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The Benefits of Network Virtualization Offload Technologies to Optimize Performance for NVGRE

Posted June 3rd, 2013 by Brandon Hoff

As we have discussed before, NVGRE or Network Virtualization using GRE (an informative RFC) defines how to build virtual networks in Hyper-V environments.  Virtual Network Fabrics (VNF) creates a virtual network infrastructure where a virtual machine (VM) can be created and moved without any limitations that would be imposed by the legacy network infrastructure.

With NVGRE, VMs live on a single virtual network defined by a Tenant Network ID (TNI) in the NVGRE virtual network.  VMs can be moved from any physical server to any physical server and NVGRE creates a virtual L2 network across physical L3 boundaries so that the VM is able to keep its MAC and IP address no matter where it moves.  Furthermore, network configuration becomes automated so that any network changes required to create a new VM can be done in minutes instead of days.  This improves the agility of private and hybrid cloud infrastructures and lowers the costs of network management for private and hybrid cloud environments.

It is important to note that NVGRE can be implemented in software and the solution works well on Converged Network Adapters (CNAs) and Network Interface Cards (NICs) provided by Emulex.  That said, as Microsoft stated in their presentations at the 2011 Windows Build Conference (here and here and slides here) NIC participation in NVGRE, specifically offloads, to build encapsulated packets for NVGRE, is essential.  Today, without NIC participation, GRE breaks today’s task offloads, which disables nearly 10 years of NIC enhancements that improves performance for high performance Ethernet networks.  Specifically, NVGRE breaks LSO and other NIC performance optimizations.  This creates a performance penalty, as illustrated in the table below.

Note:  These test results are illustrative in nature and will vary based on VM density, server configuration, and other test parameters.

Basically, network throughput is reduced by 27% in this test scenario.  This means that VM density may be reduced by 27% which is significant.  Therefore, Emulex and Microsoft have been working together to solve this performance issue.  The solution is to add additional NIC offloads to improve system performance.  Today, Emulex announced our forthcoming Virtual Network Exceleration™ (VNeX)  virtual network offload technology that solves these problems and provides optimal performance for virtual networks.  Emulex virtual network offload technology provides the following:

  1. Send
    1. Checksum computation for IPv4/IPv6 and TCP payload (inner and outer)
    2. LSO V1 and V2
    3. Receive
      1. RSS/VMQ
      2. Checksum validation for IPv4/IPv6 and TCP payload (inner and outer)
      3. And specific Emulex virtual network offload technology integration for NVGRE

An illustration of Emulex’s virtual network offload technology is shown below:

The graph below shows the performance improvement with offloads optimized for NVGRE.

Note:  These test results are illustrative in nature and will vary based on VM density, server configuration, and other test parameters.

Bottom line:  NIC offload for NVGRE significantly improves performance.  NVGRE is a great solution to build virtual network fabrics and Emulex’s virtual network offload technology delivers the following benefits:

  1. Improved VM density for Hyper-V Environments
  2. Better network throughput
  3. Lower CPU utilization when implementing NVGRE

Emulex leads in technologies for virtual network fabrics, and we look forward to providing more proof points to illustrate the benefits of virtual network offload technologies.

Some of these products may not be available in the U.S.  Please contact your supplier for more information.

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