network. Also if we have unique org-vdc to cluster mapping they can still share same external network . Below diagram is just a sample one - and we have a External network . All we need is add the respective VLAN numbers in vCD external network configuration
2) What about those logical switches in NSX ? Is it required with VXLAN ? I saw that enabling VXLAN does those things :
-Adjusting the MTU of the selected DVS switch to 1600
-create, on this same DVS, a port group
-in this port group, per host, a vxlan vmkernel interface
Now, in // of that, I understand that basically creating a "logical switch" within NSX creates nothing else than a port group within the distributed switch.
Besides, enabling VXLAN on 1 cluster is apparently not requiring any logical switch conf...Still I was able to read on different places people mixing the logical switches and VXLAN topic which is confusing me.
So : is there any link between VXLAN and NSX logical switches ? At which level ?
You are right enabling VXLAN will do above things(Will adjust MTU only if it is below 1500) and from VCD perspective you have an option to map the right network pool to each org-vdc so that VM's can leverage underlying network virtualization technology. In your case VXLAN network pool. A VXLAN network pool is created when you create a provider virtual datacenter.(PVDC) and you use same network pools accross multiple org-vdc.
Logical Switches/VNI/Virtual Wire/VXLAN switches all are same- from vSphere perspective they are port groups. You can also have external network as VXLAN switches with VCD instead of normal vSphere portgroups.
3) Down to the physical layer : my supposal is that if the vxlan vmkernel is sending/receiving ethernet frames of 1600 bytes, it means that all my physical uplinks also needs to be configured with a MTU of 1600. Do I understand this correctly ?
Yes, MTU from End-End if we are using VXLAN
4) Finally, is it possible to enable VXLAN in DHCP and define, afterwards, a static IP on corresponding vxlan vmkernels ? Because once VXLAN is enabled, I don't see any way to change the ip allocation setting from DHCP to IP Pool.
vCloud Director supports three types of networks.
■ | External networks |
■ | organization vDC networks |
■ | vApp networks |
There are multiple ways through which we can leverage dhcp .From VM perspective you can certainly leverage NSX-EDGE DHCP feature or you can connect the VCD VM- all the way to external network and have a DHCP server there so that i can receive an ip during the bootstrap process. If you go with first option connectivity would be like - VM(VAPP) to NSX-edge(DHCP) connected to External Network OR VM directly connected to external network