diff --git a/vmware_nsxlib/v3/nsx_constants.py b/vmware_nsxlib/v3/nsx_constants.py
index 43c5e8f2..dd309525 100644
--- a/vmware_nsxlib/v3/nsx_constants.py
+++ b/vmware_nsxlib/v3/nsx_constants.py
@@ -28,6 +28,9 @@ ATTACHMENT_MDPROXY = "METADATA_PROXY"
 
 VIF_RESOURCE_TYPE = "VifAttachmentContext"
 
+VIF_TYPE_PARENT = "PARENT"
+VIF_TYPE_CHILD = "CHILD"
+
 ALLOCATE_ADDRESS_NONE = "None"
 
 # NSXv3 L2 Gateway constants