Scale-in and Scale-out of Compute Nodes

Table 1. Scale-in of compute nodes
Scale-in	EFA Impact
Link removal from default physical network	VLAN provisioning for endpoints is done when Neutron ports are unbound to a host or compute. Hence, removing a link which belongs to the default physical network does not have any impact, only the link-mapping table is updated.
Link removal from non-default physical networks	For non-default physical networks, VLAN provisioning is done at the network level. Hence, the links that are removed from non-default networks are automatically removed from the existing networks. On EFA, the interface is removed from the corresponding EPGs. If there are any errors during EFA unbinding, the operation succeeds. This behavior is consistent with the delete port operation.
Links bound to port-channels on non-default physical networks	Removing a link which maps to a LAG interface does not affect EPG unless the last member of the LAG is removed in link mapping. For example, LAGs have two entries in the link mapping. Removing only one entry does not affect the existing EPG. Only when the last entry for that LAG is removed, EFA removes the LAGs from corresponding EPGs.

Table 2. Scale-out of compute nodes
Scale-out	EFA Impact
Link addition to default physical network	VLAN provisioning of endpoints is done when Neutron ports are bound to a host or compute. Hence, adding a link which belongs to the default physical network does not have any impact, only the link-mapping table is updated.
Link addition to non-default physical networks	For non-default physical networks, VLAN provisioning is done during network-create time. Hence, the new links that are added to non-default networks are automatically added to the existing networks. On EFA, the interface is added to the corresponding EPGs. If there are any errors during EFA binding, the whole operation fails.
Links bound to port-channels on non-default physical networks	If the switch link is a LAG interface, as soon as the first link to LAG is added, the corresponding LAG is added to the EPGs. Further link addition on that LAG requires no further changes for EFA.
File option in efa-link-add	File option enables saving link mappings in a file for bulk configuration. If there is an error in adding a link during file replay, the operation is aborted. You can correct the errors and replay it.