Network I/O Control Enhancements

Consolidated I/O or I/O virtualization delivers similar benefits as provided by x86 virtualization in terms of better utilization and consolidation of resources. However, as multiple traffic types flow through a single physical network interface, it becomes important to manage the traffic effectively such that critical application flows don’t suffer because of a burst of low-priority traffic. Network traffic management provides the required control and guarantee to different traffic types in the consolidated I/O environment. In the VMware vSphere 5 platform, NIOC supports traffic management capabilities for the following traffic types or also called as network resource pools:

• Virtual machine traffic

• Management traffic

• iSCSI traffic

• NFS traffic

• Fault-tolerant traffic

• VMware vMotion traffic

• User-defined traffic

• vSphere replication traffic

Similar to CPU and memory resource allocation in the vSphere platform, a network administrator through NIOC can allocate I/O shares and limits to different traffic types, based on their requirements. In this new release of vSphere, NIOC capabilities are enhanced such that administrators can now create user-defined traffic types and allocate shares and limits to them. Also, administrators can provide I/O resources to the vSphere replication process by assigning shares to vSphere replication traffic types. Let’s look at some details on User defined and vSphere replication traffic types.


User-Defined Network Resource Pools

User-defined network resource pools in vSphere 5 provide an ability to add new traffic types beyond the standard system traffic types that are used for I/O scheduling.

Figure below shows an example of a user-defined resource pool with shares, limits and IEEE 802.1p tag parameters described in a table. In this example, Tenant 1 and Tenant 2 are two user-defined resource pools with virtual machines connected to their respective independent port groups. Tenant 1, with three virtual machines, has five I/O shares. Tenant 2, with one virtual machine, has 15 I/O shares. This indicates that during contention scenarios, Tenant 2 virtual machines will have a higher guaranteed share than Tenant 1 virtual machines.



When customers are deploying critical applications on virtual infrastructure, they can utilize this advanced feature to reserve I/O resources for the important, business-critical application traffic and provide SLA guarantees.

Service providers who are deploying public clouds and serving multiple tenants can now define and provision I/O resources per tenant, based on each tenant’s need.


The new resource pools can be defined at the Distributed Switch level by selecting the resource allocation tab and clicking on new network resource pools. After a new network resource pool is defined with shares and limits parameters, that resource pool can be associated with a port group. This association of a network resource pool with a port group enables customers to allocate I/O resources to a group of virtual machines or workloads. The figure below shows the new Tenant 1 and Tenant 2 resource pools created under user-defined network resource pools.


vSphere Replication Traffic

 vSphere replication is a new system traffic type that carries replication traffic from one host to another. NIOC now supports this new traffic type along with other system and user-defined traffic types.


Customers implementing a disaster recovery (DR) solution with VMware vCenter Site Recovery Manager (Site Recovery Manager) and vSphere replication can use this vSphere replication traffic type to provide required network resources to the replication process.


A vSphere replication traffic type can be configured on a Distributed Switch under the resource allocation tab. This traffic type is now part of the system network resource pool. Customers can allocate shares and limits parameters to this traffic type.


IEEE 802.1p Tagging

IEEE 802.1p is a standard for enabling QoS at MAC level. The IEEE 802.1p tag provides a 3-bit field for prioritization, which allows packets to be grouped into seven different traffic classes. The IEEE doesn’t mandate or standardize the use of recommended traffic classes. However, higher-number tags typically indicate critical traffic that has higher priority. The traffic is simply classified at the source and sent to the destination. The layer-2 switch infrastructure between the source and destination handles the traffic classes according to the assigned priority. In the vSphere 5.0 release, network administrators now can tag the packets going out of the host.



Customers who are deploying business-critical applications in a virtualized environment now have the capability to guarantee I/O resources to these workloads on the host. However, it is not sufficient to provide I/O resources just on the host. Customers must think about how to provide end-to-end QoS to the business-critical application traffic. The capability of a Distributed Switch to provide an IEEE 802.1p tag helps such customers meet those requirements for end-to-end QoS or service-level agreements.


IEEE 802.1p tagging can be enabled per traffic type. Customers can select the Distributed Switch and then the resource allocation tab to see the different traffic types, including system and user-defined traffic types. After selecting a traffic type, the user can edit the QoS priority tag field by choosing any number from 1 to 7. Figure below is the screenshot of QoS priority tag configuration for the MyVMTraffic traffic type.


With this post, I have completed the coverage of new networking features in vSphere 5. Also, today VMware has officially announced the genearal availability of vSphere 5.

I will be attending VMworld 2011 during the week of Aug 29th. At VMworld, I have a session on VDS best practices and couple of group discussions. Looking forward to meeting with various partners and customers.

After VMworld, I will focus my attention on writing about the different deployment options with vSphere Distributed Switch (VDS). 


About the Author

Vyenkatesh Deshpande

Vyenkatesh (Venky) Deshpande is a Sr. Technical Marketing Manager at VMware and he is focussed on the Networking aspects in the vSphere platform and vCloud Networking and Security product. Follow Venky on twitter @VMWNetworking