Creating and Administering an EVS Controller

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An EVS controller provides functionality for the configuration and administration of an elastic virtual switch and all the resources associated with it. You must set properties for an EVS controller, which captures information necessary for implementing Layer 2 segments across physical machines. For more information, see EVS Controller.

Planning for an EVS controller includes the following considerations:

Determine whether you are implementing the elastic virtual switch by using a VLAN, VXLAN, or both.
- If you use a VLAN to implement the elastic virtual switch, you need to set the properties uplink-port and vlan-range.
  
  Note - If you use a VLAN to implement the elastic virtual switch on multiple nodes, you need to enable VLAN trunking on the appropriate physical switch ports. For more information, refer to the switch manufacturer's documentation.
- If you use a VXLAN to implement the elastic virtual switch, you need to set the properties vxlan-range and uplink-port or vxlan-addr. Optionally, you can also set the properties vxlan-mgroup and vxlan-ipvers.
  
  Note - If you use a VXLAN to implement the elastic virtual switch, you cannot set the value of the vxlan-addr property to the IP address of an IPMP interface, while creating the VXLAN. The IPMP interfaces are not supported by VXLANs.
If the compute nodes do not have the same datalink, then for every compute node, you need to specify the datalink for the uplink-port property.

For example, consider two compute nodes, host1 with the datalink net2 and host2 with the datalink net3. You need to specify the datalinks of both the hosts when you set the uplink-port property as follows:
```
# evsadm set-controlprop -h host1 -p uplink-port=net2
# evsadm set-controlprop -h host2 -p uplink-port=net3
```
Note - After you create an elastic virtual switch, you cannot modify the EVS controller properties for that elastic virtual switch. Any modifications to the EVS controller properties are reflected in the new elastic virtual switches that you create.