User`s guide

Chapter 6 Virtual Network Interface Cards (vNICs) 111
TCP Segmentation Offload
Virtual NICs support TSO, which allows large chunks of TCP data coming from a
host server to be divided into a smaller TCP segments. When the host server sends
one or more large chunks of data, they travel on the vNIC. On the 10 GE or 10-Port
GE module where the vNIC is terminated, the large chunks of data are divided into
smaller ones with a size determined by the maximum segmentation size (MSS).
Then, these smaller MSS-size packets are sent onto the network. TCP segmentation
offload (TSO) increases the outbound throughput and relieves CPU utilization on
the host by performing TCP-packet processing functions on the I/O module instead
of on the host.
Note – Another feature called Receive Batching performs the opposite function
(coalescing numerous smaller packets) for traffic that the host server receives. Both
TSO and Receive Batching can be configured on the same vNIC if your host(s) need
performance optimization for both directions of traffic. For information, see “Receive
Batching” on page 114.
Requirements
TSO support has the following requirements:
■ For HA vNICs, both the primary and secondary vNIC must have the same TSO
configuration.
■ The following table shows the minimum versions that support TSO.
■ This feature is supported only on Oracle Fabric Interconnect Gigabit Ethernet I/O
cards that are listed as card type EthIB when you list the modules. All new
Gigabit Ethernet I/O cards shipped from the factory will be EthIB, but some
existing customers might have older cards that are not EthIB, and therefore will
OS/Hypervisor Type Version
XgOS XgOS version 3.6.0 and later
Red Hat Linux 5 GA and later Host driver version 5.x and later
ESXi 5.0 and later Host driver version 5.3.0 and later
Windows None currently, but TSO on Windows hosts will be
supported in a future release of host drivers.