What’s New in VMware vSphere™ 5.0 Networking


With the release of VMware vSphere™ 5.0 (“vSphere”), VMware brings a number of powerful new features and enhancements to the networking capabilities of the vSphere platform. These new network capabilities enable customers to run business-critical applications with confidence and provide the flexibility to enable customers to respond to business needs more rapidly. All the networking capabilities discussed in this document are available only with the VMware vSphere Distributed Switch (Distributed Switch).

There are two broad types of networking capabilities that are new or enhanced in the VMware vSphere 5.0
release. The first type improves the network administrator’s ability to monitor and troubleshoot virtual
infrastructure traffic by introducing features such as:

  • NetFlow
  • Port mirror

The second type focuses on enhancements to the network I/O control (NIOC) capability first released in
vSphere 4.1. These NIOC enhancements target the management of I/O resources in consolidated I/O
environments with 10GB network interface cards. The enhancements to NIOC enable customers to provide
end-to-end quality of service (QoS) through allocating I/O shares for user-defined traffic types as well as tagging packets for prioritization by external network infrastructure. The following are the key NIOC

  • User-defned resource pool
  • vSphere replication trafc type
  • IEEE 802.1p tagging

The following sections will provide higher-level details on new and enhanced networking capabilities in vSphere 5.0.

Network Monitoring and Troubleshooting

In a vSphere 5.0 environment, virtual network switches provide connectivity for virtual machines running on VMware® ESXi™ hosts to communicate with each other as well as connectivity to the external physical
infrastructure. Network administrators want more visibility into this traffic that is flowing in the virtual infrastructure. This visibility will help them monitor and troubleshoot network issues. VMware vSphere 5.0 introduces two new features in the Distributed Switch that provide the required monitoring and troubleshooting capability to the virtual infrastructure.


NetFlow is a networking protocol that collects IP traffic information as records and sends them to a collector such as CA NetQoS for traffic flow analysis. VMware vSphere 5.0 supports NetFlow v5, which is the most common version supported by network devices. NetFlow capability in the vSphere 5.0 platform provides visibility into virtual infrastructure traffic that includes:

  • Intrahost virtual machine traffic (virtual machine–to–virtual machine traffic on the same host)
  • Interhost virtual machine traffic (virtual machine–to–virtual machine traffic on different hosts)
  • Virtual machine–physical infrastructure traffic

Figure 1 shows a Distributed Switch configured to send NetFlow records to a collector that is connected to an external network switch. The blue dotted line with arrow indicates the NetFlow session that is established to send flow records for the collector to analyze.

NetFlow Traffic

Figure 1. NetFlow Traffic


NetFlow capability on a Distributed Switch along with a NetFlow collector tool helps monitor application flows and measures flow performance over time. It also helps in capacity planning and ensuring that I/O resources are utilized properly by different applications, based on their needs.

IT administrators who want to monitor the performance of application flows running in the virtualized
environment can enable flow monitoring on a Distributed Switch.


NetFlow on Distributed Switches can be enabled at the port group level, at an individual port level or at the uplink level. When configuring NetFlow at the port level, administrators should select the NetFlow override tab, which will make sure that flows are monitored even if the port group–level NetFlow is disabled.

Port Mirror

Port mirroring is the capability on a network switch to send a copy of network packets seen on a switch port to a network monitoring device connected to another switch port. Port mirroring is also referred to as Switch Port Analyzer (SPAN) on Cisco switches. In VMware vSphere 5.0, a Distributed Switch provides a similar port mirroring capability to that available on a physical network switch. After a port mirror session is configured with a destination—a virtual machine, a vmknic or an uplink port—the Distributed Switch copies packets to the destination. Port mirroring provides visibility into:

  • Intrahost virtual machine traffic (virtual machine–to–virtual machine traffic on the same host)
  • Interhost virtual machine traffic (virtual machine–to–virtual machine traffic on different hosts)

Figure 2 shows different types of traffic flows that can be monitored when a virtual machine on a host acts as a destination or monitoring device. All traffic shown by the orange dotted line with arrow is mirrored traffic that is sent to the destination virtual machine.

NetFlow Traffic

Figure 2. Port Mirror Traffic Flows When Destination Where Packets Are Mirrored Is a Virtual Machine


The port mirroring capability on a Distributed Switch is a valuable tool that helps network administrators in debugging network issues in a virtual infrastructure. The granular control over monitoring ingress, egress or all trafc of a port helps administrators fne-tune what trafc is sent for analysis.


Port mirror configuration can be done at the Distributed Switch level, where a network administrator can create a port mirror session by identifying the traffic source that needs monitoring and the traffic destination where the traffic will be mirrored. The traffic source can be any port with ingress, egress or all traffic selected. The traffic destination can be any virtual machine, vmknic or uplink port.


Download a full What’s New in VMware vSphere™ 5.0 Networking Technical White Paper.

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