Assignment of network addresses and estimations of flow sizes associated with network nodes can be enhanced. Assignment management component (AMC) partitions a set of network addresses into subsets of network addresses associated with respective classes. For respective virtual machines (VMs), an estimator component estimates a flow size associated with a VM based on parameters associated with the VM. AMC classifies VMs based on threshold flow-size values and respective estimated flow sizes of VMs, and assigns VMs to respective sub-groups of VMs associated with respective subsets of network addresses based on respective classifications of VMs. AMC assigns an available network address of a subset of network addresses associated with a class to a VM of a sub-group associated with that class. Estimated flow sizes and performance metrics also are utilized to make determinations regarding VM placement, traffic management, load balancing, resource allocation, and orchestration in cloud networks.