Architecting for Performance: Network - Virtualizing SQL Server with VMware - page 250

that you are on at least Update 2 if you are using vSphere 5.0. See VMware KB
2006277 for further information.
When compared to Figure 8.1 , the E1000E adapter shows an improvement in
performance of greater than 1Gbps when using jumbo frames, and VMXNET3 shows an
improvement of slightly more than 0.5Gbps. A much greater improvement in network
performance is demonstrated when two VMs are on the same host, as shown in Figure
8.5 .
Figure 8.5 Same host virtual network adapter performance with jumbo frames.
Although throughput is higher in Figure 8.5 , so is CPU utilization. This is due to the
hypervisor not being able to make use of the physical network adapter offload
capabilities when transmitting between the two VMs on the same host. However, the
CPU cost is lower per Gbps of throughput compared to the test between hosts in Figure
8.4 .
In order for you to use jumbo frames, it must be configured consistently from the source
to the destination system. This means you need to configure support for jumbo frames in
Windows for the virtual network adapter, on the virtual switch within VMware vCenter
or ESXi, and on the physical network. Jumbo frames configuration needs to be enabled
on any network devices between the source and destination systems that will carry the
packets. As a result, it can be much easier to configure jumbo frames when
implementing new network equipment, although with proper planning and verification, it